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My articles: Is the edifice of radiation protection built on a lie?

2012-01-27T20:17:00.000+05:30

My articles: Is the edifice of radiation protection built on a lie?

Is the edifice of radiation protection built on a lie?

2012-01-27T20:15:00.000+05:30

S & T

Published: January 26, 2012 01:39 IST | Updated: January 26, 2012 01:39 IST

Is the edifice of radiation protection built on a lie?

The Linear No Threshold concept assumes that the risk from radiation exposure varies linearly with total dose with no threshold

Recently, Edward Calabrese, an environmental toxicologist at the University of Amherst found out that Dr Hermann J. Muller, famous radiation geneticist knowingly lied in his Nobel Prize lecture when he claimed that there was “no escape from the conclusion that there is no threshold.” Calabrese described his discovery in September in Archives of Toxicology and Environmental and Molecular Mutagenesis

In 1927, Muller discovered that x-ray irradiation produces mutations in male fruit-fly germ cells. For this, he received the Nobel Prize in Physiology or Medicine in 1946. Many believe that Muller's assertion became a corner stone of radiation protection. This is the Linear No Threshold (LNT) concept which assumes that the risk from radiation exposure varies linearly with total dose with no threshold and any dose however small has an adverse effect.

Expert bodies accepted this model because of its simplicity in the management of radiation protection programmes.

“However, it has done much damage to speak of ‘no safe level of radiation' in scaring not only the public, but also those professionally involved in peacetime health physics who have not been involved in high levels and emergency situations,” Allen Brodsky, Adjunct Professor of Radiation Science, Georgetown University responded to an e-mail query.

In response to an e-mail query Calabrese disclosed that a reviewer of his article on the history of dose-response argued that he had not done a good job on the Muller section and key early radiation mutation studies. Calabrese found that a paper from the University of Rochester by Curt Stern and Casper on fruit-fly irradiation and germ cell mutation was published in 1948 but it was actually completed in August of 1946.

“This study was very important because it did not support a linear dose response and because it was the strongest study to date...using the lowest dose rate etc. I knew that Muller gave his Nobel Prize lecture on Dec. 12, 1946. So the question was whether Muller was aware of the new findings before his major speech,” Calabrese replied

By reviewing Stern's correspondence with Muller, Calabrese established that Muller knew of the findings which contradicted his theory a month prior to the Nobel Lecture.

Calabrese asserts that Muller's passionate beliefs influenced the way government and society viewed the risks of low doses of radiation. The 1956 recommendations of the US National Academy of Sciences (NAS) BEAR (Biological Effects of Atomic Radiation) I Committee reflected these views. Regulating ionizing radiation as if there was no safe dose began!

James Schwartz, a biographer of Muller, Kenneth Muller, Hermann Muller's grandson and Elof Axel Carlson, Muller's former student do not agree with Calabrese. Some feel that Calabrese, a supporter of radiation hormesis (beneficial effect) has conflict of interest. The balance of evidence shows that the edifice of radiation protection is not built on a lie.

Dr Evan B. Douple, Associate Chief of Research at the Radiation Effects Research Foundation, Hiroshima, does not think that the LNT hypothesis would have lost its applicability if Professor Muller would not have made the passionate statement in his speech.

“……. by the time the BEIR (Biological Effects of Ionizing Radiation) committees of the National Academy of Sciences began updating the risk estimates, the mutation risk was superseded by the risk of cancer. Having been intimately involved with the BEIR VI and BEIR VII studies, I can assure you that the voluminous data reviewed by the committee members that related to supporting or refuting LNT, was not swayed or overly influenced by the shape of a dose-response curve in the mutation work of Muller,” Douple responded. (Dr Douple was Director, Board on Radiation Effects Research, National Research Council)

He is not even sure that Calabrese's interpretation and assessment that Muller was deceptive in his presentation is necessarily accurate or fair.

“Although somatic mutations became a dogma for radiation carcinogenesis, the LNT for carcinogenesis was based on (a) analyses of cancer induction in rodent models, (b) biophysical characteristics of energy deposition, ionizations, and DNA damage in cells, and (c) the early epidemiological studies of cancer in the Japan A-bomb survivors,” he clarified in an e-mail.

He does not think that the conjecture and personal interpretation of an untestable accusation will have significant impact among the radiation protection community.

Prof Ludwig E. Feinendegen, Heinrich-Heine University, Germany thought that “the new revelations on low-dose effects in the realm of biological responses are making an impact on the radiation protection community — as it appears currently from the defensive manner of their arguments for keeping the LNT model, at least for the time being. Calabrese has done us a great favour by his new paper on Mueller's mistake.”

That there is no safe level of radiation continues to be a useful assumption in radiation protection. It is yet to be proved as a scientific fact.

Douple believes that the exhaustive efforts of those who claim that demonstrating hormesis (beneficial effect) or the presence of thresholds will revolutionize the radiation protection field are misguided.

“We need to educate the public regarding the importance of ‘acceptable levels of risk'—levels that are believed to include risks, but risks for adverse effects that are so small that one would not be able to observe and measure an excess of the effects with a realistic study. Only then will the fear and paranoia associated with radiation effects gradually become less and less and sources for energy production can be fairly and objectively be evaluated,” Douple proposed as a realistic way forward.

Regulators want dose limits for enforcing radiation protection. What is the threshold dose value they will accept for enforcement? Calabrese and his followers have not yet responded to my query.

The French Academy of Sciences, the only scholarly body which has views closer to those of Calabrese on hormesis conceded that on the basis of present knowledge, it is not possible to define the threshold level (between 5 and 50 mSv) or to provide the evidence for it. The dose limit for workers recommended by the International Commission on Radiological Protection (ICRP) is 20 mSv per year averaged over five years with no year exceeding 50 mSv. The dose levels to radiation workers achievable are so low that the risk from them is negligible. Negligible risk is no risk at all. That we cannot rule out beneficial effects of radiation is also a comforting thought.

K.S. Parthasarathy

Raja Ramanna Fellow, Department of Atomic Energy (ksparth@yahoo.co.uk)

Keywords: radiation exposure

www.indoeuropean.in

Printable version | Jan 26, 2012 8:32:36 AM | http://www.thehindu.com/sci-tech/article2831847.ece

Anti nuclear activists are lying or are ignorant

2011-12-17T12:43:00.000+05:30

With malice towards none, and knowledge for all!

Those keen to sift facts from fiction may read the following note:

There is widespread wrong information about the status of nuclear power in USA after 1979, the year in which the accident occurred at the Three Mile Island nuclear power station.

Many anti nuclear activists state that since 1977, USA has not built any new nuclear power plant. There is a little confusion here. It is true that USA has not issued any new licence to construct a nuclear power plant. Government approved up-rating the power of existing reactors by 6000MW from 1977 to 2011. From 2011 to 2015, 3211 MWe will be added.

Electric companies connected 50 out of the 104 currently operating nuclear power plants in USA to the grid after 1979, the year in which the Three Mile Island accident occurred. Nineteen of them after 1986, the year in which the Chernobyl accident occurred. Fifty three out of the 59 French reactors came on line after 1979.

The net capacity factor of a power plant is the ratio of the actual output of a power plant over a period of time and its potential output if it had operated at full capacity the entire time.

The capacity factor of nuclear power reactors in USA averaged about 57 % in 1980. It increased gradually. From 2004 till 2010 (the latest data)it averaged over 90%. Twenty two US nuclear power reactors out of the 104 exceeded a capacity factor of 100%. In 2010 the capacity factors of other modes of power generation in % were: Biomass 85.5;.Geothermal 71.6;Coal (Steam turbine) 65.4;Gas(Combined cycle) 45.8;Hydro 29.4; Wind 29.1;Solar 17.7;Gas (Steam turbine) 12.9; oil (steam turbine) 8.9

Anti-nuclear critics claim that Russia stopped constructing nuclear power after 1986, the year in which the accident occurred at the Chernobyl nuclear power station.

What is the factual position?

Russian power utilities started commercial operation of eight nuclear power reactors after 1986 . One of them in May 1986 a month after the Chernobyl accident. The last one of 950 Mgawatt became critical on November 11, 2011 and is operating at 50% power as one December 13, 2011.

Russia currently has an installed nuclear power capacity of 24,164 MWe from 33 reactors. It has started construction and planned and proposed to erect 53 nuclear power reactors with a total capacity of over 50,000 MWe

China operates 15 reactors with a total capacity of 11,881 MWe starting from 1994. Nuclear power reactors under construction and planned number 77 with a total capacity of 85,750MW.

Additional reactors are planned, including some of the world's most advanced, to give a five- or six-fold increase in nuclear capacity to at least 60 GWe by 2020, then 200 GWe by 2030, and 400 GWe by 2050.

Until March 2011, Germany generated 25% of its electricity from nuclear energy using 17 reactors.In 1998, Germany decided to phase out nuclear power; in 2009 Government cancelled this policy but shut down eight reactors post Fukushima even before the factual position about the accident was known.

French and Czechs are happy going to their banks. To compensate for the power generated by the seven reactors, Germany imports power from France and Czech Republic. France’s share of export to Germany increased by 50% in the first half of the year; Czech’s share went up by a whopping 673%(The Sydney Herald, November 26, 2011)

According to the paper, at peak times, up to four nuclear power stations in France and the Czech Republic are running just to cater to the demands of Germany

Kudankulam Reactors: Nuclear myths

2011-11-24T22:12:00.000+05:30

PTI FEATURE

VOL NO XXVII(46)- 2011 November 12, 2011

SCIENCE & TECHNOLOGY

PF-183/2011

Kudankulam Reactors: Nuclear Myths

By Dr K S Parthaarathy

Recently, an energy specialist showed that under realistic assumptions, India will not be able to maintain a modest annual per capita power need of about 2000 kWh by 2070 by renewable energy alone; the maximum potential for renewable will be 36.1%. (Current Science, Sept 10, 2011), Fossil fuel and nuclear will continue to play their role. He believes that hundred years later, India has to depend on nuclear power only.

Recently anti nuclear activists scored over staunch nuclear power proponents by planning a fast of infants against Kudankulam project! Infants cannot protest; parents forced them to fast. Mercifully it was only for one hour. I do not know whether it is legal or whether it may be considered as child abuse. It was a clever ploy to get publicity. Next, the activists may argue that reactors will kill babies and babies’ babies!

Misinformation, misconcepts and other issues are coming in the way of commissioning the first Generation 3+ advanced nuclear power reactor in India.

In an article titled “India: People power vs. nuclear power (The Daily Star, October 17, 2011), Praful Bidwai claimed that Kudankulam reactors will daily draw in millions of litre of freshwater, and release it at a high temperature into the sea, affecting the fish catch on which lakhs of livelihoods depend.

The reactors will not use fresh water but water from a desalination plant erected at site. The temperature of water from the reactors discharged in to the sea will be in compliance with the stipulations of the Ministry of Environment and Forests (MOEF), Government of India. This discharge will not affect fish catch nor will it adversely affect marine ecology.

Bidwai’s observation that the reactors are being built within a one-kilometre radius of major population-centres, violating the 1.6-km "nil-population" zone stipulation is not true.

Nuclear Power Corporation India Limited (NPCIL) keeps an area of 1.5 kilo-metre radius

around the reactors under its exclusive control as required by the Atomic Energy Regulatory Board (AERB) Code on Safety in Nuclear Power Plant Siting. The site satisfies other AERB stipulations.AERB allows the reactors to release effluents and emissions routinely. NPCIL ensures that the limits for releases prescribed by the Atomic Energy Regulatory Board (AERB) are not exceeded.

Bidwai scares people by describing radioactivity as “a regular poison you can’t see, touch or smell”. He knows that these shortcomings have not come in the way of using radiation in medical, industrial and research applications. That we can measure radioactivity and radiation accurately at extremely low levels helps to enforce regulatory limits on releases and emissions.

Bidwai notes that scientific studies covering 136 nuclear sites in seven countries showed some adverse health effects. The reference is to a paper by Baker and Hoel in the European Journal of Cancer Care (2007). It offered some evidence of elevated leukemia rates among children living near nuclear facilities. The authors described the limitations of the study and also referred to studies which did not show any effect. They referred to studies in which leukemia effect was seen before the nuclear facilities started operation!

Specialists criticized the study for its methodological weaknesses, such as combining heterogeneous data (different age groups, sites that were not nuclear power plants, different zone definitions), arbitrary selection of 17 out of 37 individual studies, exclusion of sites with zero observed cases or deaths, etc (Wikipedia).

Though the paper deals with leukemia only and no other effects, Bidwai claimed that the study shows “abnormally high leukemia rates among children and higher incidence of cancers, congenital deformities, and immunity and organ damage”. Nuclear critics have a way of shaming epidemiologists and other specialists by cherry picking data and inventing conclusions!

The Chernobyl accident caused two deaths immediately and 28 deaths within a few months. According to the United Nations Scientific Committee on the Effects of Atomic Radiation (2011), there were 15 more deaths due to thyroid cancers. Opinions on number of potential deaths differ.

Bidwai claimed (34,000 to 95,000) deaths, lot less than one million predicted by a Greenpeace supported report. He claimed that the numbers of deaths are still “climbing”. Such myths cloud the reality that no such dramatic increases have been identified. Actually radiation scaremongers caused 100,000 to 200,000 abortions in Europe!

A nuclear reactor will not explode like a nuclear bomb as its fuel contains only less than 5% enriched uranium. This is a basic lesson in reactor physics. Bidwai’s argument that a reactor is a barely controlled nuclear bomb has no scientific basis.

Bidwai recommends that “there are perfectly sound, safe, cost-competitive renewable energy alternatives to nuclear power”. We do not now have the luxury to choose any mode of power generation. The Government’s programme to erect solar generating capacity of 20,000 MWe by 2020, equal to that of the then nuclear capacity may be seen in that context.. On a percentage basis, India now produces more renewable energy than Germany.

Ranked fifth in the world, India’s installed wind-power capacity is 14,158 MW, three times our nuclear power capacity.

A Mumbai daily quoted Dr M P Parameswaran, a DAE veteran (whatever that may mean) as saying that “No N-plant in India safe”-an opinion, not based on facts.

“We are yet to master the technology to decommission a reactor. That is why we keep on extending the life period of some of the reactors which have outlived their utilities”, he added another skewed opinion.

Like other anti nuclear activists, he believes that since 1977, USA has not built any new nuclear power plant. There is a little confusion here. It is true that USA has not issued any new licence to construct a nuclear power plant.

He says that in 1974, all US Nobel Prize winners were opposed to nuclear power plants. It is very unlikely. In spite of the “opposition”, nuclear electricity has increased over seven fold during 1974 to 2010.

The one Nobel Laureate, Roald Hoffmann, I interviewed a few years ago, supports nuclear power; he wanted nuclear proponents to highlight its environmental advantages. Currently, Steven Chu, a Nobel Laureate is the US Energy Secretary ; he consistently votes for nuclear power

Dr Parameswaran asks why the Indian nuclear establishment is silent about the pollution caused to the marine wealth of the country by the coolant water discharged to the sea-another misconception!

A thermo-ecology study carried out at Kalpakkam and Kaiga stations with several experts from institutions such as the National Institute of Oceanography (NIO), Central Electro Chemical Research Institute (CECRI) and several universities in the country did not reveal any adverse impact on marine ecology near nuclear power plant sites.

With the erection, commissioning and operation of the reactors at Kudankulam, Indian scientists and engineers will demonstrate how they can effortlessly absorb and master Generation 3+ nuclear power technology. This will enable the country to face the challenges in electrical capacity addition with renewed vigour and confidence.

-PTI Feature

How safe Kudankulam nuclear power reactors are

2011-11-13T14:33:00.000+05:30

How safe Kudankulam nuclear power reactors are

K S Parthasarathy

The Hindu SAFETY PRECAUTION: The reactor has double containment and the annulus between the two is kept at negative pressure to prevent any radioactivity if released, from escaping. Photo: A. Shaikmohideen

Twenty-five 1,000 MW VVER reactors are in operation in five countries. Kudankulam plants have more advanced safety features

The Unit 1 of the Kudankulam Nuclear Power Project (KKNPP) is under advanced stage of commissioning. Construction of Unit 2 is progressing well. In the meanwhile, sections of the public have expressed apprehensions about the safety of these reactors. Lack of understanding, misconceptions and misinformation contribute to this. Apparently, the Fukushima accident and other issues influence them.

Twenty-five VVER 1,000 MW reactors are in operation now in five countries. Nine more are under construction. The version offered to India is more recent and has more advanced safety features.

Satisfactory

Atomic Energy Regulatory Board (AERB) satisfied itself that the plant is of proven design. Indianspecialists visited Russia and had significant exchange of information from nuclear power plant designers. Indian engineers had completed licensing training process in either Balakova nuclear power plant (NPP) or Kalinin NPP.

The AERB and Bhabha Atomic Research Centre (BARC) and specialists from reputed academic institutions such as the Indian Institute of Technology, Mumbai, the Boilers Board and the Central Electricity Authority have spent over 7,000 man-days in carrying out the safety review and inspection of the Kudankulam reactors.

These system-wise reviews were comprehensive. AERB used relevant documents from the International Atomic Energy Agency (IAEA) and IAEA's peer reviews of VVER for safety assessment of these reactors.

These reactors belong to the Generation 3 + category (with more safety features than Generation 3) with a simpler and standardised design.

The Kudankulam site is located in the lowest seismic hazard zone in the country. The water level experienced at the site due to the December 26, 2004 tsunami, triggered by a 9.2 earthquake was 2.2 metres above the mean sea level. The safety-related buildings are located at higher elevation (SafetyDiesel Generators,9.3 metre) and belong to the highest seismic category and are closed with double sealed, water leak tight doors.

The reactors have redundant, diverse and thus reliable provisions needed to control nuclear reactions, to cool the fuel and to contain radioactive releases. They have in–built safety features to handle Station Black Out.

Besides fast acting control rods, the reactors also have a “quick boron injection system”, serving as a back-up to inject concentrated boric acid into the reactor coolant circuit in an emergency. Boron is an excellent neutron absorber.

Retains radioactivity

The enriched uranium fuel is contained in Zirconium-Niobium tubes. It can retain the radioactivity generated during the operation of the reactor. The fuel tubes are located in the 22 cm thick Reactor Pressure Vessel (RPV) which weighs 350 tonnes. RPV is kept inside a one metre thick concrete vault.

The reactor has double containment, inner 1.2 metre-thick concrete wall lined on the inside with a 6 mm layer of steel and an outer 60 cm thick concrete wall. The annulus between the walls is kept at negative pressure so that if any radioactivity is released it cannot go out. Air carrying such activity will have to pass through filters before getting released through the stack. Multiple barriers and systems ensure that radioactivity is not released into the environment.

KKNPP-1&2 has many new safety systems in comparison with earlier models. The Four-train Safety-System instead of just one system leads to enhanced reliability. The reactors have many passive safety systems which depend on never-failing forces such as gravitation, conduction, convection etc.

Decay heat removal

Its Passive Heat Removal System (PHRS) is capable of removing decay heat of reactor core to the outside atmosphere, during Station Black Out (SBO) condition lasting up to 24 hours. It can maintain hot shutdown condition of the reactor, thus, delaying the need for boron injection.

It works without any external or diesel power or manual intervention.

The reactors are equipped with passive hydrogen recombiners to avoid formation of explosive mixtures .The reactors have a reliable Emergency Core Cooling System (ECCS).

Core catcher

Located outside the reactor vessel, a core catcher in the form of a vessel weighing 101 tonnes and filled with specially developed compound (oxides of Fe, Al & Gd) is provided to retain solid and liquid fragments of the damaged core, parts of the reactor pressure vessel and reactor internals under severe accident conditions.

The presence of gadolinium (Gd) which is a strong neutron absorber ensures that the molten mass does not go critical. The vessel prevents the molten material from spreading beyond the limits of containment. The filler compound has been developed to have minimum gas release during dispersal and retention of core melt.Rat

Fukushima plant spread gloom; the Onagawa plant close to it, in contrast, shut down safely; its gym served for three months as a shelter for those made homeless (Reuters, Oct 21). The plant showed that it is possible for nuclear facilities to withstand even the greatest shocks and to retain public trust.

Kudankulam reactors are more modern and safe. Exercising due diligence, AERB issued clearances to it at various stages. Public may rest assured thatIndian scientists and engineers will operate the reactor safely.AERB shall continue to enforce measures to maintain safe operation of these advanced nuclear power reactors.

The author is Raja Ramanna Fellow, Department of Atomic Energy and can be reached at ksparth@yahoo.co.uk

Keywords: Kudankulam nuclear plant, KNPP, nuclear safety, nuclear power

Is radiation a must for cells' normal growth?

2011-07-07T16:55:00.000+05:30

Published: July 7, 2011 01:55 IST | Updated: July 7, 2011 02:05 IST

Is radiation a must for cells' normal growth?

K.S. PARTHASARATHY

AP Scientists monitored the bacterial growth by assaying for protein, optical density of the cultures and cell agar plate counts. File photo

Both studies demonstrated a stress response when cells were grown under reduced radiation conditions

The March, 2011 issue of Health Physics published an interesting paper titled “Exploring Biological Effects of Low Level Radiation from the other Side of Background” summarizing the results from a Low Background Radiation Experiment carried out in Waste Isolation Pilot Plant (WIPP), an underground lab at New Mexico and those from a sister experiment conducted at the Lovelace Respiratory Research Institute, Albuquerque.

The recommendation

This was part of a $150 million, five-year long, low-dose research project recommended by 26 scientists highly regarded in radiobiology research community and representing competing radiation effects hypotheses.

WIPP is located at a depth of 650 metre in the middle of a 610 metre thick ancient salt deposit that has been stable for more than 200 million years. The radioactivity content of the salt deposit is extremely low.

The radiation levels in the lab are ten times lower than the normal natural background radiation levels. The contribution to the background from potassium-40, the only identifiable radionuclide present in the lab can also be reduced further by using a modest amount of shielding. Massive, 650 metre thick, salt reduced the cosmic ray background.

Highly resistant

Researchers incubated Deinococcus Radiodurans, a bacterium which is highly resistant to radiation, above-ground and in WIPP in a 15 cm thick pre-world war II steel chamber; that steel is not contaminated by traces of radio-nuclides from nuclear weapons fallout.

The surface radiation levels averaged 3.1 micro Roentgen per hour; the level underground was 0.6 microroentgen per hour and in the preWW II chamber it was as low as 0.2 microroentgen per hour. [Roentgen is a unit of radiation exposure. It depends on the ability of radiation to ionize air. Radiation exposure is one roentgen when the ionizing radiation releases one esu (electrostatic unit of charge) of charge in a cc of air at Normal temperature and Pressure (NTP)]

Scientists monitored the bacterial growth by assaying for protein, optical density of the cultures and cell agar plate counts. Though data had relatively high variability, the three indicators of cell growth demonstrated that the cells grown underground were inhibited and grew increasingly so with increasing time underground (Health Physics, 2011).

In the second experiment, researchers exposed a type of human lung cells at 1.75 mGy per year; another sample of cells to 0.3 mGy per year by using a 10 cm lead shield. The former corresponds to a typical background radiation level. Gy is a unit of absorbed dose, when the radiation energy absorbed in material is one joule per kg.

Since Gy is a very large unit, submultiples such as mGy — milli Gy (one thousandths of Gy) are used.

They controlled the temperature, carbon dioxide and humidity levels in the two incubators in which the cells were placed ensuring that these parameters were statistically the same.

Standard methods

They analyzed the exposed cells directly by standard methods for the presence of heat shock proteins or by exposing the cells to a single x-ray dose of 10 cGy and then assayed for heat shock proteins.(cGy or centiGy is one hundredth of a Gy)

The researchers found that shielding cells from natural radiation upregulated ( initiated the process of increasing the response to a stimulus) the expression of two out of three stress proteins and follow on x-ray exposure further upregulated expression.

They obtained similar results with the bronchial epithelial cells. Both studies demonstrated a stress response when cells were grown under reduced radiation conditions. Does it show that radiation is necessary for normal growth of cells?

A few years ago, mainstream scientists should have shown a smirk on their face followed by a grin if they heard this conclusion. Not any more. Many outstanding specialists feel that at the end of five years, they may be able to develop a model based on exposing organisms to near zero levels of radiation, a model based on sound science.

Profound impact

It may lead to increasing the levels of radiation considered safe; it will have a profound impact on the economics of decommissioning nuclear facilities, long term storage of radioactive waste, construction of nuclear power facilities among others. This requires drastic changes in public perception.

Raja Ramanna Fellow, Department of Atomic Energy

ksparth@yahoo.co.uk

Keywords: radiation effects , K S Parthasarathy

Radiation dose limit for eye lens slashed

2011-06-03T16:31:00.000+05:30

Radiation dose limit for eye lens slashed

K.S. Parthasarathy

The Hindu A Phakonit Cataract operation in progress at a hospital in Guntur. File photo

The lens of the eye is one of the most radiation sensitive tissues in the body. If the eye lens which is normally crystal clear receives a high enough radiation dose it may become partly cloudy or totally opaque depending on the dose. Radiation protection agencies have prescribed dose limits to the lens to prevent induction of lens opacity or cataract.

On April 21, this year, the International Commission on Radiological Protection (ICRP) which issues recommendations on radiation protection, slashed the dose limit for the lens of the eye to 20mSv in a year, averaged over defined period of five years, with no single year exceeding 50 mSv.

