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

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

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

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?

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

                                                                      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

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)

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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

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

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)

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

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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

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)