Earlier dose limit

The earlier dose limit was 150mSv in a year. (Sv is a unit of biologically effective dose. The radiation energy absorbed in a sievert (Sv) is one Joule per kilogramme of material; since the unit is large, a sub-multiple such as one thousandth of a Sv or milliSv —mSv — is normally used).

Several studies over the past few years led the Commission to reduce the dose limit steeply.

There are three main forms of cataract depending on its anatomic location in the eye lens: nuclear, cortical and posterior sub capsular (PSC). Among these, PSC is the least common and is commonly associated with exposure to ionizing radiation. Radiation Effects Research foundation (RERF) describes the formation of radiation cataract thus: “There is a transparent layer of cells covering the interior frontal side of the capsule that covers the eye lens.

This layer maintains the function of the lens by slowly growing toward the centre, achieved through cell division at the periphery. Because irradiation is especially harmful to dividing cells, exposed cells at the equator are most prone to damage.

Unknown reasons

For unknown reasons, damaged cells move toward the rear of the lens before converging on the centre. Such cells prevent light from travelling straight forward resulting in opacity.”

So far, scientists believed that cataract will be formed only after the lens receives a typical radiation dose called the threshold. ICRP assumed that threshold was 2Gy for a single dose and 5 Gy when the exposure occurs in a protracted way.

Not any more. Recent studies appear to show the formation of radiation induced cataracts at much lower doses than the current standards. (Gy is the unit of absorbed dose; the dose is said to be one gray — Gy — when the ionizing radiation energy absorbed per kilogramme of material is one joule).

ICRP now considers that the threshold dose for cataract is 0.5Gy. ICRP also stated that although uncertainty remains, medical practitioners must be made aware that the absorbed dose threshold for circulatory disease may be as low as 0.5Gy to the heart or brain.

“Doses to patients of this magnitude could be reached during some complex interventional procedures, and therefore particular emphasis should be placed on optimization in these circumstances,” ICRP cautioned the specialists. The procedures include angioplasty.

The June 2010 on-line version of Catheterization and Cardiovascular Interventions and October 210 issue of Radiation Research have published studies on increased risk of cataracts among interventional cardiology professionals. Though the numbers of professionals monitored in the studies was limited, the results demand urgent action.

Chernobyl effect

Cataract analysis of 8607 Chernobyl clean up workers,12 and 14 years after exposure, indicated that posterior sub-capsular or cortical cataracts appeared in 25 per cent of the participants (Radiation Research, February 2007). Researchers found evidence of a dose threshold of less than 0.7Gy.

The researchers noted that the workloads tend to increase in catheterization suites. This, together with lack of training in radiation protection and unavailability or non-use of radiation protection accessories may result in doses to the eyes of cardiology professionals sufficient to cause cataracts.

Studies show that leaded glass alone reduced the dose to the lens by 5 to 10 times; scatter-shielding drapes alone reduced the dose rate by 5 to 25 times; using both reduced the dose rate by 25 times or more

In BioMed Central Public Health (2010), Dr Sophie Jacob from the French Institute of Radiological Protection and Nuclear Safety (IRSN) and other specialists listed 14 peer reviewed studies showing evidence for low dose radiation-induced cataracts.

The results of their study on occupational cataracts and lens opacities in interventional cardiology involving 1700 interventional cardiologists in France is expected to be available this year.

The jury is no more out on radiation induction of cataract. The present ICRP recommendations must serve as a wake up call for interventional cardiology and radiology professionals.

Raja Ramanna Fellow, Department of Atomic Energy (ksparth@yahoo.co.uk)

Keywords: International Commission on Radiological Protection, eye lens, radiation dose limit

2011-05-29T11:49:00.000+05:30

Online edition of India's National Newspaper
Thursday, Feb 03, 2011
Finland far ahead in nuclear waste management

— PHOTO:AFP

The solution: A general view of the Olkiluoto 3 European Pressurised Reactor (EPR) being built in Finland. Finland demonstrates that it has in place a popularly accepted technological solution.

Finland consumes nearly 17,000 units of electric power per capita annually; its share of nuclear electricity is about 28 per cent. Though its nuclear power programme is very modest compared to that of U.S. or U.K. it is far ahead in its universally applauded plans for nuclear waste management.
The general refrain of lay public (often reinforced by antinuclear rhetoric) is that there is no ultimate solution for managing high level nuclear waste. Finland demonstrates that it has in place a popularly accepted technological solution.
Finnish programme
Currently, Finland operates four nuclear power reactors with a total installed capacity of 2716 MWe. It produces about 70 tonnes of spent fuel annually. Finland has no plans to reprocess the spent fuel.
Finland started its preliminary preparations for its nuclear waste management shortly before the first reactors started operation 1n 1977-1978. In 1978, the first lot of spent fuel entered the facility for interim storage at Loviisa.
The Nuclear Energy Act 990/1987 passed by its parliament stated that nuclear waste generated in connection with or as a result of the use of nuclear energy in Finland shall be handled, stored and permanently disposed of in Finland.
In 1983, Finland started screening of potential sites for spent fuel disposal. Within the next four years, Finnish scientists started field research in five municipalities for selecting the final disposal site.
Final repository
In 2000, they chose Olkiluoto. They plan to dispose of spent fuel in an underground geological repository. Posiva, a Finnish company which is entrusted with the job has drilled a 6.5 metre –high, 5 m- wide and 5000m long Okalo tunnel. It has removed over 100,000 cubic metre of rock.
The company successfully located the place where no one would ever be likely to dig a deep hole later for exploiting minerals because the place is not mineral-rich. The idea is to abandon forever, the mostly natural, and partly engineered underground repository after filling it.
Canister design
After a few decades of interim storage, the levels radioactivity and heat of spent fuel reduce to about 0.1 per cent of the original values.
It is then encapsulated in a cast iron insert which in turn is covered by a 5 cm thick copper canister. Each insert may carry up to 12 fuel bundles.
They will be placed in neatly bored holes a few metre apart in the underground repository. The gaps between each canister and the hole will be filled with bentonite clay, which swells by absorbing water.
This clay provides cushioning to the canister in case of geological movements and ensures that there are no voids through which water can enter and corrode the container.
Finland hopes to start filling the repository by 2012 and completing it by 2120. They can cover the mouth of the tunnel and forget about it.
Canister integrity
Most of the radioactivity in the spent fuel is due to fission products.
They have a half life of about 30y. In 100,000 years, the radioactivity remaining in the fuel will be negligible. Finnish scientists proved that 1.5 cm of copper cladding would last over 100,000 years. Evidently, 5 cm of copper cladding will be more than adequate.
During the period, an ice age may come and cover the area under 2-3 km of ice. The pressure on the canister due to ice, tightly gripping bentonite clay and ground water may equal that experienced by it at an ocean depth of 4.5 km. Finns proved that their copper cylinders will withstand a pressure three times that before failing.
Waste management cost is manageable. Finland collects a few percentage of the electricity cost per unit of power to manage the waste and deposits it in an independent National Nuclear Waste Management Fund, controlled and administered by the Ministry of Trade and Industry.
The agency estimates and assesses the liability annually.
Finland's nuclear waste management programme was accepted by people because the Government took them into confidence at every stage.
Finland demonstrates that nuclear waste can be managed safely. This issue need not come in the way of harnessing nuclear power.
K.S.PARTHASARATHY
Raja Ramannna Fellow, Department of Atomic Energy
( ksparth@yahoo.co.uk)

Are the units 1 & 2 of Tarapur safe?

2011-05-28T20:59:00.000+05:30

The article titled "Are the units 1 & 2 of Tarapur safe? in The Economic Times (28 May 2011) summarizes the safety upgrades carried out by the Nuclear Power Corporation of India limited (NPCIL) at Units 1 & 2 of TAPS. In view of Fukushima accident NPCIL plans to carry out further steps to enhance safety.

Background radiation and radioactivity in India

2011-05-05T19:05:00.000+05:30

May 5, 2011

Background radiation and radioactivity in India

We live in a sea of radiation. In any city, an unsuspecting owner of a 0.1 acre backyard garden may not know that the top one metre of soil from his garden contains 11,200 kg of potassium, 1.28 kg which is of potassium- 40 (K-40, a radioactive isotope of potassium), 3.6 kg of thorium and one kg of uranium.

These values may be higher or lower depending on the soil. Uranium and thorium decay through several radio-nuclides to lead, a stable element. The presence of radioactive nuclides does not pose any significant risk.

Total dose

The total annual external dose from sources in soil and cosmic rays in Mumbai, Kolkata, Chennai, Delhi and Bengaluru is 0.484, 0.81, 0.79, 0.70 and 0.825 milligray respectively. Gray is a unit for absorbed dose; when the radiation energy imparted to a kg of material is one joule, it is called a gray. Since gray is very large, milligray (one thousandth of a gray), and microgray (one millionth of a gray), are commonly used.

Cosmic rays come from outer space. Their intensity at a place depends on the altitude. Cosmic rays alone contribute 0.28 milligray at the first three cities as they are at sea level; the column of air helps to reduce their intensity. At high altitudes, the protection from the column of air is less.

The cosmic ray contributions are higher at 0.31 milligray and 0.44 milligray respectively at Delhi and Bengaluru as these cities are at altitudes of 216 metre and 921 metre. Air passengers receive 5 microgray per hour from cosmic rays.

Parts of Kerala and Tamil Nadu are high background radiation areas (HBRA) because of the presence of large quantities of monazite in the soil. Thorium content in monazite ranges from 8-10.5 per cent. Researchers found that the radiation levels in 12 Panchayats in Karunagappally varied between 0.32 to 76 milligrays per year; the levels in 90 per cent of over 71,000 houses were more than one milligray per year.

The average value of population dose in HBRA is 3.8 milligray per year. One milligray is the average value for areas of normal background radiation. The units milligray and millisievert are the same in these instances. Study at the HBRA during 1990-99 by the researchers from the Regional Cancer Centre and Bhabha Atomic Research Centre did not show any health effect attributable to radiation.

Radon, which occurs in uranium series present in soil seeps into homes. In temperate areas radon decay products build up in air due to poor ventilation and deliver high doses to the lungs of millions of people. In tropics ventilation is adequate to disperse radon .In the United Kingdom persons in 5 per cent of the homes are exposed to doses above 23.7 mSv/year. One per cent of the population receives doses above 55.8 mSv/year. The highest estimated dose was 320 mSv/year in Cornwall.

All foodstuffs contain potassium-40 (K-40). We need potassium for sustenance. K-40 is 0.012 per cent of potassium. Once ingested, most of the potassium enters the blood stream directly and gets distributed to all tissues and organs.

Homeostatic control

The potassium content in the human body is strictly under homeostatic control. The body retains only the amounts in the normal range essential for its functioning; it is independent of the variations in the environmental levels.

The body excretes excess amounts with a biological half life of 30 days. K-40 delivers a constant annual radiation dose of 0.18 mSv to soft tissue. This dose is unavoidable as potassium is an essential element. Every time we eat a banana, we are introducing 14 Bq of K-40 in to our body. Trucks containing bananas have triggered radiation alarms at border posts in the U.S.

Brazil nut

Brazil nut is probably the most radioactive food. Scientists have measured 700Bq of radium per kg of Brazil nut.

The roots of the Brazil nut tree pass through acres of land; They have a tendency to concentrate barium; along with barium, the roots collect radium as well. Radium appears in the nuts. Many vegetables like brinjal, carrot etc. also contain the radioactive isotope.

Indian researchers have measured polonium-210 in fish and other marine organisms. Our whole body is hit by particles coming from all sides. Radiation is a part of our life. We cannot avoid eating food just because it contains radioactivity

(Raja Ramanna fellow, Department of Atomic Energy)

ksparth@yahoo.co.uk

Keywords: radio activity, potassium, radiation in food

AERB not quite subatomic

2011-04-30T22:04:00.000+05:30

The Economic Times

Tue, Apr 19, 2011 | Updated 08.09AM IST

Atomic Energy Regulatory Board not quite subatomic

By K S Parthasarathy

Recently, the independence of the Atomic Energy Regulatory Board (AERB) and its effectiveness attracted legitimate media scrutiny. Is AERB empowered to act?

The central government set up AERB in November 1983 and empowered it to enforce sections 16, 17 and 23 of the Atomic Energy Act , 1962. These cover control of radioactive substances, administration of the Factories Act, 1948 in the installations of the department of atomic energy (DAE) and enforcement of special provisions of safety. AERB enforces safety-related rules under the Atomic Energy Act.

There is a general perception that AERB is subservient to the department of atomic energy. A review of AERB's functioning does not support this view. Is AERB acting?

From AERB's annual reports, I counted over 50 regulatory actions such as reducing power levels of nuclear power reactors and shutting them down for specified periods to carry out appropriate tests and evaluations, among others which AERB imposed on DAE units.

Nuclear Power Corporation (NPCIL) may have felt that at times AERB has been a little too harsh. NPCIL implemented AERB directives without preferring appeals, even when it involved considerable expenditure.

During 1988 and 1989, AERB restricted the power levels of units 1 &2 of the Madras Atomic Power Station one after the other following failure of their inlet manifolds. It permitted NPCIL to restore power levels in 2003 and 2006, only after substantial upgradations and design changes.

Unit 1 of the Narora Atomic Power Station suffered a serious fire incident on March 31, 1993. AERB decided against the start-up of unit 2 of the Narora Atomic Power Station, pending complete investigation of the fire incident and implementation of the remedial measures recommended by two specialist committees set up by NPCIL and AERB,

The board ordered sequential shut down of each unit of the pressurised heavy water reactor (PHWR) stations for inspection of its turbine, generator and associated components to assess its state of health and fitness for continued operation and to modify the turbine roots. NPCIL complied with the directive.

In 1994, subsequent to the failure of the inner containment dome of unit 1 of the Kaiga Atomic Power Project, AERB suspended the civil construction activities related to the inner containment domes of Kagia unit 2, and units 3 and 4 of the Rajasthan Atomic Power Project. AERB lifted the hold only after satisfactory resolution of related safety matters.

In 2004, AERB prescribed 'formal and elaborate retraining and relicensing of all the frontline operating staff and the station management personnel' following a safety-related incident at the Kakrapar Atomic Power Station.

In 2007, the AERB withdrew the construction licence of units 5 and 6 of the Rajasthan Atomic Power Project when it found poor industrial safety status. It lifted the hold only after NPCIL ensured enhanced safety arrangements.

As directed by AERB, specialists re-evaluated the seismic safety of units 1 and 2 of the Tarapur Atomic Power Station which was designed as per the standards prevailing in 1969. NPCIL remedied the shortfalls by following international practices. NPCIL installed seismic sensors at all plants as stipulated by the AERB.

AERB imposed restrictions on many hospitals and other installations. AERB took action against the installations of the Oil & Natural Gas Commission, when it found lapses.

The list of AERB actions is indicative and not exhaustive. AERB enjoys functional autonomy; it takes its own decisions on merit. I was a witness to or participated in AERB activities closely since 1984. I do not recall a single instance in which DAE or others influenced AERB.

The five-member board has more members from outside the AEC family, it reports directly to the Atomic Energy Commission (AEC) and not to an individual. AEC has the status of the government of India.

AERB has many specialists from outside the DAE in its committees. However, a robust regulatory system cannot rely on good intentions alone. AERB must be made a statutory organisation.

Recently, the Prime Minister stated that AERB's legal status will be enhanced. Some critics feel that ARRB "merely serves as a lapdog of the Department of Atomic Energy". Though the statement makes good copy, many regulatory actions of AERB from 1983 do not support the criticism. They show that a lapdog may just bark, but AERB actually bites.

I hope that AERB will continue to function effectively as it always did regardless of the perceived infirmities of its legal status.

(The author is a former secretary of the Atomic Energy Regulatory Board, government of India)

2011-02-25T10:51:00.001+05:30

Published: January 19, 2011 23:43 IST | Updated: January 19, 2011 23:43 IST January 19, 2011

CT scans best to uncover body packed drugs

http://www.thehindu.com/health/medicine-and-research/article1103201.ece

The Hindu THE CAUTION: Though CT can be used for detecting concealed drugs, low-dose protocols are needed to make it safer for people undergoing the procedure. Photo: K. Murali Kumar

CT has a sensitivity of 100 per cent, while others like digital radiography and digital X-ray have only 85 per cent and 70 per cent respectively

During 1924, Captain T W Barnard, Director, Erstwhile Institute of Radiology at the General Hospital, Madras, helped the police to locate a gold chain in the stomach of a thief by x-raying him.

A few years later, Barnard found precious stones secreted in small cavities inside the cheeks of the women of a band of criminals by x-raying them; police suspected that they stole a large quantity of jewels. Identifying drugs in place of gold will be difficult.

Body packing

The US Customs and Border Patrol (CBP) seize over a million pounds of drugs (mainly marijuana, cocaine and heroin) annually. Eighty percent of the smugglers caught by CBP practice ‘body packing' of these illegal narcotics.

The May 2008 issue of the Applied Radiology describes the practice of body packing as the trafficking of illicit drugs within the gastrointestinal tract or vagina. According to the journal, body packers are also known as ‘swallowers,' ‘internal carriers,' ‘couriers' or ‘mules.'

Detects cocaine

A study presented recently at the annual meeting of the Radiological Society of North America (RSNA) identified computed tomography (CT) as the best way to detect cocaine in the body of a ‘mule.'

Dr Patricia Flach, a radiologist at University Hospital of Berne and Institute of Forensic Medicine of Berne in Switzerland and colleagues analyzed images from 89 exams using various imaging methods (CT:27; Digital X-ray: 50 and low-dose linear slit digital radiography (LSDR):12) and performed on 50 suspected drug ‘mules' over a three-year period at University Hospital.

The study group included 45 men and five women aged between 16 and 45. Researchers identified forty-three of the suspects as drug mules. They compared the radiologic findings with a written record of the drug containers recovered from the faeces of suspects.

CT imaging the best

CT imaging allowed the physicians to see all the drug containers, especially when they knew what to look for. Thus the sensitivity of CT is 100 per cent. LSDR had a sensitivity rate of 85 per cent; digital x-ray was able to identify the presence of cocaine containers only 70 per cent of the time.

Intestinal contents are messy and non-uniform in consistency. According to Dr Flach, there were positive findings on CT that were clearly not detectable on conventional x-rays due to overlap of intestinal air, faeces or other dense structures.

The coating and manufacture of the containers changed their appearance, especially on CT images. Rubber-coated condoms filled with cocaine appeared hyper-dense, or white, on CT, while other containers of similar size with plastic foil wrapping appeared iso- to hypo-dense or grey to black.

Dr. Stephen J. Taub, Division of Toxicology, Department of Emergency Medicine, Beth Israel Deaconess Medical Centre, Boston, USA and colleagues stated that body packers usually carry about one kg of drug, divided into 50 to 100 packets of 8 to 10 g each. Smugglers have devised automatic processes to pack drugs densely into latex sheaths or condoms.

False negatives

Writing in The New England Journal of Medicine, they noted instances in which physicians interpreted two plain abdominal radiographs as negative. The suspects subsequently passed 106 and 135 packets.

Plain abdominal radiographs may be useless to identify drugs in the ‘mules.'

When the law enforcing authorities suspect an individual of being a drug ‘mule,' they often seek the help of radiologists to detect quickly the presence of drugs concealed in the body.

According to the researchers, cocaine containers, which may be swallowed or inserted in the vagina or rectum, can be as large as a banana or as small as a blueberry.

“In these cases it is important for us to know that we have identified all the drug containers in a body, both for legal purposes and for the health of the patient,” Dr. Flach said.

“However, there was no research telling us which imaging modality was best in detecting cocaine containers in the stomach, intestines or other body orifices.”

Higher dosage

CT exposes the suspects to higher doses of ionizing radiation. It is obviously of concern while imaging healthy people.

“CT is the way to go," Dr. Flach said. "But low-dose protocols need to be implemented to ensure the safety of the people undergoing the procedure,” she cautioned.

Raja Ramanna Fellow, Department of Atomic Energy ksparth@yahoo.co.uk

50 years of CIRUS: some unforgettable memories

2010-12-23T13:43:00.000+05:30

S & T

Published: December 23, 2010 01:41 IST | Updated: December 23, 2010 01:57 IST December 23, 2010

50 years of CIRUS: some unforgettable memories

K.S. PARTHASARATHY

OLD WARHORSE: Research Reactor CIRUS at the Bhabha Atomic Research Centre at Trombay. Photo: V.V. Krishnan

On December 18, the scientists and engineers in the Department of Atomic Energy (DAE) celebrated the Golden Jubilee of CIRUS and the Silver jubilee of DHRUVA. The organizers invited everyone who was associated with the two research reactors. It was an emotional homecoming for many, especially for those who retired decades ago.

The 40 MW research reactor attained criticality on 10{+t}{+h} July 1960. It was constructed under Canadian assistance. India and Canada shared the cost of about $14.14 million. CIRUS, the workhorse of BARC is a symbol of the advanced developments in nuclear science, engineering and technology in India.

Dr Bhabha chose this heavy water moderated, uranium metal fuelled reactor as it would be a powerful tool for research. Also Dr W.B. Lewis, the eminent scientist who led the designers of the reactor was close to him in his Cambridge days.

Veterans recalled the teething problems they faced, the ways in which they solved them and their unforgettable memories. The 188-page commemorative booklet which describes them is a lucidly written, technical document, an A to Z cookbook on research reactor operation and maintenance!

Priceless experience

The reactor operation and maintenance group acquired priceless experience by studying the failure data of components such as valves.

Floating materials, mainly plastic waste and seeds and leaves from ever expanding mangroves, clogged the travelling water screens in the sea water inlet system; silt accumulation in the gland vent ports damaged the pumps. Scientists addressed these issues promptly.

“ In a hurry to start the reactor early, Bombay municipal water was charged to the high head storage tank ( ball tank) and was used in the re-circulating coolant water circuit” Shri S.M. Sundaram, former Director, Reactor Operation and Maintenance Group (ROMG) recalled. The total dissolved solids (TDS) such as silica in water got deposited on the fuel cladding, reducing coolant flow and damaging many of them at higher power level.

The Canadians did not face such a problem in their reactor; they used fresh water from Ottawa River. Sundaram and his team purified water using ion exchangers and solved the problem.

He remembered that then he worked against the orders from their superiors. Bhabha tacitly supported them. “…he said that there may be rare occasions when one may need to disregard the orders of his superior, for a good cause”.

By October 1963, they could raise the power level to 40 MW.. “ever since, CIRUS has been the workhorse of Indian atomic research programme”, Shri N. Veeraraghavan, former Associate Director, ROMG recalled.

He remembered that Dr Bhabha addressed a meeting in the indoor games room in the Old Yacht Club Building, which was attended by CIR project related scientific community sometime end of 1959 or early 1960.

“Bhabha expressed full confidence in the ability of Indian engineers in the production of indigenous, pure natural uranium and its fabrication into fuel rods for the initial loading of the CIRUS reactor”, Shri Veeraraghavan said .

Very bold commitment

“ As I see it today, this was a very bold commitment at that time, which ended happily for all, especially the chemical and metallurgical engineering staff that really worked hard and met the commitment with the loading of indigenous uranium fuel for the first “criticality” of CIRUS reactor,” he added

Most of the members of the newly recruited scientific and engineering staff for CIR operations sent for training to Canada during 1956-1957 came from very conservative backgrounds. They were from different regions of the country and spoke different languages. Most of them were strict vegetarians.

Dr M.R. Srinivasan, former Chairman, Atomic Energy Commission (AEC), delivered a few lectures to them. Bhabha asked him to take them to the Taj Hotel so that they would learn to use knife and fork before going to Canada for further training!

Dr P.K. Iyengar, former Chairman, AEC, recalled that the training school programme which Bhabha spearheaded helped national integration; it brought people from different parts of the country together.

Heartbroken

“I am truly heartbroken to learn that this old workhorse will be put to sleep at the end of this year for reasons that are anything but technical” the words of Shri S.K. Sharma, former Director, Reactor Group, truly reflected those of many others present.

“But then those are the ways of the world that we live in,” he consoled everyone.

In his inaugural address Dr R.K. Sinha, Director, BARC, stated that the CIRUS reactor provided research and development inputs to the nuclear power programme in the country.

It provided a platform to train engineers and technologists in the area of reactor management.

“This is an occasion to reflect on the past and to pay our gratitude to our elders” Dr Srikumar Banerjee, Chairman, AEC, said while addressing the gathering.

K.S. PARTHASARATHY, Raja Ramanna Fellow, DAE

(ksparth@yahoo.co.uk)

Keywords: CIRUS, Department of Atomic Energy

CT: cancer risks for the elderly

2010-12-02T18:14:00.002+05:30

Online edition of India's National Newspaper
Thursday, Dec 02, 2010

The study showed cancer incidence from CT scans was less threatening

— photo: K. Murali Kumar

The focus: The study estimates cancer risk to persons above 65.

In a paper presented at the 96 {+t} {+h} Scientific Assembly and Annual Meeting of the Radiological Society of North America, Dr Aabed Meer and co-workers at the Stanford University at Palo Alto, California, have claimed that the risk of developing radiation-induced cancer from computer tomography (CT) may be lower than previously thought.
It is the first time in many years that a scientific study showed that the impact of CT on the incidence of cancer was less threatening! But the RSNA paper does not state that CT scans are risk free. The paper has not undergone any peer-reviewing as it was presented at the RSNA meeting, and not published in a peer-reviewed journal.
The study has certain other limitations. It estimates cancer risk to persons above 65 years. The views of learned bodies and professional associations on the study are yet to be published.
This study is statistically respectable as it included 10 million records of patients from 1998 to 2005. Based on Medicare database, they analyzed the distribution of CT scans, determined the radiation doses associated with them and estimated the associated cancer risk in a population of older adults. Medicare is a social insurance program administered by U.S.government, providing health insurance coverage to people who are aged 65 and over, or who meet other special criteria (Wikipedia).
The researchers included the data from two study groups; 5, 2767,230 records from 1998 through 2001 and 5,555,345 records from 2002 through 2005. They analyzed the number and types of CT scans that each patient received to find out the percentage of patients exposed to “low” radiation doses of 50 mSv to 100 mSv and “high” radiation doses in excess of 100 mSv (Sv is a unit of biologically significant dose and it involves the absorption of one joule per kg of radiation energy; mSv is a thousandth of a Sv).
They calculated the number of cancers that may be induced by using standard cancer risk models.
CT scans of the head numbered 25 per cent of the examinations in the first group and 30 per cent in the second. They found out that abdominal CT exposed patients to the greatest proportion (nearly 40 per cent) of doses in each group. The second and third largest sources of radiation were imaging of pelvis and chest
From 1998 to 2001, 42 per cent of the patients underwent CT scans; the corresponding percentage for 2002 to 2005 was 49. The researchers also found that the percentage of patients exposed to radiation doses in both the low and high ranges nearly doubled from the first group to the second. This was consistent with the increasing use of high speed CT in patient diagnosis and management.
They estimated the cancer incidence associated with exposure to radiation from CT to be 0.02 percent and 0.04 percent of the two groups respectively. The authors found a significantly lower risk of developing cancer from CT than the previous estimates of 1.5 per cent to 2 per cent of the population.
The study which gave higher numbers refers to a paper published by Drs David Brenner and Eric Hall, researchers in the Columbia University Medical Centre, New York in the New England Journal of Medicine (November 29, 2007)
This paper became very controversial. The American College of Radiology, the Radiological Society of North America and the Association of Physicists in Medicine reacted to the paper with predictable alacrity. These associations argued that the conclusions of the paper may scare away patients from clinically needed CTs.
The NEJM study got extensive media coverage as it focused attention on the overuse of CT. It was then estimated that one million children and 20 million adults in the USA undergo unnecessary CT scan procedures annually.
Medical radiation procedures must be carried out only if they are justified. Physicians must ensure that radiation doses are As Low As Reasonably Achievable (ALARA) without compromising clinical needs.

K.S. PARTHASARATHY
RAJA RAMANNA FELLOW DEPARTMENT OF ATOMIC ENERGY

( ksparth@yahoo.co.uk)

Radiation exposure: cancer risk in middle age

2010-11-04T12:08:00.003+05:30

Published: November 4, 2010 16:50 IST | Updated: November 4, 2010 16:51 IST November 4, 2010

Radiation exposure: cancer risk in middle age

K.S. PARTHASARATHY

Share · print · T+

AFP Stark reminder: The Atomic Bomb Dome is silhouetted in the sky beside the Peace Memorial Park in Hiroshima. Researchers reanalyzed the Japanese A- bomb survivor data and assumed two different pathways through which radiation exposure can lead to cancer.

Study of the data on A-bomb survivors continues to throw surprises.

An interesting analysis published in the Journal of the National Cancer Institute (25 October 2010) revealed that contrary to common assumptions, the risk of cancer associated with radiation exposure in middle age may not be lower than the risk associated with exposure at younger ages. The study is important as most of the diagnostic studies and occupational radiation exposures occur at middle age. However, if all radiation exposures are As Low As Reasonably Achievable (ALARA), there is no reason to worry.

Latent period

Children are more sensitive than adults to the effects of radiation as the cells in the body are dividing rapidly. Generally, cancer is induced after a latent period. Since children have longer life than adults, they have a greater chance of developing radiation-induced cancer than adults. Some data also suggest that, in general, the older a person is when exposed to radiation, the lower their risk of developing a radiation-induced cancer.

Recent analysis of the statistical evidence from long-term studies of atomic bomb survivors in Japan indicates that for radiation exposure after about age 30, the risk of developing radiation-induced cancer does not continue to decrease. This was not consistent with earlier studies.

Two pathways

Dr.David J. Brenner, at Columbia University in New York, and colleagues reanalyzed the Japanese A- bomb survivor data; they assumed two different pathways through which radiation exposure can lead to cancer.

Firstly, there may be the initiation of gene mutations that convert normal stem cells to premalignant cells that could eventually lead to cancer.

Second pathway

The second pathway assumes the existence of radiation induced promotion, or expansion, of the number of existing premalignant cells in the body. Researchers believe that the initiation effect is more likely to play a role in children than in adults; because cells initiated at an early age have a longer time available to proliferate and progress to cancer.

The promotion effect is more likely to be important for radiation exposures in middle age, because the adult body already contains larger numbers of premalignant cells.

Researchers developed a model based on these biological effects and applied it to the Japanese atomic bomb survivor data. The model reproduced the cancer risk patterns associated with age at radiation exposure observed in these survivors.

They applied the same model to predict cancer risks as a function of age in the U.S. population and found that the cancer risks predicted by the model were consistent with the data in the age range from about 30 to 60.

The authors argued that cancer risk after exposure in middle age may increase for some tumour types; this was contrary to what was known earlier.

Dr John D. Boice of the International Epidemiology Institute, Rockville, Md., and Vanderbilt University, Nashville, cautioned that there are uncertainties in generalizing the Japanese data to a U.S. population (Editorial in JNCI). According to him other data and other models contradict the results of this study.

Provocative hypotheses

He conceded that this biology-based model “raises provocative hypotheses and conclusions that, although preliminary, draw attention to the continued importance of low-dose radiation exposures in our society.”

Dr Brenner and colleagues concluded that overall, the weight of the epidemiological evidence suggests that for adult exposures, radiation risks do not generally decrease with increasing age at exposure, They noted that the mechanistic underpinning described here provides this conclusion with some biological plausibility.

Dr Brenner's papers may appear controversial; In 2003, he along with 14 eminent radio-biologists and epidemiologists concluded thus: “Given that it is supported by experimentally grounded, quantifiable, biophysical arguments, a linear extrapolation of cancer risks from intermediate to very low doses currently appears to be the most appropriate methodology.

This linearity assumption is not necessarily the most conservative approach, and it is likely that it will result in an underestimate of some radiation-induced cancer risks and an overestimate of others” (Proceedings of the National Academy of Sciences, 2003).

The JNCI paper throws fresh light on the topic.

K.S. PARTHASARATHY

Raja Ramanna Fellow, Department of Atomic Energy

(ksparth@yahoo.co.uk)

Keywords: radiation exposure, cancer, atomic bomb survivors

Radiation exposure and heart disease risk

2010-10-14T12:39:00.001+05:30

On October 7, 2010, the UK Health Protection Agency published a report titled Circulatory Disease Risk prepared by its Advisory Group on Ionizing Radiation (AGIR). The report said that there is a clearly demonstrated risk for cardiac disease due to radiation exposures above 0.5Gy.

This has clear implications in radiation therapy. I brought the HPA report to the notice of a few medical physicists and radiation oncologists. The latter mostly belonged to the office bearers of the Association of Radiation Oncologists of India. I requested them to examine whether this report will help them to modify their working practices so that cancer patients may derive some benefits

Dr K.S.Parthasarathy

Thursday, Oct 14, 2010

Radiation exposure and heart disease risk

It would be appropriate to incorporate circulatory disease risks while estimating risks to individuals exposed to doses above 0.5 Gy

— Photo: V. Ganesan

The link: The expert group highlighted the need for further research to better understand the link between radiation exposure and circulatory disease.

The study of biological and medical effects of ionizing radiation continues to be enigmatic. After over ten decades of intensive and extensive studies, specialists concluded that high doses of radiation may cause cancer in the exposed individual.
At low doses there is some uncertainty; however in the field of radiation protection, specialists assume that radiation doses at all levels are carcinogenic.
Evidence on links
Evidence on links between radiation exposure and non cancer diseases such as heart disease has emerged more recently.
For many years, scientists suspected these links. On October 7, 2010, the UK Health Protection Agency's (HPA) Advisory Group on Ionizing Radiation (AGIR) published a report titled “Circulatory Disease Risk”, reviewing the recently published epidemiological studies and experimental work on the risks and potential causes of circulatory diseases following exposures to ionizing radiation.
The report urged the clinicians who use medical radiation procedures in diagnosis and therapy to examine their working practices.
AGIR recommended that where possible they should keep the radiation doses to the brain and heart of the patients as low as possible while maintaining essential medical benefits (HPA Release, October 7, 2010).
The expert group also highlighted the need for further research to better understand the link between radiation exposure and circulatory disease.
The AGIR concluded that radiation exposure to the heart and circulatory system can occur in several contexts. For instance, the circulatory system of the entire population is exposed to a part of the natural back ground radiation. These are low levels.
“Radiation workers may receive higher doses and those receiving medical diagnostics, some medical interventional radiological procedures and, particularly, radiotherapy may receive doses to the circulatory system, or parts of it, up to the level of several gray (absorbed dose)”, the specialist group added
(gray-Gy- is a unit of absorbed dose; a tissue is said to receive one gray of dose, when the energy due to ionizing radiation absorbed by it is one joule per kilograme. AGIR defined doses thus: Very high – doses above 15 Gy; High – doses of 5–15 Gy; Medium –doses of 0.5–5 Gy; Low – doses below 0.5 Gy)
“Even small relative risks due to radiation could have a major impact…….. as circulatory diseases are already common in the population”, the specialists cautioned. For instance, circulatory diseases are common in Western populations and are the main cause of death in the UK, accounting for some 193,000, or 34 per cent, of deaths each year.
AGIR noted that evidence from radiotherapy follow-up studies and from experimental animal models indicates that irradiation at high and very high doses increases circulatory disease risk. But the use of cardio-toxic drugs in chemotherapy complicates the precise estimation of risk.
Clinicians have detected a statistically significant increase in the risk of certain circulatory diseases (notably, stroke, heart disease and specifically ischemic heart disease) at low and moderate dose (below 5 Gy) epidemiological studies, notably the atomic bomb survivor studies and nuclear worker studies.
While heterogeneity between the studies is considerable, statistically significant excess risk can be detected at around 0.5 Gy; contributory risk factors such as cigarette smoking, diet and alcohol consumption may confound these studies.
Emergence unlikely
Convincingly strong association with, circulatory disease below doses of 0.5 Gy is considered to be very unlikely to emerge from human population studies in the near future. Insights from mechanistic experimental studies may eventually show whether cardiac diseases may be caused by low radiation doses.
According to AGIR, there is currently little evidence to justify the inclusion of circulatory disease while calculating radiation risk at doses of 0.5 Gy and below. This is a pointer towards more research. Radiation protection specialists can breathe easy.
AGIR concluded that it would be appropriate to incorporate circulatory disease risks when we estimate health risks to individuals exposed to doses above 0.5 Gy. This is a clear message to radiation oncologists. Dedicated use of Intensity Modulated Radiotherapy (IMRT), if available, may be useful.
The Association of Radiation Oncologists of India may review the HPA report and examine how best they may modify their practices wherever appropriate, to give maximum benefits to their patients.

K. S. PARTHASARATHY

Raja Ramanna Fellow, Department of Atomic Energy
( ksparth@yahoo.co.uk)

Lessons to belearnt from Delhi radiation incident

2010-09-09T12:08:00.000+05:30

The Hindu

Date:15/04/2010 URL: http://www.thehindu.com/thehindu/seta/2010/04/15/stories/2010041551311400.htm
________________________________________
Back Sci Tech

Lessons to be learnt from Delhi radiation incident

Photo: K. PIchumani

The source: Virtually all instances of steel contamination seem to have been caused by radioactive sources which came with imported scrap. —
At 12:45 hrs on April 7, 2010 the Atomic Energy Regulatory Board (AERB) received a fax message from Indraprastha Apollo Hospital, Delhi stating that a scrap metal dealer admitted to the hospital showed symptoms suspected to be caused by radiation exposure.
Six more workers who also exhibited similar symptoms were admitted elsewhere. On receiving the information, two AERB officers who were already in Delhi inspected the shop and its surroundings, identified high radiation levels and promptly shielded some suspected high radiation locations with metal sheets to reduce the radiation levels.
As per the procedure in place, a team of scientists from Bhabha Atomic Research Centre (BARC)and the Narora Atomic Power Station , mobilized by the Crisis Management Group of the Department of Atomic Energy (DAE) and scientists from AERB visited the site again and restored normalcy by safely removing the sources into appropriately shielded containers. By April 9, 2010, the radiation levels at the site became normal background radiation levels.
“It was indeed a difficult operation; we collected cobalt-60 sources of high strengths in the form of wires under trying circumstances and secured them in special containers. We instituted strict dose control procedures which ensured that the radiation doses to us were within limits,” said Dr. K.S.Pradeep Kumar, Senior Scientist and Head, Emergency Response System and Methods Section.
“We learnt a few lessons. The team from Narora brought many tools and accessories; their support proved to be very crucial,” he clarified. He paid compliments to the excellent cooperation extended by the Delhi police.
A handful of radiation incidents in which persons got exposed to very high radiation doses occurred in India. Most of the cases were because of gross violation of safety procedures in handling industrial gamma radiography sources.
In the most serious case, a railway gang man received high dose as he kept gamma source in his pocket for a few hours. The source was lost in transit because of negligence of radiation workers in a company. Follow up action led to the winding up of the company.
The victim pocketed the shining object assuming that it is valuable. He was admitted into BARC Hospital initially for three months and was followed up for one and a half years. He survived after several skin drafts and other procedures.
The Delhi incident was a serious one. That such incidents were rare would be poor consolation for those seven persons who were exposed to radiation. There must be zero tolerance to such events.
AERB had suggested several preventive measures ( The Hindu, Nov 13, 2008). In the light of a few steel contamination incidents, AERB proposed to put in place a multi layered radiation check system ( The Hindu, February 26, 2009). These need closer review, strengthening and more effective enforcement.
Many scrap dealers have bought radiation monitors. The proposal to erect radiation monitors at major ports is yet to be implemented. Since virtually all instances of steel contamination seem to have been caused by radioactive sources which came along with imported scrap, radiation monitors must be installed urgently at all ports. The radiation incident at Delhi must be considered as the final wake up call. There are plans to equip selected police stations in major cities with radiation monitors. The task is humongous but achievable through dedicated efforts.
Radiation exposure from “orphan sources” was a topic of discussion in many meetings held by the International Atomic Energy Agency (IAEA) since 1998.An initial review indicated that, more than 110 countries may not have minimum infrastructure to properly control radiation sources (IAEA, 1999).
Since 1990, 300 radioactive sources were recovered from Georgia. There were instances in which intense radiation sources used in agricultural research such as mutation studies were found abandoned in trucks
In the United States alone, the Nuclear Regulatory Commission (NRC) annually receives about 200 reports of lost, stolen or abandoned radioactive sources. This is disconcerting as U.S. has a stringent regulatory system. AERB receives less number of reports annually, presumably because we have far less number of sources in use. Also as in U.S., AERB has a very effective system to track high intensity sources.
K.S. PARTHASARATHY
FORMER SECRETARY, AERB
ksparth@yahoo.co.uk
© Copyright 2000 - 2009 The Hindu

New Health Studies on A-bomb Survivors

2010-09-09T12:03:00.000+05:30

New Health Studies on A-bomb Survivors

Published on: August 28, 2010 - 23:04

Cataract risk for unprotected interventional cardiology personnel

2010-09-08T17:52:00.007+05:30

September 1, 2010

Cataract risk for unprotected interventional cardiology personnel
K. S. PARTHASARATHY

ULTRA SENSITIVE: The eye lense is one of the most radiosensitive of the tissues. Photo: K. Ananthan
Now it is official. In two separate studies, researchers supported by the International Atomic Energy Agency (IAEA) recently concluded that interventional cardiologists and associated workers who have not used radiation protection accessories have significantly elevated incidence of radiation associated eye lens changes; and that there is urgent need to educate them in radiation protection to reduce the likelihood of cataract.
Published studies
Radiation Research (June 28, 2010) and Catheterization and Cardiovascular Interventions (June 14, 2010) two peer reviewed journals have published these studies.
There are three main forms of cataract according to its anatomic location: nuclear, cortical and posterior sub capsular (PSC). Among the three forms of age-related cataract, PSC is the least common but this form is most commonly associated with exposure to ionizing radiation. Researchers in both studies demonstrated a dose-dependent, increased risk of posterior lens opacities for interventional cardiologists and nurses when they did not use radiation protection accessories.
Larger cohort needed
Though a larger cohort is needed to confirm the findings, the results suggest that radiation protection measures for eyes must be in place.
In both studies, two independent specialists each trained in the recognition and evaluation of characteristic, radiation-induced lens changes, examined the eyes of each participant after full dilation.
The study published in Radiation Research showed that the interventional cardiologists have 3.2 times more risk than for unexposed controls. For nurses and technicians, the relative risk was 1.7 times more.
The study groups consisted of 116 exposed individuals (interventional cardiologists: 58 and associated workers :) and 93 similarly aged non-exposed individuals.
The paper published in Catheterization and Cardiovascular Interventions showed that the relative risk for interventional cardiologists was 5.7 and for nurses and paramedical staff, it was five, compared to unexposed controls. This group contained 67 physicians and nurses and 22 age and sex matched health care professionals not working in interventional medicine.
“The lens of the eye is one of the most radiosensitive tissues in the body and exposure of the lens to ionizing radiation can cause cataract” the researchers wrote in Radiation Research.
“Ionizing radiation exposure to eye lens results in characteristic progressive changes leading to opacification or clinical cataract. While initial, early stages of such opacification may not cause visual disability, the severity of such changes increases progressively with dose until vision is impaired and cataract extraction surgery is required,” the researchers warned.
“Because of its location along the visual axis of the lens, relatively minor PSC can have a great impact on vision,” the researchers cautioned.
Cataract sets in early, if the dose is larger. Cumulative x-ray doses to the lenses of interventional cardiologists and staff can be very high. They often remain close to the patients for several hours a day during cardiac interventional procedures. Patients scatter x-rays.
Combining doses
The researchers evaluated eye lens dose of each participant by combining doses measured from several catheterization laboratories with the subject's reported annual workload (number and kind of procedures carried out).
In 2007, the International Commission of Radiological Protection (ICRP), in its latest recommendation, reiterated the suggestion from recent studies that the lens of the eye may be more radiosensitive than previously considered.
Surveys during various IAEA training courses in which cardiologists from 56 countries attended indicated that only 33-77 per cent interventional cardiologists used dose measuring badges routinely. They did not use protective accessories universally.
An AERB workshop on “Radiation safety in interventional radiology including cath lab” in April 2009 highlighted the need for formal training in this important area. Taking into account its potential to deliver high radiation doses, the Atomic Energy (Radiation Protection) Rules 2004 prescribed that all such equipment must have a “license”, the highest form of regulatory documentation and control.
Interventional cardiologists must receive appropriate training and accreditation to use radiation equipment optimally without undue risk. AERB and the relevant professional associations must take the lead in achieving this objective.
Let us learn from the experience of advanced countries which acted promptly when patients suffered skin injuries. The new findings on cataract must speed up a comprehensive programme of training.
The training material is freely available at: http://rpop.iaea.org/RPOP/RPoP/Content/AdditionalResources/Training/1_TrainingMaterial/Cardiology.htm
Raja Ramanna Fellow, Department of Atomic Energy
(ksparth@yahoo.co.uk)
Keywords: Radiation risk, cataract, International Atomic Energy Agency, cardiologists, eye lens changes, Radiation Research, Catheterization and Cardiovascular Interventions

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Findings on artery plaque

2010-08-12T15:34:00.002+05:30

Tuesday 10 August 2010

Medical Research
Findings on artery plaque

Haim Shmilovich and his fellow researchers from Heart Institute, Cedars-Sinai Medical Centre, Los Angeles, California found that, besides the degree of blockage, the composition of the plaque causing the blockage has significant impact on blood flow through coronary artery, writes K S Parthasarathy

If a person is diagnosed as suffering from heart disease, the current medical practice is to carry out an invasive procedure such as angioplasty or stent-placement or open heart surgery as appropriate. A study presented at the 57th Annual Meeting of the Society of Nuclear Medicine in June at Salt Lake City, USA is challenging this practice.

People with similarly blocked arteries can experience vastly different symptoms. Nobody knows why.

Dr Haim Shmilovich and his fellow researchers from Heart Institute, Cedars-Sinai Medical Centre, Los Angeles, California found that, besides the degree of blockage, the composition of the plaque causing the blockage has significant impact on blood flow through coronary artery. May be this is why two people with similarly blocked arteries can experience vastly different symptoms.

According to Dr Mason W Freeman, Associate Professor, Harvard Medical School coronary artery disease (CAD) begins when plaques build up in the arteries.

Plaque deposit hardens later

He vividly described the process. Initially, the plaque deposit may be soft and mushy; later it hardens, narrowing the artery. Blood flow to the heart decreases; at the beginning, this reduction is not severe enough to compromise heart muscle function or to produce any symptom.

Later on, the plaque may enlarge further reducing the blood flow. After a critical point, the heart muscle no longer gets adequate oxygen delivery when it is working vigorously. A prolonged or complete interruption will kill myocardial cells and cause a heart attack.
The plaques are not homogenous. They contain fat and other substances including calcium. Plaques vary in size. Even very young persons may have early stage plaques. When plaques cause blockade of the arteries, symptoms develop .When the blockade is 70% or more physicians carry out invasive procedures to reduce symptoms and potentially to prevent heart attacks. How can we determine the composition of the tiny deposits of fat in the blood vessel of a few millimetres diameter deep inside a living person? Researchers use coronary CT angiography (CCTA) for this and to find the degree of blockage it causes.

Use of an intravenous dye

The coronary CT angiography uses an intravenous dye which contains iodine and CT scanning to image the coronary arteries. Physicians measure the relative blood flow to different regions of the heart by myocardial perfusion imaging (MPI). During myocardial perfusion imaging, the physician administers a radio-pharmaceutical intravenously to depict the distribution of blood flow nourishing the myocardium- the middle of the three layers forming the wall of the heart.

Perfusion imaging identifies areas of reduced myocardial blood flow associated with ischemia or scar. Physicians can assess the relative regional distribution of perfusion at rest, cardiovascular stress, or both. They also perform imaging during chest pain of unknown etiology, such as in the coronary care unit or emergency department.

They found that clinicians can more accurately determine a patient’s risk of reduced blood flow to the heart muscle by identifying three plaque characteristics: the presence of a fatty core, signs of spotty calcifications and enlargement of the arterial wall from “positive remodelling”, which means that the body has responded to arterial damage by altering the structure of the artery. Researchers noted that either individually or combined, the presence of these characteristics can predict reduced blood flow to the heart muscle, which could lead to symptoms including heart attack.

They imaged 34 patients without known coronary artery disease using CCTA and MPI to determine the presence of adverse plaque characteristic and blood flow. All patients had severe (70 to 89 per cent) blockage in the beginning or middle section of a major coronary artery on CCTA.

A third-party expert evaluated adverse plaque characteristics on CCTA; an automated computer -based analysis carried out the myocardial perfusion imaging.

When imaged with MPI, over 38 per cent had significantly limited blood flow to the heart muscle.

In the arteries with plaques with a fatty core, significant ischemia (condition in which blood flow and hence oxygen supply is reduced) of the heart muscle occurred at a much higher and statistically significant frequency (80 per cent) than those without fatty core (21per cent).

When specialists found multiple adverse plaque characteristics in a plaque, that was associated with higher degrees of significant ischemia.

Findings could redefine treatment

The researchers claimed that if they can determine certain characteristics of the coronary artery plaque, they can predict whether a patient’s symptoms are due to limitation of blood flow to the heart.

They believe that with more studies, their findings may change treatment planning for patients with severe but stable coronary artery disease by helping them determine which patients could be treated just as effectively with medications and life style changes, thereby avoiding unnecessary invasive angioplasty and bypass surgery. The study is promising. A major problem with all medical imaging modalities is that the technology advances with unbelievably astonishing speed; the clinical use lags disappointingly behind.

(The writer is Raja Ramanna Fellow, Department of Atomic Energy.)

Laser pointers may damage vision

2010-08-06T15:58:00.000+05:30

THE TRIBUNE

SCIENCE & TECHNOLOGY
Friday, August 6, 2010, Chandigarh, India

Laser pointers may damage vision
K.S. Parthasarathy

AS Dr.Timothy B L Ho, Firmley Park Hospital NHS Foundation Trust, Surrey, UK entered his house one evening, his seven year old son flashed a laser pointer on his face. The eye injury, he suffered, was not apparent immediately.
Four days later, he developed an area of partial alteration of his field of vision His son found the device, a gift from a drug company, on his father’s desk. Laser pointers which are common place now can damage vision if handled carelessly.
“My vision took several months to recover and initially I was very worried”, Dr Ho wrote in The British Medical Journal, (BMJ, 29 June 2010), when Drs Ziahosseini, Doris and Turner published in the BMJ, a laser injury case suffered by a teenager.
He bought a green diode laser pointer over the internet and shone the laser beam into his eyes while playing with it. He had no previous medical or ophthalmic problems. Tests confirmed disturbance of his retinal pigment epithelium; it took two months to improve his clearness of vision.
In yet another instance, while on the school bus, a friend attempted to determine whether a laser pointer would cause pupillary constriction (Arch Ophthalmol, Nov 1999). She made an 11 year old girl to stare at an activated laser pointer for several multi-second exposures with the right eye. The victim immediately noted decreased vision. It took many months to recover her vision; long term effects of the injury are unknown.
Retinal injuries from lasers may be caused by ablative, thermal or photochemical mechanisms. These depend on power, wavelength, exposure time and size of the pupil (BMJ, 27 May 2010). Normally, the adverse impact may be transient; they may disturb the retina and the interconnecting layers and may induce clinical conditions causing loss of sight later.
Laser pointers costing a few dollars are available in curio shops, electronic stores or office supply shops. You may buy them directly or through mail order or by placing orders with internet outlets. Children may use them as toys.
Most laser pointers used while presenting lectures operate in the visible light region of wavelengths between 600 to 670 nanometre (one-thousandth of a millionth of a metre, nm). They are low powered, battery operated, hand-held devices and are cheaper than those operating at green light of wavelength 532 nm.
The response of the eye depends on wavelength with a peak at about 550nm. It decreases as either end of the spectrum is reached. If laser pointers are compared at the wave lengths of 670 nm, 635 nm and 532 nm at the same power level, the brightness as eye perceives it will be nearly in the ratios of 1:10:30.When the laser beam is closer to the eye’s peak response, it can produce adequate visual stimulus at lower power levels.
If you want to buy a laser pointer choose only one that is labelled Class II and operates with a wavelength between 630 nm and 680 nm. Maximum output should be less than 5 milliwatts.
Before you use a laser pointer, read the caution or danger sticker carefully. Never point the laser at another person. Do not point a laser pointer at mirror-like surfaces. A reflected beam can act like a direct beam on the eye. Never look directly at the laser beam. Never view a laser beam using a binoculars or a microscope.
Lastly, you must not gift a laser pointer to a child. You may regret later. Laser pointers are not toys.
The writer is Raja Ramanna Fellow, Department of Atomic Energy

No genetic effects in children of A-bomb survivors

2010-08-06T12:01:00.002+05:30

THE HINDU

S & T
Published: August 5, 2010 03:48 IST | Updated: August 5, 2010 03:58 IST August 5, 2010
No genetic effects in children of A-bomb survivors
K. S. PARTHASARATHY

AP SEVERAL STUDIES: In the 1950 Japanese national census nearly 2,80,000 persons claimed that they were exposed to radiation. Several studies have been carried out on the survivors. Photo: AP
On August 6, 1945, the U.S. dropped an atom bomb on Hiroshima. Nagasaki was bombed three days later.
In the 1950 Japanese national census nearly 280,000 persons claimed that they were exposed to radiation. Initially, the Atomic Bomb Casualty Commission and from 1975, Radiation Effects Research Foundation (RERF), carried out several studies on the survivors.
Research programmes
The research programmes covered Life Span Study (LSS), Adult Health Study, study of the Children of Atomic-bomb Survivors (F{-1}) and the evaluation of the lifetime health experience of a specially exposed population, namely those in utero at the time of the bombings.
Other areas covered included immunology, radiation biology, molecular epidemiology, cytogenetics, statistics and A-bomb dosimetry.
RERF researchers and other scientists studied the interaction with radiation and smoking.
Radiation increased the risk of lung cancer among the survivors. Among 105,404 subjects of the LSS, researchers identified 1803 primary lung cancer cases for the period 1958-1999.
They used individual smoking history information and the latest radiation dose estimates to investigate the combined effects of radiation and smoking on lung cancer rates.
Lung cancer risks
Relative to never-smokers, lung cancer risks increased with the amount and duration of smoking and decreased with time since quitting smoking at any level of radiation exposure (Radiation Research, 174, 2010).
The excess risk increased rapidly with smoking intensity up to about 10 cigarettes per day, but additive or sub-additive for heavy smokers smoking a pack or more per day, with little indication of any radiation-associated excess risk
The authors concluded that the joint effect of smoking and radiation on lung cancer in the LSS is dependent on smoking intensity and is best described by the generalized interaction model rather than a simple additive or multiplicative models
Fatty liver predicts ischemic heart disease or heart disease due to reduced blood supply to the heart.
Fatty liver predictors
The researchers at RERF observed the incidence and predictors of fatty liver by examining 1635 survivors of Nagasaki A-bomb every two years through 2007 (mean follow up for 11.6 y) by abdominal ultrasonography.
The subjects were without fatty liver at base line (November 1990 through 1992). The researchers diagnosed 323 new fatty liver cases.
The average incidence was 19.9 cases in 1000 person years peaking in the sixth decade of life (Hypertension Research April 2010).
After controlling for age, sex, and smoking and drinking habits, obesity, hypertriglyceridemia (large levels of tryglicerides) and hypertension were predictive of fatty liver.
All variables included
When all variables are included, obesity, hypertriglyceridemia and hypertension remained predictive.
Scientists have not observed genetic effects in the children of A-bomb survivors.
To evaluate the genetic effects of A-bomb radiation, RERF researchers examined mutations at specific loci in the chromosomes of exposed families (father-mother-offspring, mostly uni-parental exposures) and control families. The mutation rates observed were not statistically significant.
That radiation exposure causes thyroid cancer is an established fact.
But we do not know the radiation effects on papillary micro carcinoma (PMC) of the thyroid, a common sub-clinical thyroid malignancy.
RERF researchers identified PMCs in a subset of 7659 subjects after reviewing their pathology and evaluating the histological features of the tumors.
Papillary thyroid cancer
From 1958 to 1995, they detected 458 PMCs among 313 study subjects; most of them exhibited pathologic features of papillary thyroid cancers.
A significant radiation-dose response was found for the prevalence of PMCs with the excess risk observed primarily among women.
Exposure to low-to-moderate doses of ionizing radiation appears to increase the risk of thyroid PMCs, even when exposure occurs during adulthood (Cancer, 2010).
Raja Ramanna Fellow with the Department of Atomic Energy
(ksparth@yahoo.co.uk)
Keywords: Hiroshima bombing, genetic effects
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Interview with Dr Jack Valentin, Scientific Secretary, ICRP - AERB NEWSLETTER 2000 Vol 13, No 1

2010-06-13T16:09:00.002+05:30

Interview with Dr Jack Valentin, Scientific Secretary, ICRP - AERB NEWSLETTER 2000 Vol 13, No 1
www.aerb.gov.in/T/NewsLetters/2000/vol-1/newsltr6.html

Dr. K.S.Parthasarathy in conversation with Dr. Jack Valentin, Scientific Secretary, ICRP: Dr. Jack Valentin, Scientific Secretary, International Commission of Radiological Protection (ICRP), is a Ph.D in genetics. After various positions in research, teaching and forensic laboratory work, he was recruited to the Swedish Radiation Protection Institute (a licensing authority) in 1983 as one of its Deputy Directors. There, he was first responsible for non-nuclear activities, turning then in 1989 to nuclear energy supervision. In February 1997, he took up his current post as Scientific Secretary of ICRP He has authored about 100 publications and has held various commissions of trust within the area of radiation protection, including a current assignment as a member of the Executive Council of IRPA (the International Radiation Protection Association).
Secretary, AERB interviewed Dr. Valentin at Mumbai.

Dr. Valentin, Swedish scientists have contributed enormously to medical physics and radiological protection. I remember Prof.- William Spiers, the pioneering medical physicist from UK, used to proudly remember his association with Rolf Sievert. Whenever we discussed the early developments in the field of medical physics, Professor Spiers described the efforts in various countries. The Stockholm technique in the treatment of uterus cancer was always referred to as a major contribution. Professor Spiers used to pay glowing tributes to Prof. Sievert.

Dr. Valentin: Prof. Sievert was a disciplined scientist.

KSP: It is appropriate that the unit of some of the important radiation quantities is named after him. I was told that the pressurized ion chamber he designed and fabricated in early fifties responded to Chernobyl fall out in 1986. Originally this equipment was used to measure radioactivity in the human body.
Dr.Valentin: There was a network of instruments available all over the country to measure radiation levels. But at the time of Chernobyl, one had to call it to get the results. They were not continuously reporting. But now the situation is different. If measurements exceed certain trigger levels, staff on call are automatically alarmed.

KSP: I remember the pioneering contribution by Prof. Hultquist who measured radon levels in Swedish dwellings during late fifties. Measurement of radon levels to study its impact on the dose to man become fashionable and important in the late seventies in several countries. What was the inspiration for Prof. Huitquist to carry out those measurements?
Dr Valentin: Maybe for the fun of it. Some of the earlier papers were written very well. I recollect that there were newspaper clippings stating that the radon levels in some house is dangerous.
KSP: When the instruments were crude, those who handled them had special expertise. All the care is taken so that measurements made are reliable. Nowadays in view of the availability of computer guided instrumentation, the persons who handle them do not get the insight and understanding of the problems. Prof. Hultquist used very primitive instruments to make very reliable measurement of radon levels. Do you think that sophisticated instruments may come in the way of gaining insight about the true nature of physical phenomena?
Dr. Valentin: I can see your point, and it applies to other areas of science as well, but after all better equipment does permit better science. The important thing is to remember that the demand on brains remains at least as tough as, before, even f modern equipment simplifies some of the manual work.
KSP: I understand you are a geneticist by profession. How did you become a radiation protection specialist? How did you choose this area of specialty?
Dr.Valentin: After graduating in genetics at a department in the University of Stockholm which had interest in the effect of radiation on genes, I began teaching at the University of Gothenborg. Then I wanted to get back to Stockholm as my wife was there. At that point of time, a vacant post was advertised in Stockholm. They wanted a person with radiation protection experience. I applied and got the job. Actually, that, is the way I chose radiation protection for a career.
KSP: How long were you associated with the International Commission on Radiological Protection?
Dr. Valentin: I was elected to the International Commission on Radio- logical Protection in 1989. Before that also I was in contact with ICRP.
KSP: Historically, In 1 934, an exposure rate limit for ionizing radiation was recommended to ensure protection of persons. This corresponded to about 500 mSv/year. In 1950, the ICRP recommendations lowered the permissible exposure rate to 150 mSv/ year. Currently, ICRP recommends a dose limit of 100 mSv averaged over 5 years, in effect, 20 mSv/year. Yesterday's safe dose limit becomes unsafe today. How will you explain this to public?
Dr.Valentin: That is an interesting question. It is a major problem. In 1934 and 1950, the objective of radiation protection was still limited to protecting radiation workers from deterministic harm. It was not dealing with public safety. Protection of public was not envisaged.
KSP: The information available then was skin damage suffered by those who handled x-ray units carelessly.
Dr.Valentin: That is right. The atmospheric weapon testing during the fifties lead to increased awareness. In 1 956, a dose limit of 50mSv per year for workers was introduced. For the first time, a dose limit to public of 5mSv/year was recommended. These recommendations were aimed at protection against stochastic harm. These recommendations recognized the possibility of a linear, non-threshold dose-response relationship. They did not conclude that the doses should be reduced even below the dose limit.- In 1965, ICRP retained the 1956 dose limits, but stated that the doses ought to be reduced if this was readily achievable. In 1977, ICRP observed that the dose limits are not a means to keep doses low but these are values that should not be exceeded. The concept of optimization to keep doses as low as reasonably achievable was put forward.
KSP: The evolution of the philosophy of radiation protection is very interesting indeed. The specialist may fully appreciate the consistency and cogency of the concepts. But public may not follow these nuances. As a matter of fact, public is sensitized about the lowering of dose limits. They may be disturbed by the fact that yesterday's safe limit becomes unsafe today. How are we sure that today's safe limit will not be unsafe tomorrow? I used to draw the example of aircraft. Modern jet aircraft is safer than propeller driven aircraft. Notwithstanding this, propeller driven aircraft is still in use. As technology improved, better and safer airplanes were manufactured. Propeller- driven airplanes have their own limitations. Since they are still used, -they are accepted to be safe.
Dr.Valentin: I think that it is a good example. We have increased safety in every field Radiological protection is no exception. It is a fact that society demands more safety in every field of activity.
KSP: But public perception of radiation risk is admittedly disproportionate with any measurable harm. How can we help to improve public perception? Does ICRP add to the confusion?
Dr.Valentin: I agree, at times we add to the confusion! But it is not certainly intentional. I feel that it is better not to trivialise the risk but to evaluate the risk from the practice. There are so many practices. We have to judge them on merit. We accept large risk because of large benefit.
KSP: Recently, I saw a report that the Federal Legislation regarding radiation workers in a European country recommends a cytogenetic examination as a part of the routine medical check up. I also noticed a comment that this sounds like the ultimate job-creation scheme for unemployed cytogeneticists!! Do you have any views on the practices
Dr.Valentin: It is a waste of effort. It is better to spend resources differently.
KSP: The field of radiation protection is unique. Probably in no other field such exacting and very often expensive epidemiological studies of millions of people in dozens of investigations were carried out to establish harmful effect, if any, of an agent. For instance, the study of the survivors of the atomic bombings at Hiroshima and Nagasaki started in during late forties and continues to- date. The Radiation Effects Research Foundation (RERF) continues to publish their important findings.
Dr. Valentin: These are very important studies and must be continued.
KSP: Some of the newer lines of study in radiobiology emerged from. unexpected observations. For instance, let us take the example of what is currently called genomic instability.
Dr. Valentin: There are experimental results which appeared to be strange in some ways. They could not be explained according to conventional hypotheses.
KSP: The hypothesis that cells which were exposed to ionising radiation may transmit some chromosomal instability to daughter cells was exciting enough. I vividly remember the early studies of the irradiation of stem cells by alpha particles. The National Radiological Protection Board has asserted that the estimates of radiation- induced cancer risk in humans have been derived directly from epidemiological observations and are, therefore, independent of the otential contribution from any novel cellular mechanism. Do you think that genomic instability will have any impact on ICRP recommendations?
Dr. Valentin: At present, I find that unlikely, but it would seem wise to avoid being categorical. Genomic instability is an interesting phenomenon. We must investigate it thoroughly. ICRP is interested in all radiation related phenomena.
KSP: Currently the Commission believes that the standards of environmental control needed to protect man to the degree currently thought desirable will ensure that other species are not put at risk. How is it that ICRP made such an assumption? Is there any evidence?'
Dr.Valentin: This is a very timely question. ICRP plans to set up a Task Group to make sure that our next set of basic recommendations provides a rather more convincing section on protection of the natural environment. The present statement is not necessarily wrong, but at the very least it needs to be corroborated by proper references to pertinent research. The rare exceptions that we know of today should be mentioned and evaluated. Perhaps we should even change the vantage point - it may be more in line with regulation of other dangers to say, if possible, that proper protection of the environment will be sufficient to also protect man. We do not currently envisage any significant change to authorised release limits, but we need to argue and express this much more cogently.
KSP: DNA molecule may have some molecules of radioactive carbon or H3 associated with it. What will be the impact of radioactive decay and transmutation of the element to another element? ICRP is ignoring such events.

Dr.Valentin: I would not say that we are ignoring such events. As a matter of fact, we do not know what the effects are. There has been, similarly, the effects of Auger electrons. For want of adequate information, we are unable to comment on them.
KSP: Any comment on the on-going linear non-threshold controversy on dose response.
Dr.Valentin: LNT concept is simple and practical. Recent studies have shown that there is a statistically significant response at dose levels as low as 5OmSv. There is reasonably acceptable evidence that children x- rayed while they are in their mothers womb have increased incidence of leukemia. Certainly there are wide uncertainties in the response of any organism to low doses.
KSP: Professor Roger Clarke, the current Chairman of ICRP, has circulated a position paper proposing certain changes in the concept and philosophy of radiation protection. The new concepts may make the philosophy of radiation protection more acceptable and cogent. What is the current status of the paper? Any comments?
Dr.Valentin: Professor Clarke's proposal, and some other suggestions, will be discussed at the IRPA 10 Congress in Hiroshima in May 2000. Health physicists and other interested parties all over the world have been invited to comment, primarily through the IRPA meeting. In October 2000, ICRP will discuss the proposal and the comments received. Based on that, I assume that we will be able to devise terms of reference for a Task Group which will draft new recommendations. The Clarke proposal will have served marvelously to initiate discussions. Judging from the many comments already received, positive and negative, my personal guess would be that the end result includes many parts from the Clarke proposal and many other parts which are quite different.
KSP: What will be the direction in which the ICRP will proceed in the next ten years?
Dr.Valentin: You have certainly touched on two of the major things: New fundamental recommendations are to be expected around 2005, and protection of the natural environment will be addressed more ambitiously. The new recommendations will, as usual, require detailed guidance which will occupy us later in the ten-year period. Another aspect, which we haven't talked about, is that ICRP is keen to increase its transparency and make processes and persons involved known. Our ideal is to be well known, well understood and well respected not only among health physics experts but also by environmentalists, users of radiation, and any other persons interested in radiation and in protection against radiation harm.

India's innovative nuclear power reactor

2010-06-10T16:02:00.005+05:30

Date:10/06/2010 URL: http://www.thehindu.com/thehindu/seta/2010/06/10/stories/2010061050631600.htm
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India's innovative nuclear power reactor
The reactor's development is an effort to realise futuristic objectives through innovative configuration of present-day technologies
— Photo: K. Ramesh Babu

Advantages:The new reactor produces much less plutonium and helps in thorium utilisation.
People waiting for a nuclear renaissance expect that the new reactors on the drawing board should assure a very high level of safety and security; they must have the ability to perform with a lower level of technological infrastructure prevailing in several developing countries; they must have high fuel use efficiency and superior waste disposal options.
“The development of the Advanced Heavy Water Reactor, AHWR300-LEU, is an effort to realize these futuristic objectives through innovative configuration of present day technologies,” Anil Kakodkar and Ratan Sinha, the designers of India's innovative nuclear reactor wrote in the May 2010 issue of Nuclear Engineering International.
They called the reactor India's passive breeder.
“As a result of its fuel mix and fuel breeding properties, the 300 MWe plant requires 42 per cent less mined uranium per unit of energy produced than a modern high burn up PWR”, they added.
AHWR300-LEU with an estimated design life of 100 years is a vertical, pressure tube type, boiling light water-cooled, heavy water- moderated reactor with reduced environmental impact. It has many features which are likely to reduce both its capital and operating costs.
The designers have eliminated primary coolant pumps and drive motors and related control and power supply equipment, thereby saving the electric power to run them. This helps to reduce cost and to enhance reliability.
The use of heavy water at low pressure reduces the potential for leakages. The heat generated in the moderator will be recovered and used for heating the feed-water.
Quick replacement
The shop assembled-coolant channels have features which enable quick replacement of pressure tubes alone without affecting other components.
The design objective of the reactor is to require no exclusion zone beyond the plant boundary. The reactor will use natural circulation to remove heat from its core under operating and shut down conditions. In case the primary and the secondary shut down systems are not available due to the failure of all active systems or malicious employee action, passive injection of a “poison” — a high neutron absorbing liquid, in to the moderator will shut down the reactor.
When the reactor operates, its core will be very hot. Coolant removes the heat. If coolant is not available due to a Loss of Coolant Accident (LOCA), the emergency core cooling system (ECCS) will remove heat by passive means.
If the primary coolant tube ruptures, a large flow of water from accumulators will cool the reactor initially. Later, the core will be cooled by the injection of cold water from a 7000 cubic metre Gravity Driven Water Pool (GDWP) located at the top of the reactor building. After that, the passive containment cooling system (PCCS) provides long term containment cooling. GDWP serves as passive water sink giving a grace period of three days.
The reactor has a double containment with an elegant design which assists the formation of a passive water seal in the event of a loss of coolant accident. The seal isolates the reactor containment and the external environment, preventing the spread of radioactivity.
Fission of Uranium-233
The reactor fuel on an average contains 19.75 per cent of enriched uranium and the balance thorium oxide. A significant fraction of the reactor power, about 39 per cent, comes from the fission of Uranium-233 derived from in-situ conversion of thorium-232.
The reactor physics design has inherent safety characteristics during all conditions likely to be encountered during startup, shutdown and LOCA.
During an interview, Dr Sinha has stated that the scientists and engineers at BARC have designed a novel advanced heavy water reactor to burn thorium ( IEEE Spectrum, 2008)
“They say that because no reactor in the world today uses thorium on a large scale, they will be breaking new ground”, he added
Currently BARC has the facility for large scale validation work.
Partly as a result of this, the reactor can achieve commercial operation by 2020.Indian scientists have been exploring various fuel cycle options for improved versions of AHWR.
AHWR300-LEU has all the safety features of AHWR. It also helps in thorium utilization.
It produces much less plutonium and minor actinides compared to Pressurized Water Reactors(PWR) which is the mainstay internationally. In view of that, this reactor is more proliferation resistant.
Since minor actinides (which have relatively long half life) are less than those in PWR, it is a better choice from considerations of waste management.
AHWR300-LEU has better reactor physics characteristics.
K.S.PARTHASARATHY
Raja Ramanna Fellow, Department of Atomic Energy
( ksparth@yahoo.co.uk )
© Copyright 2000 - 2009 The Hindu

Radiation Incidents in Delhi: The Way Forward

2010-05-15T08:43:00.005+05:30

Radiation Incidents in Delhi: The Way Forward May 2, 2010 - 00:51

By Dr K S Parthasarthy
The unfortunate radiation incident in which several persons got exposed to radiation in Delhi highlights the need to enforce strictly the multilayer radiation monitoring system recommended by the Atomic Energy Regulatory Board (AERB).
This must be implemented at different stages of value addition of metal scrap.
In the Delhi incident, seven persons were admitted to hospitals for treatment. Scientists handling the emergency located and safely removed 11 radiation sources of various types. None of these are indigenously fabricated sources.
Over the past few years, AERB has been publicising measures to prevent such incidents. It arranged meetings, workshops and discussions in different regions in the country. As it happened in the USA, only those firms who faced adverse economic outcomes due to contaminated steel products cared to follow AERB’s suggestions. If everyone bought and used the relatively inexpensive radiation monitoring equipment, which AERB recommended, the incident would have been prevented.
AERB was concerned about the incidents in which steel got contaminated with Co-60. It took such events as wake up calls. The Board interacted with the Engineering Export Promotion Council (EEPC), Chambers of Commerce and Industry (CII) and All India Induction Furnaces Association and licenses of industrial gamma radiography institutions and unfolded its plan of action.
The multilayer radiation check system recommended by AERB includes various elements introduction of procedure that every importer of metal scrap should obtain a certificate from the exporting country that the scrap is free from radioactivity; Inclusion of a clause in the purchase specification that the material shall be free from radioactivity; establishment of independent check/test system for radioactivity in the incoming and outgoing material, if any radioactivity detected, segregation of material at least 10 m away from the occupied areas and information to AERB immediately; selling /supplying the material with a self certificate that the material is free from radioactivity.
Other measures included radiation monitoring of the metal scrap after the import and prior to melting the scrap; radiation monitoring by steel mills prior to rolling of steel ingots into the desired shape; radiation monitoring by manufacturers and exporters of SS products prior to manufacture/export of products and inclusion of radioactive contamination check in the check list of QA program prior to export or supply of the material.
AERB wanted all concerned agencies in steel metal recycling industry such as metal scrap dealers, steel foundry owners, steel rolling mills and manufacturers of steel products, small or big to scan the metal for the presence of radioactivity with the help of radiation sensing devices prior to using the metal for value addition. If radiation is detected in any material, AERB shall be notified so that appropriate control can be instituted over the contaminated material.
AERB informed various stakeholders that radiation sensing devices, which can detect and measure just above the natural background radiation level (5-10 microR/h), can be procured indigenously imported.
The associations of scrap dealers must arrange radiation safety awareness programs related to the detection of radiation in the steel melting industry. AERB proposed that they may develop a facility with trained man power and equipment to provide service of radiation monitoring for the needed industry; and coordinate with AERB for disposal of the identified contaminated material and related matters. In spite of the vigorous measures, it is obvious that AERB’s suggestions have not percolated down to every stake holder in this lucrative business.
Scientists from the Bhabha Atomic Research Centre have developed inestimable expertise in tracing lost sources. They have been training various dedicated groups for several years in handling radiation emergencies. This priceless contribution became very useful in the hour of need. The Department of Atomic Energy is making available a few radiation monitors to the association of scrap dealers, so that they can monitor the presence, if any, of radiation sources in the scrap material they gather. If they find any, they can notify the concerned authorities for further follow up.
An important element in the defence in depth arrangement to prevent radiation incidents due to imported sources is the installation of portal monitors at ports and airports through which scrap material in bulk may enter the country. Scientists from BARC have surveyed various locations and identified places for installing them.
The unfortunate event at Delhi may accelerate the process. Admittedly, the project involves the coordination of various agencies. Installing the monitors with the assistance of specialists and making foolproof arrangements to maintain them 24X7, is a complex activity. It can be and has to be carried out with the support and coordination of every one.
Prompt medical assistance is an important element in handling patients exposed to radiation. The patient may approach general practitioners. They may think that the injury is due to reasons such as insect bite. Radiation injury has no special signs or symptoms (IAEA/WHO, 2000). Few physicians have adequate knowledge to identify them.
Recognising this fact, AERB published “A Handbook for the Medical Management of Persons Exposed in Radiation Accidents” in 1989 and a detailed guide in 1990. The guide received critical reviews from H Jammet, Jeane Claude Nenot and other internationally acclaimed specialists.
AERB published a poster highlighting the course to be followed while treating the patients. In 2000, WHO/IAEA realised that in most cases, physicians will not be able to identify the reasons for symptoms suffered by radiation exposed persons. They published a leaflet titled “How to recognise and initially respond to an accidental injury” at http://w.w.w.who.int/ionizing_radiation/a_c/IAEA WHO Leaflet-Eng%20blue.pdf.
The leaflet recommends the following books by IAEA/WHO for further reading: Diagnosis and Treatment of Radiation Injuries. Safety Report Series, No 2, IAEA, Vienna, 1998: Planning the Medical Response to Radiological Accidents. Safety Report Series, No 4, IAEA, Vienna, 1998; Health Surveillance of Persons Occupationally Exposed to Ionizing Radiation. Safety Report Series, No 5, IAEA, Vienna, 1998. These documents are available for free download.
The unfortunate incident at Delhi may act as the final wakeup call for establishing the way forward to handle such potential emergencies. (PTI Feature)

Lessons to be learnt from Delhi radiation incident

2010-04-17T11:20:00.002+05:30

Date:15/04/2010 URL: http://www.thehindu.com/thehindu/seta/2010/04/15/stories/2010041551311400.htm
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Lessons to be learnt from Delhi radiation incident
Photo: K. PIchumani

The source: Virtually all instances of steel contamination seem to have been caused by radioactive sources which came with imported scrap. —
At 12:45 hrs on April 7, 2010 the Atomic Energy Regulatory Board (AERB) received a fax message from Indraprastha Apollo Hospital, Delhi stating that a scrap metal dealer admitted to the hospital showed symptoms suspected to be caused by radiation exposure.
Six more workers who also exhibited similar symptoms were admitted elsewhere. On receiving the information, two AERB officers who were already in Delhi inspected the shop and its surroundings, identified high radiation levels and promptly shielded some suspected high radiation locations with metal sheets to reduce the radiation levels.
As per the procedure in place, a team of scientists from Bhabha Atomic Research Centre (BARC)and the Narora Atomic Power Station , mobilized by the Crisis Management Group of the Department of Atomic Energy (DAE) and scientists from AERB visited the site again and restored normalcy by safely removing the sources into appropriately shielded containers. By April 9, 2010, the radiation levels at the site became normal background radiation levels.
“It was indeed a difficult operation; we collected cobalt-60 sources of high strengths in the form of wires under trying circumstances and secured them in special containers. We instituted strict dose control procedures which ensured that the radiation doses to us were within limits,” said Dr. K.S.Pradeep Kumar, Senior Scientist and Head, Emergency Response System and Methods Section.
“We learnt a few lessons. The team from Narora brought many tools and accessories; their support proved to be very crucial,” he clarified. He paid compliments to the excellent cooperation extended by the Delhi police.
A handful of radiation incidents in which persons got exposed to very high radiation doses occurred in India. Most of the cases were because of gross violation of safety procedures in handling industrial gamma radiography sources.
In the most serious case, a railway gang man received high dose as he kept gamma source in his pocket for a few hours. The source was lost in transit because of negligence of radiation workers in a company. Follow up action led to the winding up of the company.
The victim pocketed the shining object assuming that it is valuable. He was admitted into BARC Hospital initially for three months and was followed up for one and a half years. He survived after several skin drafts and other procedures.
The Delhi incident was a serious one. That such incidents were rare would be poor consolation for those seven persons who were exposed to radiation. There must be zero tolerance to such events.
AERB had suggested several preventive measures ( The Hindu, Nov 13, 2008). In the light of a few steel contamination incidents, AERB proposed to put in place a multi layered radiation check system ( The Hindu, February 26, 2009). These need closer review, strengthening and more effective enforcement.
Many scrap dealers have bought radiation monitors. The proposal to erect radiation monitors at major ports is yet to be implemented. Since virtually all instances of steel contamination seem to have been caused by radioactive sources which came along with imported scrap, radiation monitors must be installed urgently at all ports. The radiation incident at Delhi must be considered as the final wake up call. There are plans to equip selected police stations in major cities with radiation monitors. The task is humongous but achievable through dedicated efforts.
Radiation exposure from “orphan sources” was a topic of discussion in many meetings held by the International Atomic Energy Agency (IAEA) since 1998.An initial review indicated that, more than 110 countries may not have minimum infrastructure to properly control radiation sources (IAEA, 1999).
Since 1990, 300 radioactive sources were recovered from Georgia. There were instances in which intense radiation sources used in agricultural research such as mutation studies were found abandoned in trucks
In the United States alone, the Nuclear Regulatory Commission (NRC) annually receives about 200 reports of lost, stolen or abandoned radioactive sources. This is disconcerting as U.S. has a stringent regulatory system. AERB receives less number of reports annually, presumably because we have far less number of sources in use. Also as in U.S., AERB has a very effective system to track high intensity sources.
K.S. PARTHASARATHY
FORMER SECRETARY, AERB
ksparth@yahoo.co.uk
© Copyright 2000 - 2009 The Hindu

Radiation dose reduction in medical imaging needed

2010-02-18T09:56:00.009+05:30

Of late there has been renewed interest in reducing radiation doses from medical imaging procedures.This has been partly due to extensive media coverage of a few over exposure incidents

K.S.Parthasarathy

Date:18/02/2010 URL: http://www.thehindu.com/thehindu/seta/2010/02/18/stories/2010021850111500.htm Back Sci Tech

Radiation dose reduction in medical imaging needed

CT scans involve extended exposure to radiation, and hence higher radiation dose

— Photo: K. R. Deepak

Overdose: The adult effective dose from a CT exam of the head is equivalent to the adult effective dose from roughly 100 chest X-rays.

On February 9, 2010, the US Food and Drug Administration (FDA) published a white paper titled “Initiative to reduce unnecessary radiation exposure in medical imaging.” FDA found out several instances of radiation over exposures; some of them were as appalling as the ones reported within a few months of the discovery of X rays!

The new FDA initiative promotes safe use of medical imaging devices, supports informed clinical decision making and offers measures to increase patient awareness.

On October 8, 2009, FDA issued a radiation alert when it discovered that 206 patients who underwent CT perfusion studies in a hospital may have received 6 to 8 times more dose than what is necessary.
Media coverage

Some patients suffered hair loss and reddening of the skin indicating high radiation doses. The Agency found out that the overexposures were more wide-spread. Media covered these excesses extensively.

In January 2008, 23 month old Jacoby Roth fell out of bed; his doctor ordered a CT scan to find out damage, if any, to his spine.

A technologist carried out 151 scans in 68 minutes. Within a few hours, the child developed a bright red ring around his head from the massive overdose of radiation (AuntMinnie.com, 2009).

The dose to the child may have been about 2800 mSv to 11,000mSv. (mSv is a unit of radiation dose, the dose in a normal paediatric study of the entire spine may be about 1.5 to 4 mSv). The California Department of Public Health (CDPH) imposed a fine of $25,000 on the hospital. The technologist is fighting to retain her licence. Parents are suing the hospital.

Clinically indicated computed tomography (CT), nuclear medicine procedures and fluoroscopy carry immense benefits for patients when they are executed by trained professionals using optimally adjusted equipment. Misadministrations are rare.
The assertion

FDA asserted that there must be appropriate justification for ordering and performing each procedure, and careful optimization of the radiation dose used. International Commission on Radiological Protection (ICRP) upholds these basic principles.

“Because CT, fluoroscopy, and nuclear medicine procedures involve repeated or extended exposure to radiation, these types of exams are associated with a higher radiation dose than projection radiography.

For example, the adult effective dose from a CT exam of the head is equivalent to the adult effective dose from roughly 100 chest X-rays. The adult effective dose from a CT exam of the abdomen is roughly equivalent to the adult effective dose from roughly 400 chest X-rays”, the FDA paper cautioned.

FDA may require that CT and fluoroscopic devices display, record, and report radiation dose and alert users when the dose exceeds a diagnostic reference level, a peak skin-dose threshold for injury, or some other established value.

The Atomic Energy (Radiation Protection) Rules, 2004 (RPR2004) require that the licensee “shall for optimising the medical exposure ensure that performance of the equipment is verified periodically by appropriate quality assurance tests.”

The licensee shall also “ensure that any accidental medical exposure is investigated and a written report submitted to the competent authority.” The Atomic Energy Regulatory Board (AERB) has not so far received any report of accidental exposures in medical imaging, though there is anecdotal evidence of their occurrence.

RPR 2004 requires that the licensee shall maintain the records of radiation doses received by therapy patients and activities administered to patients in diagnostic and therapeutic nuclear medicine procedures. The rules need amendment to make recording of diagnostic X-ray dose mandatory in line with recent trends.

Inputs from an AERB funded safety research project indicate that at least 1.5 lakhs of children are found to be receiving excess radiation exposure because some of the CT Centres do not follow paediatric protocols. Parents should insist that the physicians should refer their children to only centres which follow appropriate protocols.

AERB’s effort to enforce strict compliance of rules in an area which grew unbridled for the past several decades is a daunting task.

ksparth@yahoo.co.uk

(The author is Raja Ramanna Fellow, Department of Atomic Energy)

K.S. PARTHASARATHY

© Copyright 2000 - 2009 The Hindu

Is work in a nuclear power plant risky?

2010-02-12T06:29:00.004+05:30

The Tribune

SCIENCE & TECHNOLOGY Friday, February 12, 2010, Chandigarh, India

Is work in a nuclear power plant risky?
K S Parthasarathy
A 24 year old who is about to join the Department of Atomic Energy (DAE) as a scientific officer, is troubled by what he saw on a TV channel. He is unmarried; his parents are worried about the alleged damage to DNA by radiation. I assured him that there is no such harm. TV channels often go overboard and make unsubstantiated claims.
A 63 year old person asked me whether the throat malignancy, which, his 33 year old daughter is suffering from, is likely due to the possible radiation exposure he might have received while working in a nuclear power plant when he was 28 year old.
Thyroid diseases are not infrequent. No one knows for sure the reason for getting it. But there is no evidence that radiation exposure to father may lead to cancer in their children.
Workers in nuclear power plants will receive some radiation dose. Nuclear Power Corporation of India Limited (NPCIL) has instituted strict procedures to keep the doses to workers within the limits prescribed by the Atomic Energy Regulatory Board (AERB) and to values As Low As Reasonably Achievable (ALARA). Their radiation risk is insignificant.
ALARA committees with Chief Superintendents as chairmen, section heads as members and health physicists as member secretary review radiation work at each station periodically. Sectional ALARA committees plan work involving radiation exposures.
Each Station prepares a work plan, identifies various activities involving radiation exposure and gets AERB's approval for an annual “Radiation Budget”. If any Station exceeds the budget, AERB will not be amused!
The interior areas of the plant buildings are categorised into four zones for radiation and contamination control. Healthphysicists record radiation levels and airborne activity with prescribed frequency. Movement of every worker within the zones is controlled. Before entering Zone 2, 3 &4, they must wear lab coat, gloves and shoe covers and personnel dosimeters. They come out through sensitive portal monitors which will detect contamination, if any, present. They check hands and shoes using special monitors.
Annual reports published at (www.aerb.gov.in) indicate that the compliance with its stipulations is near total. For instance, during 2001 to 2008, among the annual average workforce of about 14,000 workers, one worker each in Rajasthan Atomic Power Station (RAPS) and Narora Atomic Power Station (NAPS) exceeded the limit in 2001; in 2002, one worker each in Madras Atomic PowerStation (MAPS) and NAPS; in 2007, two workers in NAPS exceeded the limits. This is indeed a creditable record.
Dose limits are based on conservative assumptions. It is inconsequential if any one receives, occasionally, a dose above the limit.
The Station managements made improvements in ventilation, reduced heavy water leakages, shielded hotspots, filtered crud from heat transport system, promptly detected and removed failed fuel bundles and used cobalt-free materials (Radiation from Cobalt-60, formed by actrivation of cobalt present in certain reactor components increases the radiation field). Many elegant engineering solutions helped to reduce radiation doses to workers.
Radiation protection standards assume that any dose of radiation, no matter how small, involves a possible risk to human health (World Nuclear Association, November 2009). After reviewing 200 peer-reviewed publications, Electric Power Research Institute (EPRI) concluded that this methodology may have been over-estimating the risks. (World Nuclear News, December 2).
Radiation protection standards are based on studies by scholarly bodies such as the US National Academy of Sciences (NAS)’ Biological Effects of Ionizing Radiation Committee, the International Agency for Research on Cancer (IARC) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). They indicate that at low doses, radiation risks, if there are any, are very small. Negligibly small risks are no risks at all. Work in a nuclear power plant is not a risky occupation.
The writer is Raja Ramanna Fellow, Department of Atomic Energy

Many glaciers, ice caps worldwide in retreat

2010-02-12T05:43:00.003+05:30

Date:04/02/2010 URL: http://www.thehindu.com/thehindu/seta/2010/02/04/stories/2010020450051400.htm Back Sci Tech

Many glaciers, ice caps worldwide in retreat

90 per cent of the 612 glaciers across the High Asian region were retreating; this increased to 95 per cent from 1990 to 2005

— Photo: AFP

Core evidence: Ice cores collected in 2006 from the 6050 metre high Naimona’nyi Glacier lack the distinctive nuclear fallout footprints suggesting no net accumulation of ice since at least 1950s. This file picture shows the Khumbu Glacier in the Everest-Khumbu region.

Ice cores drilled from glaciers around the world generally contain elevated levels of beta radioactivity including chlorine-36 and tritium associated with thermonuclear bomb testing in the 1950s and 1960s (Kehrwald, Thompson and others, Geophysical Research Letters, Nov 22, 2008). These researchers found that the ice cores collected in 2006 from the 6050 metre high Naimona’nyi Glacier, in the Himalayas (Tibet), lack the distinctive nuclear fallout footprints suggesting no net accumulation of ice since at least 1950s .

Surprisingly, no one referred to these studies in the recent controversy over the Statement of the Intergovernmental Panel on Climate Change (IPCC) on the Himalayan Glaciers.

Professor Lonnie Thompson a leading glaciologist and a co-author of the paper made similar observations many months earlier (“Missing footprints of A-bomb fallout in Himalayan ice fields,” The Hindu, January 31, 2008).

Responding to my e-mail query, Prof. Thompson wrote that he conducted his research on glaciers across the Tibetan Plateau and on the Tibetan side of the Himalayas.

“From the Qilian Mountains on the northeast side of the Plateau, to the Kunlun Mountains in the west, to the northern slopes of the central and western Himalayas, all the glaciers and ice caps that I have studied are retreating,” he asserted.

He pointed out that all the glaciers he has studied in the Peruvian Andes are also shrinking. The glaciologists at the Institute of Tibetan Plateau Research in Beijing have found that from 1980 to 1990, 90 per cent of the 612 glaciers across the High Asian region were retreating, and from 1990 to 2005, this increased to 95 per cent.

Thompson admitted that meteorological records from the Tibetan Plateau and the Himalayas are scarce and of relatively short duration, most beginning in the mid-1950s to early 1960s; however those that do exist show that surface temperatures are rising, and rising faster at higher elevations than at lower elevations.

According to him, the Tibetan Plateau has been warming at a rate of 0.16 degrees centigrade per decade, with winter temperatures rising 0.32 degrees centigrade per decade.
GRACE data

“A recent paper by Matsuo and Heki in Earth and Planetary Science Letters (time-variable ice loss in Asian high mountains from satellite gravimetry) shows that from 2003 to 2009 the average ice loss from the Asian high ice fields, as measured by GRACE satellite observations, had accelerated twice as fast as the rate over four decades before, but the loss was not consistent over space and time”, he cautioned

He observed that ice retreat in the Himalayas slowed slightly, while loss in the mountains to the northwest increased markedly.

“So, between the surface temperature measurements, the satellite studies, the ground studies on glaciers, and ice core results, a case can be made that glacier retreat at high elevations is indeed occurring concomitantly with increasing temperatures, which is consistent with the IPCC model results which show not only low-latitude warming but an amplification of that warming at higher elevations where these glaciers are located,” he argued

Thompson stated that the rate at which glaciers respond to climate change depends on their size; larger a glacier, the longer it takes to retreat in response to a warmer/drier climate, or grow in response to a cooler/wetter climate.

“Thus, among the 15,000 glaciers in the Himalayas, the largest are currently reacting to changes that happened 100 years ago. However, some of the growing glaciers are in fact surging; that is, they are advancing because of dynamics of ice flow and not because of climate.
Temporal differences

On the short term, glaciers show rapid changes in response to changes in snowfall amounts as well as temperature, but over the long term temperature will dominate,” he clarified.

Prof. Thompson referred to their latest paper titled ‘Glacier loss on Kilimanjaro continues Unabated’ in the Proceedings of the National Academy of Sciences (November 2, 2009) which demonstrates that ice loss on Kilimanjaro is unfortunately right on track as predicted in their 2002 Science paper. New measurements completed on GEOEYE satellite images from July 17, 2009 shows that the loss of ice continues right along the project from their Science paper.

According to Anna Barnet, assistant editor and copy editor of Nature Reports Climate Change (July 9, 2009), Thompson has spent more time above 20,000 ft than any other human being. She noted that by collecting a vast library of ice samples from mountain peaks, he has developed a unique view of past and present-day climate change. Thompson had 7,000 metres of glacial ice in his collection (PNAS, 2006). He is eminently qualified to comment on the topic.

Prof. Thompson noted that the recent document by V.K. Raina, formerly Deputy Director General of the Geological Survey of India, has been catapulted into the fray over the Himalayan glacier retreat.

According to Prof. Thompson Mr. Raina states quite correctly in his report (before going on to present case studies of only 3 glaciers) that “a few glaciers cannot be taken as the representative of around 10,000 glaciers of various sizes that exist in the Indian part of the Himalayas.”

Prof. Thompson clarified that very few solid peer-reviewed papers exist on glacier retreat in this region of the world, and as Mr. Raina would evidently agree, nothing conclusive can be claimed based on studies of a handful of glaciers out of over 15,000 throughout the Himalayas, both on the Indian and the Tibet sides.

Poster child glaciers

Prof. Thompson stated that participants on both sides of the issue are drawing conclusions about what is happening in a very large and climatologically and topographically complex region based on the “behaviour” of a few glaciers that have been adopted collectively as the “poster child” for all the world’s bodies of ice.

He conceded that most glaciologists and climatologists, he included, do not believe that most of the Himalayas will be ice-free by as early as 2035.

‘The provenance of this statistic may not be scientific or peer-reviewed, and the authors and reviewers … may have erred by allowing it to slip past the fact-checking process while the report was being prepared, but it doesn’t invalidate the entire IPCC report.

If any of the report’s authors felt compelled for whatever reason to include such material, as apparently admitted by Murari Lal, one of the lead coordinating authors of the 2007 IPCC report’s chapter on Asia (US News and World Report, Jan 25), then that should be investigated and the current guidelines should be strengthened and more rigorously enforced to prevent future occurrences of non-peer reviewed material slipping through,” he suggested.

“Scientists hold the peer-review process as the “gold-standard” for publication, but as in all human endeavors mistakes are occasionally made.

“In the end, it is the total body of substantiated evidence on global climate change that is important, not occasional errors or miscommunications that provoke unbalanced and hyperbolic reactions,” Prof. Thompson clarified.

K.S. PARTHASARATHY

Raja Ramanna Fellow, Department of Atomic Energy

( ksparth@yahoo.co.uk )

© Copyright 2000 - 2009 The Hindu

My articles: Radiation: cancer risk estimates remain same

2009-12-18T05:29:00.000+05:30

My articles: Radiation: cancer risk estimates remain same

Radiation: cancer risk estimates remain same

2009-12-18T05:14:00.005+05:30

The complete report (UNSCEAR 2006) with all Annexes from the United Nations Scientific Committee on the Effects of Atomic Radiation has now been published the first set of Annexes in 2008 and the next set in 2009. Because of resource crunch, UNSCEAR could not publish the report which was ready in 2006. That the Committee did not have funds to publish its report promptly is regrettable. UNSCEAR reports underpin international standards for radiation protection.

Dr K.S.Parthasarathy

Date:17/12/2009 URL: http://www.thehindu.com/thehindu/seta/2009/12/17/stories/2009121750111300.htm
________________________________________
Back Sci Tech

Radiation: cancer risk estimates remain same
Radiation protection specialists can breathe easy due to the overall view of the U.N. Committee on current risk estimates
The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) in its latest report has reiterated that the current risk estimates for cancer and hereditary effects in humans from irradiation need not be changed, in spite of new findings about non-targeted and delayed cellular effects.
Latest annexures
The October 2009 issue of the Health Physics Journal has summarised the latest annexures which covered “Non targeted and delayed effects of exposure to ionizing radiation,” “Effects of ionizing radiation on the immune system”, and “Source to effects assessment for radon in homes and work places”. UNSCEAR published two other earlier annexures in August 2008.
“Non-targeted and delayed effects occur in cells that were themselves not irradiated. They include genomic changes in the daughters of irradiated cells, changes in non-irradiated cells as a result of signals from irradiated cells (so-called bystander effects), and potential health effects in offspring due to irradiation of the parents,” the Committee clarified in a press release.
Scientists have observed “genomic instability” (effect appearing later in cells formed after several multiplications) and “bystander effects” (effects that manifest in cells not directly affected).
These could not be explained by conventional hypotheses. The International Commission on Radiological Protection (ICRP) did not consider them while estimating radiation risk estimates.
In 2000, I sought the views of Dr Jack Valentin, the Scientific Secretary, ICRP, on the impact of genomic instability on ICRP recommendations.
The argument
The then National Radiological Protection Board (NRPB), U.K., has argued that the estimates of radiation induced cancer risk in humans have been derived directly from epidemiological observations, and are, therefore, independent of the potential contribution from any novel cellular mechanism (Interview in AERB Newsletter 13: 1, 2000)
“At present, I find that unlikely, but it would seem wise to avoid being categorical,” he cautioned. “We must investigate it thoroughly,” he asserted.
UNSCEAR 2006 seems to have settled the issue.
Norman Gentner, Chairman of UNSCEAR conceded that these non-targeted effects may potentially amplify the biological effectiveness of a given radiation dose by increasing the number of cells that experience effects over those directly exposed to the radiation (UNSCEAR Release, 2009)
UNSCEAR noted that any clear relationship between non-targeted effects and observed health effects attributable to radiation remains contentious.
“Risk estimates are based on population health studies, which implicitly incorporate all elements including direct targeted effects of irradiation as well as non-targeted and delayed effects,” the latest UNSCEAR statement, is almost similar to NRPB’s, made nine years ago.
Radiation protection specialists and regulators can breathe easy; the overall view of the Committee is that the currently available risk estimates do not require changes.
UNSCEAR 2006 noted that some recent studies have shown that low levels of radiation can stimulate the immune system, at least for short periods.
Experimental studies
These findings emerge from experimental studies and large scale epidemiological assessments of A-bomb survivors, residents of areas in Russia and the U.S. contaminated by weapons production, Chernobyl emergency workers and residents and patients undergoing radiotherapy. Data from these groups showed common patterns (UNSCEAR release, 2009).
The impact of ionizing radiation may be stronger during foetal development and in some diseases such as HIV AIDS; autoimmune diseases and genetic disorders also compromise the immune system making it more sensitive to irradiation.
The disclosure
UNSCEAR disclosed that there is direct evidence to confirm a small but detectable risk of lung cancer from living with radon in home.
The Committee evaluated recent direct studies of the public in Europe, North America and China exposed to relatively low levels of radon in their dwellings.
Thus far, researchers estimated the risk from radon from health studies of underground miners who were exposed to high levels of radon and its decay products.
United Nations set up UNSCEAR in 1955; its mandate is to report on levels and effects of radiation to the UN General Assembly. Resource crunch delayed the publication of UNSCEAR 2006. It has hopefully been corrected. The work of the Committee is crucial as it underpins international standards for radiation protection.
Raja Ramanna Fellow, Department of Atomic Energy
( ksparth@yahoo.co.uk )
K.S. PARTHASARATHY
© Copyright 2000 - 2009 The Hindu

Kaiga incident serves as a wake-up call

2009-12-04T06:41:00.006+05:30

Date:03/12/2009 URL: http://www.thehindu.com/thehindu/seta/2009/12/03/stories/2009120350081300.htm
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Kaiga incident serves as a wake-up call
Tritium is the least toxic of all radioactive materials, not posing any external hazard but internal hazard if ingested

Treating ingestion: Tritium can be removed faster by drinking more fluids and water. Administering diuretics to the workers is another effective method.

Recently, a bizarre incident at the Kaiga Generating Station received wide media attention. Someone deliberately added some tritiated heavy water into a water cooler at the Kaiga Generating Station causing radiation exposure to 55 workers who drank water from it.
Authorities have characterised it as “sabotage,” “act of mischief,” “malevolent act” etc. Specialists in the appropriate discipline will identify the right term to be used!
Very serious incident
It is a very serious incident. It adds a new dimension to the already existing security and access control procedures. Some procedures need tightening. It is a wake up call.
Media reports reflected heightened perception, concerns and some misunderstanding about the way the Station handled the incident.
Extracts of the reports and the related facts are listed thus:
“Tritium is very difficult to remove from the body.” It is not true. Tritium is another form of hydrogen; like ordinary hydrogen it reacts with oxygen and forms tritiated water. Ninety seven per cent of tritium entering the body remains in soft tissue, will reach equilibrium in 2 hours and will get removed with a typical half period of 6 days, through urine and perspiration.
Three per cent remains for a longer period (about 40 days). The two components are considered in calculating the radiation dose. Tritium’s physical half life of 12.3 years is not relevant.
We can remove tritium faster by drinking more fluids and water. Administering diuretics to the workers is another effective method (diuretics are drugs that help to remove water from body). This has to be done under medical supervision.
Effective dose control
That is why the workers whose intakes exceeded certain limits were sent to the hospital (Such interventions are done for effective dose control over the monitoring period). They were not admitted. They did not fall sick as reported by some newspapers.
Is tritium, a highly radioactive substance? Tritium emits beta particles of very low energy. It does not pose any external radiation hazard; it poses internal hazard if ingested. Tritium is the least toxic of all radioactive materials. But we must control all tritium intakes.
“How is it likely to impact the employees who drank the water?” “Doctors say that even the smallest exposure to radiation will have a long term health impact.”
The impact depends on the dose received by the workers. In the present case, only two workers marginally exceeded the radiation dose limit of 30 mSv prescribed by the Atomic Energy Regulatory Board.
No worker had received contamination from any radionuclide other than tritium.
Even the currently estimated doses will be reduced further as these workers take diurectics under medical guidance. When radiation doses are within, close to or below the limit, the health impact is insignificant. However, the doses to workers must be as low as reasonably achievable. Getting doses close to the limit repeatedly is not acceptable. In such instances the work practices must be evaluated to reduce the dose further.
What happens to people living along the Kali River? Especially downstream, who spend a substantial amount of time standing in water to catch fish and eat it?
The contamination was confined to a single water cooler. Specialists located and isolated it from use. The contamination incident has no environmental impact.
The Annual report of AERB (available at www.aerb.gov.in) gives the data on radioactive releases from all power stations.
The resultant radiation doses are small fractions of the AERB limit and are within the variations in the natural background radiation present everywhere. The Kaiga Generating Station is no exception.
Are there legal provisions against such malevolent acts? Rule 23 of the Atomic Energy (Radiation Protection) Rules, 2004, issued under Section 17 of the Atomic Energy Act 1962 states that “Every worker shall observe the safety requirements and follow safety procedures and instructions and shall refrain from any wilful act that could be detrimental to self, co-workers, the radiation installation and public.”
The penalties
Violation of rules made under Section 17 of the Act shall be punishable with imprisonment for a term which may extend to five years, or with fine, or with both.
Depending on the circumstances, if proved guilty, the accused may be convicted for violating the provisions under Section 10 of The Weapons of Mass Destruction and their Delivery Systems (Prohibition of Unlawful Activities) Act, 2005.
K.S. PARTHASARATHY
Former Secretary, AERB
( ksparth@yahoo.co.uk )

Dr K.S.Parthasarathy in conversation with Mr.Yuri Vishnevskiy

2009-11-15T13:40:00.003+05:30

Dr. K S Parthasarathy, Secretary, Atomic Energy Regulatory Board Interviewed Yuri Vishnevskiy, the then Chairman of Federal Nuclear and Radiation Safety authority of Russia (RF Gosatomnadzor) at Vienna during May 3-7, 1999. Extracts were published in AERB Newsletter
[Reproduced from AERB Newsletter Vol 12, No2, 1999]
[ Mr. Yuri Vishnevskiy is currently the Chairman of Federal Nuclear and Radiation Safety authority of Russia (RF Gosatomnadzor). He graduated from the Tomsk Polytechnic Institute in 1966 and worked in different official capacities (Engineer, Senior Engineer, Deputy Shift Head, Shift Head and Senior Shift Head) of the Syberia Chemical Plant from 1966 to 1988. He was Head of RF Gosatomnadzor Inspection at Balakovo Nuclear Power Plant from 1985-1991. In 1990 he was elected a People's Deputy of the Russian Federation. Mr. Vishnevskiy was appointed Chairman of Federal Nuclear and Radiation Safety Authority of Russia in 1991.
Dr. K.S. Parthasarathy, Secretary, AERB interviewed Mr.Yuri G. Vishnevskiy, Chairman, Gosatomnazdor of Russia. (Gosatomnadzor is the State Safety Regulatory Authority of Russia) at Vienna].
Excerpts:
KSP: Mr Vishnevskiy, I consider it a proud privilege and honour to talk to you on behalf of the readers of AERB Newsletter on the functions and the activities of the State Safety Regulatory Authority in Russia. Your enthusiastic participation at the Peer Review Discussion on 'Assessment of Regulatory Effectiveness' at the International Atomic Energy Agency gave me ample opportunity to observe you closely. Your interventions on several occasions assisted us to focus on key issues in nuclear regulation. Which are the areas of responsibility of Gosatomnadzor?

Mr.Vishnevskiy: Gosatomnadzor was set up in 1991 by a Decree of the President of the Russian Federation. It is the legal successor to Gosatomnadzor of the USSR. It is a federal executive body with responsibility for the state regulation of safety in relation to the use of atomic energy (except for regulation of activities connected with the development, production, testing, maintenance, storage, and decommissioning of nuclear weapons and also with the development, production and maintenance of military nuclear power installations. The aim of the agency is to establish a situation where the staff of the nuclear facilities, the population at large and the environment are protected from undue radiation risks and where uncontrolled distribution of nuclear material is excluded.

KSP: So the Gosatomnadzor has a wide spectrum of responsibilities.

We issue licenses to various users of atomic energy after ensuring that safety requirements are met. My agency organises and implements the superiision of the production and use of atomic energy, of handling of nuclear materials, radioactive substances and radioactive waste. We carry out the supervision for non-proliferation of nuclear technology and nuclear materials, physical protection of nuclear materials, nuclear installations, radioactive sources, storage facilities for nuclear materials, radioactive substances and radioactive waste as well as the control of the observance by the Russian Federation of international and other agreements in force. We organise scientific research to substantiate the principles and criteria, the standards and rules for safe usage of atomic energy. We have responsibility

to inform the public and the state authorities about the safety status of nuclear installations, radiation sources and storage facilities. The Regulatory Agency operates from its Headquarters, Interregional Offices, Interregional Department for Information Gathering and Information Security as well as the Scientific & Engineering Centre for Nuclear and Radiation Safety. The interregional offices are located in seven regions and the Headquarters is in Moscow.

KSP : Administratively to whom do you report?

Mr.Vishnevskiy : We report to the President of Russian Federation. My reports and observations are sent to the Government. I shall send my remarks and points of view to the ministry if my directives are not complied with. Parliament helps me to speed up the Bills.

KSP : In the Peer Discussions, one of the issues which was discussed at length was the independence of the regulatory agency. The need to develop core competence in house was highlighted. While a great degree of independence can be achieved by incorporating appropriate legislation, there is no easy way to develop independent core competence in a short period of time. Since financial resources are limited, it is essential to avoid unnecessary duplication of research efforts. Fortunately in India we have the support of Bhabha Atomic Research Centre - a centre of excellence. ln fact many of us in AERB, spent several decades in BARC before joining AERB. What is your experience in Russia? Where do you get the technical and scienfific support from?

Mr.Vishnevskiy : Probably our situation is a bit easier. Though our first nuclear power reactor was commissioned in 1954, the regulatory organisation was set up only in 1984. We have several research institutes such as the Kurchatov Institute, the Academy of Sciences and Institute of Minnatom. Besides these, we have our own Scienfific and Engineering Centre for Nuclear and Radiation Safety (SEC NRS). As a matter of fact, at any time, there is some sort of competition between these institutions. We use this carefuly and effectively. We assign a task to one institution and request another institution to review their results. The SEC NRS co-ordinates all research efforts. Occasionally we send some projects to the Academy of Sciences.

KSP : Do you pay these institutions?

Mr.Vishnevskiy: (Smiles) Oh! Payments! all payments are made by the applicant. The Scienfific and Engineering Centre (SEC NRS) can hire any specialist. For adequate accomplishing the varriety of the problems the experts from other organizations are invited on the contract basis. SEC NRS renders the engineering and scientific support to the RF Gosatomnadzor; the research conducted by SEC NRS is the scientific ground for all other activities to support the Gosatomnadzor of Russia. The R&D works are directed to verify or validate the criteria and principles of nuclear and radiation safety used in the regulatory documents and for expertise. The SEC NRS carries out safety assessments of nuclear installations, radiation sources and storage facilities; participates in establishing the legislative basis in the field of the use of nuclear energy, nuclear materials, radioactive substances and radioactive waste management, as well as in the works aimed .at providing the legislative basis for nuclear and radiation safety regulation (except for sanitary and hygienic standards and rules).

KSP: In India, the Regulatory Board assisted the Government in drafting the Factory Rules as applicable to nuclear facilities and installations and administers them in those installations and facilities. During the discussions with other participants who attended the Peer discussions at the International Atomic Energy Agency I found that this practice is unique to India. What are the other responsibilities of SEC?

Mr.Vishnevskiy : 'Child as it was', SEC NRS was involved in nuclear safety issues only. Now, the terms of activity include all peaceful nuclear power facilities. SEC NRS conducts scienfific research to substantiate the principles and criteria for nuclear and radiation safety. The Centre verifies and validates computer codes, generates the concepts of and makes necessary entries into the data bases for safety assessment of nuclear installations, for radioactive substances and radioactive waste. The Concept of the State Control and Accounting for Nuclear Materials, approved by the Government of the Russian Federation, has been worked out with participation of SEC NRS.
Besides, SEC NRS conducts training of the staff, organizes workshops, seminars and
conferences, prepares for publication of various kinds of information materials and documentation authorized by the Gosatomnadzor of Russia.

KSP : Is the Regulatory Authority responsible for the safe application of radiation in the medical field?

Mr.Vishnevskiy : We do not consider how radiation is used by doctors. This is done by the Ministry of Health. But we issue licenses to use radiation equipment. We control the storage and transport of radioactive substances.

KSP : The Atomic Energy Act in India was adopted in the Indian Parliament in 1948. It was primarily meant to preserve natural resources or atomic minerals. In fact, radiation safety or nuclear safety requirements are not even referred to in the Act. This Act was repealed and replaced by the Atomic Energy Act 1962. A few Sections in the Act refer to safety requirements. Several rules under the Act have been promulgated over the years. How was the evolution of Atomic Energy Law in Russia?

Mr.Vishnevskiy : The Regulatory Board in the erstwhile USSR was set up in 1984. Then there was no Law as such. In the early years, there were some Decrees and Ordinances from the Party and Government. Gosatomnadzor was set up by a decree of the President of the Russian Federation in 1991. The competence, rights, duties and responsibilities of Gosatomnadzor and its officials are determined by the Provisions on Gosatomnozdor, approved by the President of the Russian Federation in 1992 and amended in 1993 and 1995.

KSP : What were the reasons for setting up the regulatory agency? Was it in the light of international developments?

Mr.Vishnevskiy : As far as I can recollect, there was no such reason. I am not able to indicate any specific reason for the development. After the accident at Chernobyl nuclear power station, we obtained more powers! Power to use sanctions, for instance. Chernobyl accident turned out to be a blessing in disguise!

KSP : But that was too expensive a way to secure regulatory power! I thought that everyone knew that nuclear technology at its current level of technology is an unforgiving technology.

Mr.Vishnevskiy : Not really. Probably more important than the regulatory agency getting more powers is that the accident brought about important changes in the minds of those who operate the reactors. Greater awareness in the operator.

KSP : What was the strength of the regulatory agency prior to the accident?

Mr.Vishnevskiy : Much less than now. Currently, the strength of Gosatomnadzer is 1000 plus; four to five fold increase since Chernobyl accident. Prior to the accident, there was no realisation that regulatory principles should be implemented fully in all nuclear power plants.

KSP: You mean that prior to the accident, regulatory principles were not formaly implemented in the nuclear power plants in Russia.
Mr.Vishnevskiy : I think, you can say so. Now our regulatory responsibility covers all stages of the nuclear fuel cycle, including mining, fuel fabrication, reactor operation, reprocessing and waste management.

KSP : For the regulator to be effective, he should be as competent and knowledgeable, preferably more competent and knowledgeable than those who operate the reactor. How do you achieve this? Do you offer any training to your staff?

Mr.Vishnevskiy : Yes, we have our training centre for training regulatory personnel.

KSP : Do you recruit young people to the regulatory agency?

Mr.Vishnevskiy : As a matter of fact, no new comer joins the regulatory agency. We recruit people of average age with experience in industry

KSP : What is the incentive for experienced people to join the regulatory board?

Mr.Vishnevskiy : There are different reasons. Stable job, stable government job. They have some advantages after retirement. A lot of people joined because of their interest. For instance, I myself came; my deputy joined. In principle we could have setfled down in reactor operation. But we concluded that we can improve safety. Nuclear power has future only if we reach a certain level of safety.

KSP: Mr Vishnevskiy, you have rich and varied expertise and experience and you are currently occupying the chair of the top regulator in the Russian Federation. Can you tell us about any unique and memorable era in your career?

Mr.Vishnevskiy : Unique and memorable era! I was a Member of Parliament for some rime. I made speeches to my electorate! Then the situation was different. That was way back in 1990. 1 was elected from the region in which I was staying then. I was then serving the government.
KSP : Can government officials contest elections?

Mr.Vishnevskiy: Government staff could contest elections then. Now there is a law against it. In 1993, 1 resigned as an M.P.

KSP : You must have enjoyed a high level ,of popularity?

Mr.Vishnevskiy : It was unique. I also learnt that life is not a bed of roses.

KSP : One of the important functions of any regulatory authority is to inspect the installations to ensure compliance with safety requirements. How is inspection of nuclear installation carried out in the Russian Federation?

Mr.Vishnevskiy : We have the system of resident inspectors at the NPP sites. We post the group of five inspectors per site, one Chief Inspector and four inspectors. They belong to different disciplines: radiological safety, lnstrumentation and Control, etc.
In the regulatory authority, the licensing and inspection sections are kept separately. We assign inspection work to specialists, they visit the utility and make recommendations.

KSP : How did you enter the regulatory field?

Mr.Vishnevskiy : I attended a special technical course in technical institute which has special faculty working in the nuclear and engineering physics. I have graduated with specialisafion in management of Nuclear Power Plants. In 1966, 1 graduated in engineering and physics and joined a nuclear power plant. In 1985, 1 entered the regulatory field.

KSP : Whenever the issue of public awareness come up for discussion in the Peer Review meeting, you argued passionately in favour of various public information programmes. What is the role of Gosatomnadzor in the area?

Mr.Vishnevskiy : We keep contact with mass media, hold meetings in which representatives of the regulatory authority meet public organisarion, information agencies and private persons. In order to coordinate these activities we established the Interregional Territorial Department of Information gathering and Information Protection as a Public Relations Division. Summarised information on the nuclear and radiation safety status in the country is sent monthly to the main information agencies in Russia. The information is transmitted to the electronic mass media regularly. In case of an emergency they will receive updated 'fresh' information.

KSP : AERB publishes its annual report. We publicise the regulatory restrictions placed on nuclear installations. The fact that AERB - a government agency - can place restrictions on government nuclear installations appears to improve the credibility of the Organisation. The restrictions include reducing power levels of nuclear power plants, delicensing of crew and occasionally shutting down installations. What do you do to improve the credibility of your organisaflon? Have you taken any special steps?

Mr.Vishnevskiy : In Russia nuclear power plants are in the government sector. Nuclear industries (industries producing nuclear components and system) might also be the private enterprises. The credibility question can be easily solved. My prescription is: don't tell a lie, be honest, open and transparent. I invite Green Peace. I discuss safety issues with them. I get a lot of material from their placards and transparencies. Many such information, I receive, I may not get from normal government channels.

KSP : Where were you when the accident occurred at the Chernobyl Nuclear Power Station?

Mr.Vishnevskiy : I was the then Chief Inspector at the Balakovo Nuclear Power Station. We were just finishing the tests to start up the reactor.

KSP : How did the people react?

Mr.Vishnevskiy : Nobody could understand that such an accident can happen. We spend time investigating the possibility of such accidents in VVER, the Russian version of the Pressurised Water Reactor

KSP : Chernobyl power reactors had known deficiencies.

Mr.Vishnevskiy: Frankly speaking, there were some observations on the weaknesses of Chernobyl reactors. But nobody could foresee that
the deficiencies could lead to such a reactor accident. To create such accidents, many events were to be postulated or imagined.

KSP : How was the attitude of the staff?

Mr.Vishnevskiy : Before the accident, the attitude of the management towards the nuclear power reactor was the some as towards a conventional power station. The only difference was that they know that one is 'a nuclear boiler' and the other 'a conventional boiler'. But after the accident of Chernobyl Nuclear Power Station, there was clear change in the attitude. They started respecting the process of nuclear reactions.

KSP : What were the criteria followed to evacuate the population from the contaminated zone around the reactor?
Mr.Vishnevskiy : After the accident specific measures were taken. We measured the radioactivity levels at different areas and divided them into different zones depending on the radioactivity levels. On this basis, we decided from which zone people will have to be removed. We decided that people should be evacuated from all the zones in which they are likely to be exposed to more than 35 Bert in 70 years. (Bert was mentioned as the Unit it appears to be equal to rem).

KSP : Did the staff of nuclear power stations leave in large numbers?

Mr.Vishnevskiy : Some people left. Others did not.

KSP : Has the accident affected the morale of the staff?

Mr.Vishnevskiy : No, it did not. Certainly it did influence some people coming to the faculty of nuclear science. Now we have fully recovered. Now there is competition among people!

KSP : If you have the option, would you advise your son to join the nuclear field?

Mr.Vishnevskiy : My son is in the nuclear field! Earlier he worked in a nuclear power station. Now he is member of staff of Scientific and Engineering Centre for Nuclear and Radiation Safety.

KSP : What is the future of nuclear power in the world? There is a move against nuclear power in several European countries.

Mr.Vishnevskiy . It is a challenging question! Nuclear power contributes substantially to the total power generated. I don't think we can eliminate nuclear power completely.

KSP : What is the future of fusion power?

Mr.Vishnevskiy : It is difficult to say. Even if fusion power becomes reliable, the cost is likely to be high. I think it may take 10 - 20 years of further technological development.

KSP : India has consciously planned to set up a three stage nuclear power programme. Our ultimate goal is to make use of the vast resources of thorium available in the country as our uranium resources are modest. How is the programme envisaged in the Russian Federation?

Mr.Vishnevskiy: We have established the thermal reactor technology. We have reactors of advanced design under planning stage. We have considerable interest in breeder reactors. There are economic issues, fast reactor fuel is costlier. Currently, our breeder programme is at stand still. We have to continue R&D in this area to develop newer concepts. We are carrying out work in the liquid metal cooling system.

KSP : It is known that Pressurized Water Reactors become popular because lot of development work has gone into them while nuclear submarines were constructed. What was the background in the development of RBMK reactors?

Mr.Vishnevskiy : Such reactors were primarily used to produce plutonium.

KSP : It is reported that Chernobyl nuclear power station had performed extremely well and had achieved record levels of power production. Was it one of the reasons for complacency? Was it one of the factors which led to the nuclear disaster?

Mr.Vishnevskiy : Chernobyl power station performed well. Today we may say that complacency was one of the reasons for the disaster. The operators were known to be skilled specialists. Production of power was their main goal.

KSP : You have spent the earlier part of your career as a nuclear operator. Now you are Chief of the Regulatory Organisation. There was on going debate on the various factors that led to the accident at Chernobyl Nuclear Power Station. The designers blamed the operators and the operators blamed the designers. Recently a physicist from Russia's Kurchatov Institute disputed the official version. An interview with him appeared in the January issue of Nuclear Engineering International. What is currently the official position?

Mr.Vishnevskiy : Right in April, the Russian Academy of Earth Sciences published another reason. According to them, there was a localized earthquake close to Unit 4, the bottom structure of the unit developed a crack. There are different versions. Therefore, I cannot comment finally. Now we are closely reviewing all opinions.

KSP : How did the Laws relate to Atomic Energy develop in Russia?

Mr.Vishnevskiy : The Federal Law on the Use of Atomic Energy was issued in 1995.
This was followed by the Federal Law on Radiation Protection of Population in 1996. Earlier the practice used to be to issue Decrees or Ordinances. When I was a member of Russian Supreme Soviet, I took part in the drafting of the Low.

KSP: The regulatory mechanism in India evolved gradually. Till 1983, the regulatory work was carried out in house. The regulatory procedures and the mechanisms established have been the subject of review of high level committees of specialists. These have evolved and were strengthened as per national requirements. How was it done in Russian Federation. Is there any peer review of the regulatory agency?

Mr.Vishnevskiy : No, we do not have formal peer review of the activities of the regulatory agency. We function very carefully. We are able to show that we act as per the international requirements.

KSP : One of the most important areas of activities in the nuclear field is the management of radioactive wastes. What is the role of the Russian regulatory agency in the area?

Mr.Vishnevskiy : Our main role is in the development of scientifically well supported and justified criteria. Our role is that of an initiator. For example, before the establishment of the regulatory board, radioactive wastes were put underground. Today we do not provide a licence for it. We prohibit such a procedure. We require additional justification for the safety of such a method.
Actually, waste management is a common job. Regulatory agency work with the utility and the government will support the programme. Today we have started a programme to manage radioactive wastes.

KSP : Decommissioning of nuclear submarines is reported to be another important area. How big is the issue? What is the responsibility of regulatory agency in the area?

Mr.Vishnevskiy : Speaking precisely, we just started supervising the programme. This activity is with the Defence Department right now. Department of Defence is transferring the responsibility to Department of Atomic Energy. Then the programme will come under the supervision of the regulatory body. Currently we are developing the conceptual approaches ourselves. Decommissioning unused nuclear submarines is an important safety issue.

KSP : Exhaustive and dedicated review of certain areas is one of the ongoing activities of the Atomic Energy Regulatory Board. Thirteen such reviews have been completed So for. Some of these are identical to the IAEA Operational Safety Review Team Mission. Do you organise such programmes.

Mr.Vishnevskiy : We do conduct reviews of certain topics such as strength of containment matters connected with the new design of breeder reactors, Design of VVER for India among others.

KSP : Thank you very much Mr. Vishnevskiy. I am very grateful to you for sparing your time to convey your views on very wide ranging subjects.

Technologies to harvest uranium from sea

2009-11-15T10:19:00.004+05:30

India has made modest progress in extracting uranium from sea water. The quantity still remains in milligrammes. There are plans to "scale up" the facilities

K.S.Parthasarathy

Date:12/11/2009 URL: http://www.thehindu.com/thehindu/seta/2009/11/12/stories/2009111250321300.htm
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Back Sci Tech

Technologies to harvest uranium from sea
There are 4.5 billion tonnes of uranium in sea water, a thousand times more than what is known to exist in uranium mines

The way ahead: BARC and the Commissariat a’ Energie Atomique (CEA), France, are collaborating to develop three innovative and efficient methods of uranium extraction.
Uranium in trace quantities is present in soil, rock and water. Bounteous nature leaves about 4.5 billion tonnes of uranium in sea water, a thousand times more than what is known to exist in uranium mines. Since its concentration is extremely low (only one particle of uranium for 34 million particles of other elements), harvesting uranium from sea is a formidable task.
Japanese technology
Japan developed a technology by using plastic sheets to which amidoxime, which is capable of selectively absorbing uranium from seawater, is grafted by high energy electron beam irradiation.
Scientists from the Desalination Division, Bhabha Atomic Research Centre recovered uranium at milligram levels from sea water using electron beam grafted amidoxime.
They developed a semi pilot scale facility to produce radiation grafted sheets of 1 metre X 1 metre size.
They collected about 800 microgrammes of uranium in five campaigns from CIRUS Jettyhead; about 1.8 milligrammes from the seawater intake and outfall canals at the Tarapur Atomic Power Station and around 200 microgrammes from Andaman and Nicobar Islands. Though these amounts are trivial, it gives confidence in the technology
Field trials carried out at the three locations gave concentration factors of 300, 600 and 700 for the submergence of the absorbent material for 12, 14 and 23 days respectively.
“What are the reasons for obtaining different concentration factors at different locations?” “The concentration factor depends on corrosion, bio-fouling and their combined effect on the adsorption kinetics. These may be different at different locations”, Dr P.K. Tewari, Head, Desalination Division, BARC responded to my query.
BARC scientists studied these factors and the mechanical properties of the materials used in the suspension assembly and the substrate. They established their compatibilities with seawater and process chemicals and the optimum submergence periods for various locations.
They also evaluated the potential of Polyhydroxamic Acid (PHOA) sorbent, for uptake of uranium from seawater. They obtained a concentration factor of over 190, when the resin, filled in a porous bag was dipped in seawater for a period ranging from 10-30 days.
BARC and the Commissariat a’ Energie Atomique (CEA), France, are collaborating to develop three innovative and efficient methods of uranium extraction from the concentrated brine rejected by integrated nuclear desalination systems, which both partners are currently developing.
The first method uses resin-grafted with calixarene (a synthetic material, indecently expensive!); magnetic separation is the second method and the third uses a canal system using absorbents.
These methods are highly selective but need further research and development.
Using three absorption cages, each of cross sectional area of 16 square metres and height of 16 cm and consisting of stacks of 52,000 uranium specific, non-woven sheets with a total mass of 350 kg, a Japanese group recovered more than one kg of uranium in terms of yellow cake during a submersion period of 240 days in the ocean.
Underwater farm
Dr Masao Tanada of the Japanese Atomic Energy Agency hopes to get funding to construct an under-water uranium farm covering nearly 400 square miles that would meet one-sixth of Japan’s annual uranium requirements.
Tanada asserts that Japan’s nuclear power industry can harvest the 8,000 tons it needs annually from the Kuroshio Current that flows along Japan’s eastern seaboard.
Japanese researchers found out that they can harvest uranium from sea by cultivating genetically engineered gulfweed which will grow in sea at an unbelievable rate of two metres an year. The weed selectively soaks up heavy metals including uranium.
A spin-off
What will you do with possibly the millions of tons of grass left over after recovering uranium? Convert it to bioethanol! Gulfweed is an ideal non-food source of bio-ethanol. Gulfweed traps carbondioxide from sea.
Conventional uranium mining requires environmental restoration including long term tailings management. Uranium recovery from the sea does not leave any tailings. With superb green credentials, it is an environmental friendly process.
India has miles to go to reach kilogramme capacities of uranium. BARC has plans to upgrade the capacity.
K.S. PARTHASARATHY
Raja Ramanna Fellow, Department of Atomic Energy
( ksparth@yahoo.co.uk )
© Copyright 2000 - 2009 The Hindu

High fissile fuel in nuclear submarine lasts long

2009-11-05T21:10:00.003+05:30

High fissile fuel in nuclear submarine lasts long

The prototype is serving as a training centre for the nuclear submarine crew

Reactor internals must be rugged and resilient

Reactor internals remain inaccessible for inspection

Every year, on October 30, scientists, engineers and other officials from the Department of Atomic Energy gather near the Central Complex Building, Trombay to celebrate the Founder’s Day. Being the Birth Centenary year of Dr. Homi Bhabha, this year’s celebration was unique. The stock taking of the research and development activities at the Bhabha Atomic Research Centre (BARC) covered compact reactor for Arihant (the nuclear submarine), improved gas centrifuges for uranium enrichment, fuel fabrication for fast reactors and work on innovative reactors among other areas in the cutting edge of technologies.

BARC designed, developed and built the steam generating unit of Arihant by facing many technical challenges

“The compact Pressurized Water Reactor was designed for this purpose with several features; such as very quick response for power ramping, extremely stable undership motions and resistance against exposure to very high acceleration resulting from eventual depth charges”, Dr Sukumar Banerjee, Director, BARC said in his Founder’s Day Address

“Since the nuclear reactor is fuelled with high fissile containing fuel, it can supply energy in the submerged condition for an extended period without refuelling”, he clarified. Details about the reactor are classified.

Generally, Pressurized Water Reactors (PWR) power nuclear submarines. A PWR has a core of highly enriched uranium. When uranium nuclei undergo fission, the fission fragments carry enormous energy. They dissipate the energy in the core which gets heated up. The high pressure primary system with water as coolant removes the heat from the core continuously.

Water at high temperature enters the steam generators. In the steam generators, the heat from the water in the primary system is transferred to the secondary system to create steam. In the secondary system, the steam flows from the steam generators to drive the turbine generators, which supply the ship with electricity, and to the main propulsion turbines, which drive the propeller. After passing through the turbines, the steam condenses into water which is fed back to the steam generators by the feed pumps.

Naval reactors pitch and roll. Demands of power change rapidly. The manufacturing and quality assurance of reactor components must be of exceptionally high standard.

The reactor internals remain inaccessible for inspection or replacement throughout the long life of their core. They must be rugged and resilient. Reactor components and systems must withstand, harsh and hostile environment, long term effects of radiation, corrosion, high temperature and pressure.

As the reactor operates radiation level increases. Appropriate shields are built around the reactors to ensure radiation safety. A reactor may use over 100 tons of lead as shielding.

“Many systems and equipment designed and built were first of its kind in the country. The entire steam generating plant has been designed to give highly reliable offshore operation in a completely isolated environment”, Dr Banerjee noted.

“Control and instrumentation design is fault tolerant and requires minimum operator interventions. An elaborate diagnostic system enables a very high availability factor. Many new materials and technologies have been developed and new infrastructure has been created for this project”, he revealed.
Prototype system

The development of the steam generating plant of Arihant was preceded by setting up of the land based prototype system at Kalpakkam. The reactor which has been working for the past three years has served as a technology demonstrator.

“The entire plant with primary, secondary, electrical and propulsion system along with its integrated control was packed in the aft end of a land based submarine hull designed and built specifically for the purpose.

This protoype is serving as a training centre for the crew for the nuclear submarine”, Dr Banerjee said. The crew gets training with the help of an indigenously designed and built full scope simulator.

K.S. PARTHASARATHY

Raja Ramanna fellow, Department of Atomic Energy

( ksparth@yahoo.co.uk)

© Copyright 2000 - 2009 The Hindu

Can low doses of radiation cause heart disease?

2009-10-29T04:55:00.008+05:30

It is necessary to assess the epidemiological evidence of radiation effects other than cancer at low doses

Basic guideline: The basic tenet of radiation protection that radiation doses to workers should remain As Low As Reasonably Achievable remains.

Researchers at the Imperial College, London predict a link between low dose radiation exposure and heart disease (PLoS Computational Biology, October 2009). Their mathematical model suggests that the risk would increase as the dose increases.
Cardiovascular effect of high levels of radiation has been known in patients who underwent radiotherapy. Specialists found higher risk for cardiovascular disease among women treated for left-sided breast cancer when compared with women treated for right-sided breast cancer, during the period more than 10 years after diagnosis.
Emerging evidence
There is emerging evidence of excess risk of heart disease at much lower doses occurring after a long time after exposure among the A-bomb survivors included in the Life Span Study project and in some groups of radiation workers. The likely mechanism to explain the effect was not clear.
The US National Academy of Science’s Committee for Biological Effects of Ionizing Radiation (BEIR committee) in its latest report has acknowledged the existence of such effects; it asserted that the available data are inadequate to quantify the risk, if it exists.
The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) in its latest report published in 2008, clarified that it is necessary to assess the epidemiological evidence of radiation effects other than cancer at low doses because the phenomena is potentially important for radiation risk assessment at these dose levels, and there is considerable lack of consistency among the available epidemiological data.
“The Committee considered it important to focus on cardiovascular disease as the major endpoint of interest, because cardiovascular disease is among the most common diseases in many populations worldwide and thus may be important for radiation risk assessment,” the report cautioned.
The Imperial College team suggested that radiation kills monocytes (a type of white blood cell) in the arterial wall, which would otherwise bind to monocyte chemo-attractant protein 1 (MCP-1). The resultant higher levels of MCP-1 cause inflammation which leads to cardiovascular disease.
According to the researchers, the predicted consequence of several small radiation exposures is to cause mean concentration of MCP1 to increase linearly with cumulative dose.
“The radiation-induced risks predicted by the model is consistent with those observed in a number of occupationally observed groups,” they claimed.
The implications
According to them, if their model is valid, it will have substantive implications in radiological protection, which currently does not take cardiovascular diseases into consideration.
In an interview to BBC, Professor Steve Jones, of Westlakes Research Institute who formerly worked for British Nuclear Fuels (BNF) and who has published his own research on the links between radiation and circulatory disease in nuclear workers conceded that the results of the mathematical model were interesting. He cautioned that its finding cannot be taken as definitive as it is based very largely on mathematical modelling.
“However it does propose a plausible biological mechanism and, most importantly, a mechanism that is testable by experiment.” he clarified to the BBC.
BBC quoted Professor Richard Wakeford, of the University of Manchester who also formerly worked for BNF, thus: “More research like this is needed if the results of epidemiological studies are to be properly understood, but there is still some way to go before it may be reliably concluded that low-level radiation can increase the risk of circulatory disease.”
According to BBC, Professor Dudley Goodhead, former director of the MRC Radiation and Genome Stability Unit, noted that this paper puts forward a highly complicated mathematical model, which makes many assumptions, to explore one possible causal mechanism.
“Such conclusions should not be drawn without laboratory validation of the key assumptions,” he asserted.
For many years, the model proposed by the Imperial college team may remain just that; a model with no practical implications.
The basic tenet of radiation protection that radiation doses to workers should remain As Low As Reasonably Achievable (ALARA principle) remains.
Scientists from the Regional Cancer Centre, Thiruvananthapuram and Bhabha Atomic Research Centre did not find any excess cancer in the high background radiation areas (HBRA) in Kerala. It will be worthwhile to look for excess cardiac diseases in HBRA.
K.S. PARTHASARATHY
RAJA RAMANNA FELLOW, DEPARTMENT OF ATOMIC ENERGY
ksparth@yahoo.co.uk
© Copyright 2000 - 2009 The Hindu

How safe is Madras Atomic Power Station?

2009-10-24T21:47:00.006+05:30

South Asians Against Nukes (SAAN) , a Non Governmental Organization has claimed that the radiation levels are high in regions around the Madras Atomic Power Station. They measured the levels by using their own gamma monitor. The results indicate either that they were measuring the widely varying background radiation levels because of the presence of thorium in the soil or they wee using a defective instrument. Since they obtained abnormally high values, there instrument must have been defective!

The author had similar experience when another NGO claimed that the background radiation levels in Lucknow was very high. It turned out that the instrument they used was light sensitive!

K.S.Parthasarathy

How safe is Madras Atomic Power Station?

Within threshold: The releases from the Madras Atomic Power Station have not exceeded the limits prescribed by the regulatory agency.

Background radiation level at any place depends mainly on terrestrial radiation from natural radionuclides such as uranium, thorium and their decay products and potassium-40 present in soil and on cosmic rays (radiation from outer space).
The top one metre soil in a land of area 0.1 acre anywhere in the country may contain 1.28 kg of potassium-40, 3.6 kg of thorium and one kg of uranium.
The soil factor
In different soils these values may be higher or lower. The dose due to natural radiation varies from place to place.
The releases from the Madras Atomic Power Station (MAPS) have not exceeded the limits prescribed by the regulatory agency. The data collected from 1982 to date by the Environmental Survey Laboratory (ESL) at MAPS do not indicate high increases in radiation levels. Nuclear Power Corporation Limited should invite students and public to the ESL to reassure them. BARC scientists have measured outdoor natural gamma radiation levels at 214 locations in different parts of India continuously over a year by using special dosimeters and got an average annual value of 775 microgray.
They got the highest value of 26730 microgray at Chavara, Kerala. (Gray is a unit of radiation dose.
Energy absorbed
When the dose is one gray, the energy from ionizing radiation absorbed is one joule per kg; since gray is a big unit, submutiples such as milli-one thousandth or micro -one millionth-of a gray are usually used).
Using the geological data on the types of rocks and the abundance of uranium, thorium and potassium in these rocks, BARC scientists prepared a radiation map of the country in 1986.
The natural background radiation doses at Mumbai, Kolkata, Chennai and Bangalore are 484, 810, 790 and 825 microgray per year respectively.
The annual cosmic ray dose itself varies from 280 microgray in Chennai to 440 microgray in Bangalore which is 921 metres above the sea level.
Variation of a few hundred microgray is not unusual.
What is the extra contribution, if any, to radiation dose made by a nuclear power station at its fence post?
Data from 1982 to 2007 indicate that for the MAPS, the lowest extra dose was 7.2 microsievert per year and the highest 86.3 microsievert per year. (Sievert — Sv — is another unit. For all practical purposes, background radiation expressed in sievert or gray may be considered numerically equal). These are much less than the AERB limit of 1,000 microsievert.
The status is similar in other power stations.
Activity can escape only if several barriers (ceramic fuel, its cladding, coolant, coolant tube etc) are broken. These are of proven quality. Fail safe devices including redundant and diverse safety systems ensure that such uncontrolled releases do not happen.
In April 1994, an “environmentalist” measured high radiation levels at the MLAs’ hostel and other locations in Lucknow. “Radiation levels at some points are higher than those at Chernobyl,” he claimed. Many newspapers published the story.
Recorded normal
A team of scientists sent by the Atomic Energy Regulatory Board (AERB) found that his Geiger-Mueller counter —based instrument was defective. It was light sensitive. When the detector was made light-proof, the radiation levels recorded normal!
In 2005, Padmanabhan and Nakul of the South Asians Against Nukes (SAAN) claimed that while monitoring radiation levels around the Madras Atomic Power Station in places such as Coimbatore, Chenglepet, Mahabalipuram and Kalpakkam they came across several spots with gamma radiation levels as high as a few millisievert to above ten millisieverts per year. The highest level measured was 54.5 millisieverts.
The speculation
They speculated that the wide variations between the readings taken from the same spot indicated that the source of radiation is not on the ground but are “picoparticles” from uranium fission floating and flying in air! There are simpler explanations.
If they were using a defect-free instrument, they were recording radiation from thorium rich soil in the region. This is nothing unusual.
Since over 70 per cent of their readings were above 2mSv, I believe that they were experiencing the problem faced by the “environmentalist” in Lucknow!
K.S.PARTHASARATHY
Former Secretary, AERB
( ksparth@yahoo.co.uk )
© Copyright 2000 - 2009 The Hindu

Nuclear power: myths, realities

2009-10-15T11:19:00.004+05:30

Nuclear power suffered because of accidents. But no one abandoned it because of accidents.Nuclear power seems to be an “unloved” industry, not because it is faulty. Mired in controversy, myths about nuclear power survive; the realities are unknown to many.Author highlights some of thew myths and the realities about this "unloved" industry
K.S.Parthasarathy

Date:15/10/2009 URL: http://www.thehindu.com/thehindu/seta/2009/10/15/stories/2009101550201400.htm Back Sci Tech

Nuclear power: myths, realities

Nuclear power suffered because of accidents. But no one abandoned it because of accidents

The impact of water used as coolant may extend up to about 500 metres from the discharge point

The doses to members of the public are too small and well within the AERB limit

The speakers at a well attended side event at the recently held International Conference on Peaceful Uses of Atomic Energy at Delhi (September 29-October 1) recommended a proactive, public awareness programme on issues related to energy, particularly nuclear energy.

International Atomic Energy Agency (IAEA), Department of Atomic Energy and Indian Nuclear Society jointly organized the meeting.

Nuclear power seems to be an “unloved” industry, not because it is faulty. Mired in controversy, myths about nuclear power survive; the realities are unknown to many.

Nuclear power suffered because of accidents. But no one abandoned it because of accidents at Three Mile Island (1979) and Chernobyl (1986).

U.S. electric companies connected 50 out of the currently operating 104 nuclear power reactors since 1979; nineteen of these after 1986. Canadian companies connected all the 14 operating nuclear power reactors to the grid after 1979. Of the fifty nine French reactors, 53 came on line after 1979.

Some European nations decided to phase out nuclear power. Since they are substitutes for fossil power stations (which are implicated in global warning), these nations are decisively moving away from their “phase out” decision.

Recently, “National Alliance of Anti-nuclear Movements (NAAM)” claimed that the nuclear plant at Kudankulam would lead to pollution in the near shore areas, affecting fish stocks. They alleged that this would impact on the health of fish-eating people in Kerala, Tamil Nadu and Sri Lanka (The Hindu, October 3). These allegations have no scientific basis. Pollution of sea shore is another myth!

Fish catch potential during 1994-98, in the Kalpakkam zone indicated variations. Central Marine and Fisheries Research Institute, Cochin, concluded that these variations are mere statistical variations with seasons.

The impact of water used to cool nuclear power reactors is limited to a mixing zone which may extend up to about 500 metres from the discharge point.

India has been operating nuclear power stations since 1969.

The Atomic Energy Regulatory Board (AERB) permits stations to release radioactivity up to certain prescribed limits. The scientists at the Environmental Survey Laboratory (ESL) outside each station use state-of-the-art methods to measure radioactivity in samples of air, water, soil, sediments and foodstuffs and look for trends, if any.

The doses to members of the public are too small and well within the AERB limit. They are within the variation of natural background radiation present everywhere even in the absence of the power station.

The radiation dose due to Kudankulam reactors will also be similar. An activist alleged that these reactors would trigger cancer and genetic disorders in the area (The Hindu, Oct, 3). This is a preposterous allegation.

The claim that iodine-131 released from Kalpakkam nuclear power station into sea and air is causing thyroid cancer in the area in another myth.

The release of iodine to sea is virtually zero. During 1983-2008, the annual releases into air were zero to 1.29 per cent of the AERB limit. The doses due to this were too trivial to cause cancer.

The Iodine-131 activity, if any, released from the station will get deposited on grass. It will appear promptly in goats’ thyroid. ESL scientists routinely measure iodine-131 from goats’ thyroid, an easily available sample.

They detected iodine-131 activities only twice, in 1976 during the aftermath of Chinese nuclear tests in the atmosphere and in 1986 shortly after the accident at the Chernobyl nuclear power station.

“The ESL Kalpakkam had found after the nuclear accident at Chernobyl in April 1986 that the incidence of thyroid related diseases in goats had registered an increase as a result of feeding on grass laced with Iodine-131”.

An activist wrote in a Chennai daily on October 18, 2008 (NUCLEAR FREE INDIA, December 2008).Obviously, he mistook why ESL scientists collect goats’ thyroid samples!

According to an activist, the scientific community was yet to come up with a safe nuclear waste management system (The Hindu Oct, 3). Another myth!

Nuclear wastes are managed safely. There is scientific consensus on safe management of high level nuclear waste; but that problem is mired in politics.

If you want nuclear power to thrive, dispel the myths, reveal the realities!

( ksparth@yahoo.co.uk )

K.S. PARTHASARATHY
FORMER SECRETARY, AERB

How safe are interventional cardiac procedures?

2009-10-02T19:26:00.003+05:30

Radiation safety in interventional radiology practices are getting some attention now
The Hindu published an artcile on October 1, 2009
Dr K.S.Parthasarathy

Date:01/10/2009 URL: http://www.thehindu.com/thehindu/seta/2009/10/01/stories/2009100150441500.htm
________________________________________

How safe are interventional cardiac procedures?
— Photo: S. Thanthoni

Within threshold: Radiation risk is acceptably low when compared to risk of not carrying out the procedures when indicated.
Recently, radiation protection measures in interventional radiology especially in cardiology have been receiving special attention.
These are image-guided therapeutic techniques such as coronary angioplasty (to remove blockades in artery) and diagnostic techniques such as angiography (imaging the blood vessels using an x-ray contrasting agent).
These life-saving procedures require specially designed equipment and involve high radiation exposures to physicians, technologists and patients. Cardiologists must know the equipment specification and characteristics to use radiation effectively and optimally.
Risks compared
Radiation risk is acceptably low when compared to risk of not carrying out the procedures when they are medically indicated.
Recently, a survey supported by the International Atomic Energy Agency (IAEA) in 55 hospitals in 20 countries of Africa, Asia, and Europe indicated that many patients exceeded the dose threshold for erythema (skin reddening); a substantial number (62 per cent) of coronary angioplasty procedures exposed patients to doses above the recommended dose reference level. (American Journal of Roentgenology, August 2009). Though specially needed dose measuring instruments were in place in almost half the facilities, none had experience in its use.
Hundred out of 505 patients monitored, had peak skin doses above the 2-Gy threshold for deterministic effects (Gy is a unit of radiation dose; one Gy is equal to one joule per kg).
Inadequately trained
IAEA has noted that many physicians using interventional radiology techniques are not adequately trained in radiation safety or radiobiology. In a few cases, patients may suffer radiation-induced skin injuries which may go unnoticed. Younger patients may face an increased risk of future cancer.
Patients may ask their physicians about the radiation dose they are likely to get in the procedure. If they feel any changes in the exposed area of the skin later, they must report it to their physician. Though radiation dose is important, it is only one of the factors to be considered.
The dose to patients must be As Low As Reasonable Achievable (ALARA). Cardiac procedures are very complex, doses will be ALARA only if the cardiologists appreciate the importance of dose reduction; they must be constantly vigilant. If patient’s dose is reduced, occupational dose also will be reduced.
A few years ago, a medical physicist working in a corporate hospital introduced me to an eminent cardiologist who has been saving hundreds of lives. “When I have too many patients, I just remove the personnel monitoring badge”, he confessed. Unknown to him, he may become a victim of his carelessness.
Regular monitoring
Cardiologists must monitor their radiation doses regularly; they are among the category of radiation workers who have highest probability to get significant doses.
IAEA surveys conducted during training courses in which cardiologists from 56 countries participated showed that only 33 to 77 per cent of them use personnel dose measuring devices routinely.
During a workshop in Mumbai two cardiologists listed several telling deficiencies ( http://www.aerb.gov.in/t/newsflash/cathlab.pdf).
Cardiologists are not aware of the radiological safety precautions to be taken during angiography or angioplasty. They lack awareness of personal protective equipment, personnel dose monitoring devices and their proper use.
Lens of the eye is radiosensitive. Cardiologists remain near x-ray sources within high scatter radiation areas for several hours every day.
Preliminary results from the IAEA study called Retrospective Evaluation of Lens Injuries and Dose (RELID) indicate identifiable damage to the lens of those cardiologists not using eye protection.
A summary of the results of studies carried out in Colombia, Malaysia, Uruguay and Bulgaria during 2008-09 is freely available (http://rpop.iaea.org/RPOP/RPoP/Content/News/relid-activities.htm). Protracted eye lens dose of 4Gy over 3 months or 5.5 Gy delivered over five months may cause detectable opacities to the eye lens.
IAEA has been very active in the field of radiation protection. They offer educational material of inestimable value free at their web site (http://rpop.iaea.org/).
The International Commission on Radiological Protection has issued its publication No 85 titled “Avoidance of radiation injuries from medical interventional procedures” ( http://www.icrp.org/
educational_area.asp).
K.S. PARTHASARATHY
Former Secretary, AERB
( ksparth@yahoo.co.uk )
© Copyright 2000 - 2009 The Hindu

Scientists find direct link between CT scan and cellular damage

2009-09-13T09:59:00.004+05:30

S & T » Science
August 18, 2009
Scientists find direct link between CT scan and cellular damage
K. S. Parthasarathy

A new research paper shows that radiation doses over time were less damaging than a single dose delivered all at once. In this 2005-file photo, a patient undergoing a test on computed tomography multi-detector 16 slice scanner at a hospital in India. Photo: K. R. Deepak.
Related
TOPICS
science and technology science (general)
health
X-rays induce many types of lesions (tiny biological damage) in the tissues through which they pass. They include breaks of one strand or both strands of the cellular DNA. Cells repair most of the former lesions promptly. Double Strand Break (DSB) is probably the most important effect. Scientists have developed extremely sensitive methods to assay DSBs caused by a single computed tomography (CT) test.
Cell repair
Cells can either repair DSBs properly restoring overall integrity of the genome, or mis-repair, resulting in drastic consequences such as cancer.
Kufner, Schwab and colleagues, researchers from Germany, described a method to measure biological dose in computed tomography (CT) scanning procedures (European Congress of Radiology, 2009). They demonstrated Double Strand Breaks (DSBs) of DNA in the white blood cells of patients undergoing cardiac CT and angiography examinations by sampling blood from the patients before and after the tests.
Physical energy absorbed by tissue is an imperfect indicator of what goes on in the tissue. A true estimate of radiation risk requires an accurate, reproducible biological measurement of radiation-induced damage, (auntminnie.com, 2009). By counting the DSBs, the researchers measured such a biological quantity.
Assay method
Radiation exposure causes DSBs in mammalian cells. When cells are exposed to radiation, certain types of molecules called histone H2AX, adjacent to the nascent breaks, undergo “phosphorylation” (a process involving specific biochemical changes).
The response is highly amplified and rapid; hundreds to thousands of H2AX molecules join within minutes. This newly phosphorylated protein called gamma-H2AX mobilises DNA repair proteins and form discrete foci, one per DSB. Specialists count these biomarkers by using immuno-fluorescence microscopy.
Counting of DSBs is thousand times more sensitive than other biological methods such as counting of chromosome aberrations.
A dose of one mGy (typical skin dose in medical x-ray examinations) generates on average one track per nucleus and thus is considered the lowest dose that can affect a whole cell. With one mGy, nearly 3 per cent of irradiated cells can sustain a DNA DSB. (Bonner, Proceedings of the National Academy of Sciences, April 23, 2003)
Medical X–ray procedures
Researchers examined 32 patients, 16 on each of two CT scanners using various protocols. They collected blood samples before and 30 minutes after the CT scan and counted the DSBs formed. They found that the number of DSBs increased linearly with dose length product, a normally used physical parameter
They observed that sequential CT scans are less biologically damaging than spiral CT. Radiation dose delivered over time was less damaging than the same dose delivered all at once. They did not observe any abnormal DNA damage in the blood cells of interventional radiologists when measured repeatedly throughout the normal working day.
The researchers demonstrated the presence of DSBs in the blood cells of all 37 patients undergoing conventional angiography. The number of DSBs at the end of the procedure varied widely, declining rapidly after the examinations due to DSB repair processes.
The sensitive methods evolved by the researchers may be very useful in understanding the mechanisms of cellular damage. It may help to evolve better cancer treatment strategies. Cancer cells are rogue cells with no rules. If they have any rules they are their own rules!
CT, a unique tool
The findings referred to in this article indicate the unparalleled technological advances in the study of cells and do not in any way diminish the potential use of computed tomography or conventional angiography in clinically indicated instances. CT scan unit is a unique tool to diagnose disease, trauma or abnormality and to plan, guide and monitor treatment.
It will cause harm to the patient if he refuses CT examinations prescribed by a qualified physician. For such tests, the benefit far outweighs the possible harm. Technological revolutions should not skew perception of risks.
(The author is a Former Secretary, Atomic Energy Regulatory Board, India. He can be contacted at: ksparth@yahoo.co.uk )
Keywords: CT Scan, DNA, K.S. Parthasarathy, Radiation,
________________________________________
Printable version | Aug 22, 2009 8:24:48 AM | http://beta.thehindu.com/sci-tech/science/article4850.ece

Interview with Profesor Roger Clarke, Chairman, International Commission on Radiological Protection

2009-08-12T17:46:00.001+05:30

EXTRACT OF THE INTERVIEW GIVEN BY Prof. Roger Clarke, chairman, International Commission on Radiological protection to Dr. K.S. Parthasarathy, Secretary, AERB during his visit to India to participate in the International Conference on Medical Physics and the XIXth annual Conference of Association of Medical Physicists of India

( Published in the AERB Newsletter)

Dr. KSP : I remember that it is not your first visit to India

Prof. Roger Clarke : I cam to India a few years ago. But I am attending the Medical Physics Conference for the first time.

KSP : In your last visit you addressed the officers of the Atomic energy Regulatory Board (AERB).

RC : I know a few colleagues from India who worked with me in the Committees of the International Commission on Radiological protection.

KSP: How did you get into the field of radiological protection? What was the incentive to enter this field? The career of a radiation physicist may not have been lucrative. Is it not?

RC : I was a reactor physicist working for the Central Electricity Generating Board (CEGB). One day my head of Division came to me. He wanted an answer for the question, with how many failed fuel plus pins you can operate an Advanced Gas Cooled Reactor (AGCR). It was in the Sixties. AGCR fuel was more expensive. Primarily the emphasis was on the basis of those to the public. I collected relevant data. In the process, I calculated the inventory of the fission products. I got introduced to health physics. I did some environmental modeling, got interest in radiobiology. Later I joined the National Radiological Protection Board to establish close assessment capability after gathering inputs on the environmental concentration of radionuclide. There was a group working on the movement of radionuclide in the biosphere. This was 20 years ago. This group was primarily interested in the study of radiation doses due to releases of radionuclide.

KSP: Historically, the International Commission on Radiological Protection (ICRP) was setup to make recommendations on the safe use of ionizing radiation in medicine. But it took a few decades for ICRP to bring out comprehensive recommendations on the protection of patients in diagnostic radiology. What was the reasons for this? Was it because ICRP did not want any control on medical radiation proactive?

RC : In the early years, therapeutic treatment was given more emphasis. The forerunner of the ICRP originated from the recommendations of the British X-ray and Radium Protection Committee. Then the major concern was protection of the workers. This was because deterministic effects such as extensive skin damage was seen among the x-ray workers who handled x-ray units. After the Second World War more penetrating radiations came to be used in medicine. Artificial radioisotopes appeared on the scene. More and More public were exposed. The emphasis shifted to public exposure. It coincided with more developments in fifties the emphasis was on therapy. Later more and more diagnostic technologies were developed.

KSP: Is it true that after the Second World War, many technically qualified people entered the job market. Many of them were electrical engineers. Apparently, this gave a boost to the development of newer technologies, which included manufacture of x-ray generations of higher and higher voltages.
RC : That is true. Radiation generators emitting more penetrating radiation began to appear in medical practice. Leukemia was identified among medical practitioners. The work by an American Physician Mr. Shields Warren is notable. He reported that Leukemia among radiologists was higher than that among general medical practitioners. It was obvious that ICRP, in this background, started giving more emphasis to patient protection. I would like to mention one recent development. Deterministic effects are coming out into focus now. Some of the interventional procedure, if carried out without care, can give substantial does to patients.

KSP: So it is not true that ICRP was somewhat biased in favour of radiologists over the years. What was the type of representation radiologists had in the ICRP?

RC: That ICRP charter states that only one radiologist need be there in ICRP though it was set up by the International Congress of Radiology – a professional association of radiologist – It is often not known that there are two more organizations to be considered, the International Commission on Radiation Units (ICRUs) and the International Committee for Education in Radiation and Radiology. The latter organization was established a few years back, but was not very active. It was re-established around five years back.

KSP: What are the new concerns?

RC: The concern of the radiologists shifted to finding out what is a better image. Future is in imaging, in medical imaging. For instance, digital imaging in interventional radiology, electronic manipulation of images, fluoroscopy with computer software. These technologies are likely to appear. More and more computer will start controlling x-ray imaging. Surgeons will turn round and expect computers to control the imaging procedure. With the newer techniques being used a dose reduction of a factor of about 10 is possible to the patient. The workers are also benefited by the dose reduction.

KSP: Do you agree that the scholarly discussion on the Linear-Non Threshold (L-NT)hypothesis has contributed to the notion that there is no safe level of radiation. Has it not sensitized the large public to greater and unreasonable levels?.

RC : I agree. When experts disagree, the credibility of specialists suffers. If experts do not agree, how can people decide which side of the argument is believable? I cannot deny that the arguments on L-NT has created some difficulties. The situation could be bad because there is an increasing possibility that decisions in science may be made by judges and juries in court rooms and not by professional association or by Royal Societies. The judiciary system may not be able to convince itself about the increased possibilities of radiation effects.
KSP: Don’t you thing that it is futile to try to get a deterministic answer to a purely probabilistic question?

RC: Yes. But I do not understand why some people wanted to establish that there is a threshold does below which there will not be any radiation effect. One of the major difficulties is in tackling the problem of old contaminated sites. Small radiation doses due to residual radio activities left behind at certain sites an cause very tiny amount of radiation doses. But when these doses are integrated over several thousand years. One may end up with getting significant amount of doses. We ill be left with the estimates of a few hundreds of probable deaths due to these collective doses accumulated over a long period of time. But I believe that we must have started dialogue on acceptable risks.

KSP : I am sure we must exclude voluntary risks such as risk due to smoking while we consider acceptable risks.

RC : Yes, I agree. Only involuntary risks are to be considered. In general, I am worried that the philosophy of protection has become somewhat complex.

KSP :Even for the professional ……..

RC : You said that and I agree. We must develop simpler concepts. ICRP must start consultations with other groups and collect ideas for reviewing and consolidating the system of protection. We have started to do that already. It explains why some of our recent documents are better than earlier ones. Consultation with others will help to improve the documents. The document on radon is an instance in point.

KSP: Everyone was keen on the on-going L-NT controversy. While the ICRP and the NRPB supported the argument that there is no threshold for the effects of ionizing radiation, the US Health Physics Society was unconvinced. The NRPB bulletin went to town with the suggestion that the attitude of the Health Physics Society is in tune with the liberalized attitude of US Administration to nuclear power. Can you comment on this development?

RC : Yes, certainly different professional groups looked at this issue very differently. American Health Physics Society has its own stated view. I have been to Health Physicists Society. Lots of people were interested in the controversy. The arguments put forth by the Health Physics Society are outdated with respect to the recent findings on the Japanese survivors of the atomic weapons. They did not then have the occasion to see the data. The recent data indicated that there could be significant risk at doses as low as 50 mSv, of course with much uncertainty. I do not still understand why they are looking for a threshold. There are many unknown cellular phenomena to be understood. Genomic instability, for instance.

KSP: You have become an unquestionable proponent of the linear non threshold theory. Certainly you didn’t ask for such a position. Do you really think that this controversy when uncontrolled?

RC: Yes. In my view, there is no need to search for a threshold. Nobody denies that there is evidence for the repair of cellular damage. But we cannot ignore that the repair mechanisms are also statistical in nature.

KSP: Biological effects of radiation has been studied for the past 100 years. The stochastic effects such as cancer world not have even been through about, but for the long an expensive epidemiological studies. Is it not unfair to spend too much of resources, in fact, vast sums of money to carry out studies about an agent which is now known to be much less hazardous than hundreds of toxic chemicals about which practically nothing is known.

RC: I may say that physicists should take the blame for it. The study of nuclear physics progressed rapidly. Some of the best brains entered the profession. The study of physics was intellectually satisfying and scientifically stimulating. Unfortunately, the same was not true for chemicals. Of late, biologists are also stating to use more and more mathematical formulations. Probably natural sciences are getting ready to make quantitative estimate.

The biggest injustice done is to attach a speaker to a Geiger counter, You must remember that nobody attaches a speaker to a gas chromatograph. In case higher values of hazardous chemicals are detected, the speaker howling is more dramatic and will definitely arrest the attention and create a problem.

There are several aspects to the understanding of the risks from chemical compared to the risks from chemical radiation. Natural radiation is present everywhere. There is no such analogue in the case of hazardous chemicals. Releasing genetically modified plants without control is probably in my view a higher problem. No doubt of course, this area getting more attention now.

KSP When the French Academy if Sciences published a report critical of ICRP for lowering dose it as French Government policy. To many, it was not surprising as France has a stake in nuclear power. They feel that lower dose limit is probably not in this interest. What is the current position of the French Government?

RC: The French Government has signed the European Directive. The French Electric Power Industry is committed to ICRP recommendations.

KSP: Release form a nuclear facility can be controlled by appropriate methods. It may cause increase in the collective doses to workers. In some instances the collective doses to workers may be far more than those to public. Which option will be acceptable in your opinion?

RC: Both occupational and public exposures are being reduced by optimization procedures. Storage of waste on-site may actually cause a potential for accidental exposure of the public as well as exposing workers. As long as individual doses – workers and public – are acceptably low, the situation is optimized.

KSP: The recommendation of ICRP are universally respected. I remember that the National Radiological Protection Board recommended a dose limit of 15 mSv/year even before ICRP recommendation were issued. NRPB faced some amount of criticism. What is the status of implementation in the UK and USA?

RC: The European directive was issued in May1996. These directives are legally binding on all states and the directives were to be implemented by 2000. In UK, the Health and Safety Executive has to make appropriate already been started. There is a need for harmonizing different documents. For instance different exemption levels are given under different contexts in Europe.

KSP: why are there such differences in exemption levels in Europe?

RC: In UK, the Radioactive Substances Act is one of the regulations which is different from The lionizing Radiation Regulation 1985. Health and Safety Executive is reviewing both these. The disposal of radioactive substances comes under the Radioactive Substances Act. The harmonizing of values and concepts and making them consistent is taking some time.

KSP: Was it not because there are some differences in opinions and views?

RC: That is not the reason. Certainly different agencies are at work. Most of the values of exemption levels are given in the European Directives.

KSP: Based on the impression that ICRP may revise the dose limits downward, AERB had its first comprehensive review of occupational exposures in 1989, a year before ICRP 60 was issued. We have implemented the recommendations are similar to those of ICRP except that the maximum dose limit in any year recommended by AERB is 30 mSv instead of 50 mSv recommended by ICRP.

Our experience is that among the various groups using ionizing radiation, industrial radiography is the most important. In India this field is probably one of the most regulated. The Regulatory Board issue authorization only if certified radiographers, a site-in-charge and appropriate radiation measuring instruments and protective accessories are available at every site.

RC: Industrial radiography has certain peculiarities. In this field, the workers are likely to be exposed to high radiation doses. The field has more potential for accidental exposures. I understand that ionizing radiation occurred in the field of industrial radiography. A man whose film badges did not record any reading but did due to radiation exposure related symptoms.

KSP: He must have been totally careless. I remember that the dose to this worker was evaluated by very advanced dosimeter method using his teeth as sample. What do you propose to make this field safer?

RC: This field is such that it is impossible to supervise them well, as their place of work is distributed in various work environments. For instance, often they work alone in the field while laying gas pipelines. So the only way we can improve the safety status in by imparting appropriate training to the workers. The regulatory organisation should ensure that such dedicated training programme is extended to all the workers.

KPS: Since reducing dose in medical X-ray practice is easier and less expensive, is it not more appropriate to allocate resources more prudently to achieve substantial reduction in collective doses in diagnostic radiology? If I say that there should be more efforts to reduce needless medical exposures, it may be looked upon as an attempt to divert public opinion from exposures in nuclear installation. ICRP should come out with such clear statements on avoiding needless exposure.

RC: We have gone a long way. The International Basic Safety for Protection against Radiation and safety of Radiation Sources has given certain guidance values. The United Kingdom also accepted certain guidelines. With these precautions, the collective dose can be reduced by about 40% But this was more than offset by the predominant use of CT scan units.

KSP: When many States in the US brought out guidelines for typical X-ray examination based on the National X-ray Trend Programmes, UK was less enthusiastic about the concept. Now Basic Safety Standards came out with guidance. What is your general view on this? Can you include the guidance levels in regulation?

RC: I believe that prescribing guidance levels similar to the one stated in BSS is in the right direction. The experience in the UK has been that there has been substantial reduction in collective doses to population at large over the year.

KSP: In your lecture at the International Conference on Medical Physics you spoke about carrying out appropriate evaluation of dose to commercial airline workers under the category of occupational workers. How many countries in Europe have done this?

RC: Cosmic rays obviously come under natural radiation. Under the European law, the member states shall undertake surveys to estimate the magnitude of the radiation exposure due to natural radiation. Currently large groups of persons journey by commercially operated airlines. Because of this, exposure to sensitive groups such as pregnant women may also have to be considered. There is a general thinking that dose contribution to the crew of commercial airline should be quantified by appropriate methods. This cab be done by on-board instrumentation and by considering the number of hours of flying by the airline. The intention is not that all the crew must wear dosimeters but the measurement of exposure will have to be carried out systematically.

KSP: At such high altitudes, the primary component of cosmic rays are high energy protons and neutrons. This is probably one area where we cannot do much about source control. What we can do is that regulated the exposure and the altitude in which the airline flies. The probability of radiation hitting the embryo or foetus will be miniscule. What is your thinking?

RC: I must say that currently the air crew are not subject to dose limits. But the radiation dose should be measured reasonably accurately by asking the number of hours the crew has flown and also by ascertaining the route of travel.

KSP: I understand that the Concord has appropriate monitoring equipment on board way back in 1970. When I was attending the Congress of international Radiation Protection Association at Brighton, I was at the dinner table with a group of scientist from UK who were actually making measurements in the Concord. Have you carried out systematic measurements? Is there anything new published since the special issue of “Radiation Protection Dosimetry” journal was published?

RC: Yes. Radiation measurements have been done and date are available.

KSP: I thought that the exposure is significant only during solar flares.

RC: According to my information the radiation levels on no occasion has increased to such an extent during the past 20 years which led to reducing the altitude of the aircraft to get the benefit of atmospheric shielding.

KSP: ICRP recommendation on pregnant women is known to be too conservative. What was the background information? Was there any re-thinking on this? As the dose limit recommended is different to measure, many institution may decide to withdraw pregnant women from radiation work. I understand that the topic is widely discussed in countries such as Canada where a great proportion of medical radiation workers are women.

RC: ICRP considers that the basis for the control of occupational exposure of women who are not pregnant is the same as that for men. On the other hand if a women is or may pregnant there is a need for additional controls to be considered to protect the unborn child. The considered is at times more prone than the post-natal individual to deterministic injuries caused by radiation and may be more sensitive to the induction of later deterministic effects in the live-born child including significant mental retardation will not happen if the exposure of the mother dose not exceed the dose limits now recommended for occupation exposure regardless of the distribution of the exposure over time.
Accidental high exposure of the mother may be more damaging to the concepts than to the mother.

The commission’s policy us that the methods of protection at work for women who may be pregnant should provide a standard of protection for any concepts broadly comparable with that provided for members of the general public. The commission considers that its policy will be adequately applied if the mother is exposed prior to the declaration of pregnancy under the system of protection recommended by the commission including the recommended dose limits for occupational exposure. This is the basis on which the commission recommended that no special occupational dose limits is needed for women in general.

The ICRP thought the recommendation of 2 mSv measured over the abdomen of a pregnant woman for the entire gestation period is very helpful. But there is some feeling that it is very restrictive.

KSP: In fact in Canada Atomic Energy Control Board (AECB) arranged discussion with woman workers in eight cities and asked for views. A few hundred women participated. Many of them argued that there is no reason to change the earlier limit of 10mSv.

RC: The Commission no longer recommends a dose limit of 2 mSv during the gestation period as measured on the abdomen of the pregnant women. The ICRP publication number 75 describes the current ICRP recommendation. Overall risks associated with radiation exposure of men and women are broadly similar. ICRP now sees no need to make any distinction between the two sexes in the control of occupational exposure. But once a worked is known to be pregnant, ICRP recommends higher standard of protection for the concepts.

The advice given in publication No.60 has been interpreted too rigidly. ICRP now recommends that the working conditions of a pregnant worker after the declaration of pregnancy, should be such as to make it unlikely that the addition equivalent dose to the concepts will exceed about one mSv during the remainder of the pregnancy.

It is important to highlight the responsibility of the worker and employer to meet the Commission’s objective. The pregnant worker should declare her pregnancy promptly to the management. The management should then organize the working conditions to make it unlikely that the additional equivalent dose to the concepts will exceed about one mSv during the remainder of the pregnancy.

KSP: Atomic Energy Control Board of Canada had detailed consultations with women groups on the reco0mmendation. I understand they may now recommend an external dose limit of 4 mSv on the abdomen or an intake of 20 percent of the annual limit if intake. ACEB had compared the general risks to the foetus during pregnancy and showed that at 4 mSv it is very low indeed. What is your view on this approach? I feel that if ICRP’s view expressed in publication No.75 is accepted, many employers will discriminate against women being employed in radiation work.

RC: The ICRP position is essentially as it was in publication 60 and elaborated in publication 75. The foetus to be protected broadly as though it were a member of the public.

KSP: Though conceptually it is clear that exposure at the dose limit is just tolerable, exposing everyone to the dose limit all the tome is not acceptable. Was it not more appropriate for ICRP to recommend a range of values rather than a single value?

RC: The current dose limit of 20 mSv per year average for 5 years offers this operational flexibility. A single number is administratively convenient. It is obvious that the body dies not known whether the exposure occurred in one calendar year or another. Biology does not identify this.

KSP: The recommendations of ICRP are scientifically the best available. But you will agree with me that these recommendation have enormous social impact. Is it justifiable for over a dozen specialists in purely scientific disciplines to take such decisions which have enormous social impact? Don’t you think that the representation in ICRP should be broadened to include social scientists and economists?

RC: There are various components to this question. ICRP recommendations reflect the best scientific information. We do not say what is acceptable to society or not. There is one recent development. ICRP is currently engaged in more and more consultations with specialists by providing drafts of their recommendations to other specialists and concerned people for review. It would certainly reveal whether there is any inconsistency in the concept and approach put forward by ICRP. It will help to find out whether there is any fallacy in our approach. I believe the recent ICRP document bear testimony to this.

An Interview with Nobel Laureate Professor Roald Hoffmann

2009-08-12T17:36:00.002+05:30

EXTRACT OF THE INTERVIEW GIVEN BY PROFESSOR ROALD HOFFMANN, NOBEL LAUREATE TO DR. K.S. PARTHASARATHY, SECRETARY, AERB ON JANUARY 01, 1998 DURING HIS VISIT TO INDIA TO RECEIVE THE JAWAHARLAL NEHRU BIRTH CENTENARY AWARD AND ATTEND THE 85TH SESSION OF THE INDIAN SCIENCE CONGRESS HELD FROM JANUARY 3 TO 7, 1988 AT HYDERABAD.
(Published earlier in the AERB Newsletter

KSP: Professor Hoffmann, AERB publishes a quarterly newsletter which is sent without charge to universities and institutions carrying our research and development and to individuals. On behalf of the readers of the newsletter I am keen to seek your views on nuclear power and related subjects. I am certain that the readers will value your views.

Hoffmann : In USA, over 100 nuclear power plants are operating. The estimates by the US Nuclear Energy Institute indicate that there is appreciable increase in the capacity factor of nuclear power stations on an average during the past several years. “There is also a claim that these improvements are achieved by the measures taken by the nuclear industry after the accident at the Three Mile Island Nuclear Power station. Still there is a feeling that nuclear power is on the decline in US. Is it true?

Hoffmann- It is true that there is no further growth of nuclear power in USA. Some people mistrust nuclear power. Rightly or wrongly, ,many people perceive that nuclear power production is not under control.

However, I do not think that any of these are the real reasons for the lack of growth of nuclear power. In my view the main reason is economic. The petroleum lobby exerts tremendous pressure. Because of this lobbying the price of petroleum products is unrealistically low.

Nuclear energy cannot compete in the open market in that sort of atmosphere.

The academic community is divided on their views on nuclear power. Most of them know that nuclear power is safe . They also know that the fear of environmental degradation due to nuclear power is misplaced, though they have some concern about nuclear waste management. By and large, scientists are pretty well happy with the environmental aspects of nuclear power, but are not so much aware of the economic aspects.

KSP - You mentioned that there is a notion among public that nuclear industry is not control. In what way this perception can be corrected?

Hoffmamm – People are not aware of the strict training programmes instituted by those who operate nuclear power reactors. They are also not aware of the quality control procedures in place. The nuclear industry should strive hard to publicize the information about these activities.

I feel that in a way the perception problem is somewhat insoluble. Though accidents are very rare, the public concern is genuine, as the risk involved is immense in case an accident occurs. Risk perception is not the same thing as risk assessment.

KSP – Is it true that opposition to nuclear power is partly due to the anti establishment attitude of section of the public?

Hoffman – Yes, there is some truth in it. When people are well off as in some of the European countries they find some new things to worry about.

KSP – It is said that giving public all the information is probably the best way to correct is probably the nest way to correct the imbalance, is that really so? There is also a feeling that giving more information by itself may not help. Though the informed person may be little more informed. It may probably sensitize groups of individuals and also make them more concerned.

Hoffman – I am for a very open system. In this respect, NASA did a very good job. They were very sensitive to public opinion. The public will accept risky activities. If they are told openly of the risks. A very open system is always better I am in favour of talking to people and informing them. This is precisely what NASA did. Still, Space has a romance of its own, not like nuclear power.

KSP –Generally, scientists are not good communicators. Nuclear scientists are not different. Do you have any views on the way scientists should communicate?

Hoffman - Television is a good medium. I feel that there should be good TV programme on basic science.

KSP : The staff of the Atomic Energy Regulatory Board participated in some TV programmes, mainly in form of discussion. Don’t you agree that science programme have great disadvantage?

Hoffman : Well, they cannot obviously compete with entertainments programmes?

KSP – In the Kyoto conference a few pro-nuclear industrial for a promoted the virtues of nuclear power as a clean source of power which doe not emit green house gases. Do you think this approach is appropriate?

Hoff – I feel that the information on environmental advantages of nuclear power is new. the enhanced greenhouse effect due to fuel combustion is established. Exhaust. From automobiles and gas emission from fossil fuel plants are clearly visible. People are used to burning things, so the notion of emission of carbon dioxide is accepted. People relate drought, flood and climatic disasters to green house effect. People can be easily sensitized to issues of climatic changes. So nuclear power protagonists can have a natural alliance with informed environmentalists.

KSP – What do you think are the other concerns of people in regard to nuclear power?

Hoff: Waster management is an important issue. The public is concerned about waster. I am concerned about waster, both industrial and nuclear. Of course, it is the military nuclear waster, accumulated over the past few decades which creates the greatest problem.

There should be a long term programme for waster management. This is one area in USA, where the local, state level influences matter. Not in my Backyard (NIMBY) is currently the prevalent policy.

As for industrial wastes, heavy metal pollution is very important;. Organics and plastics are biodegradable over a period of a few hundreds of years.

KSP:In the case of nuclear waster also, barring some transuranics, the major part of the radioactivity comes from radionuclide such as Cesium-137 and Strontium-90 just as plastics are biodegradable over a few centuries these fission products decay to years. As a matter of fact you will agree that much of the industrial waster including heavy metals remain toxic for ever and as such should belong to a different class of waster materials. For instance, enormous quantities of mercury are released from coal power stations. What do you think is the ultimate solution of radioactive waster management?

Hoff – In may view, vitrification, followed by storage in geological formations is the solution for radioactive waster. One has to find out geological formations where the vitrified waste can be stored indefinitely. There are many, uncertainties in regard to such geological sites.

KSP – Any general comments about nuclear industry in US?

Hoff – I personally believe that we made a mistake in US. We allowed the nuclear industry to go private. People mistrust private industry.

KSP – Is it because of profit motive.

Hoff – Yes, in a way, private industry may cut corners to make profit. I prefer that the operation of nuclear power plants to be totally in public hands.

KSP – Post Three Mile Island and Chernobyl, the regulatory mechanisms got strengthened. Don’t you think that self regulation is better than the imposed regulation?

Hoff – Yes, self regulation has merits, but in my view, there should be separate regulatory control, totally independent, even when the Government operates nuclear power plants. Regulation and control should be separated from operation. I also strongly feel that in regulatory organizations there is a need to involve well informed environmental scientists.

KSP - What is your view about the renewable sources of power?

Hoff – I am convinced that renewable have vital role to play. Hundred years from now petroleum will be exhausted. Eventually we will have to come back to solar and nuclear energy sources. They are cleaner. Solar is already used significantly in passive heating. There is also scope for large area solar energy collectors. Solar photo-voltaic technology developments in electronics are related. In my opinion solar energy development will unplanned fringe benefit of the development of electronics industry.

KSP – Do you agree that the renewable excluding hydropower are unlikely to make a significant contribution to electric power generation due to various reasons?

Hoff – Solar is already making its contribution in small ways, say for instance, passive methods, hot water heaters, solar calculators. Solar power is currently expensive. But I believe that in a few years from now solar and nuclear will become competitive.

KSP – Professor Hoffmann, I am very grateful to you for sparing your valuable time for this informative interview. Is it your first visits to India?

Hoff – No. I has been here three times earlier. In one of my visits I was at the Ciba Geigy Laboratories. My only regret is that I could not see much of Bombay this time.