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)

Lessons to belearnt from Delhi radiation incident

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

Published on: August 28, 2010 - 23:04

More in:

• Panorama

By Dr KS Parthasarathy
On August 6, 2010, Hiroshima observed the 65 anniversary of the atom bombing. The anniversary of Nagasaki bombing was on August 9. For the first time, United States sent an envoy to Hiroshima.
The US ambassador to Japan, Mr John Roos, laid a wreath ‘to express respect for all of the victims of World Ward II’. Britain and France, its World War II allies sent their first diplomats to the ceremony, indicating support for the goal of nuclear disarmament. Mr Ban Ki-moon, the United Nations Secretary General is the first UN Chief to attend the function. Everyone wants to draw attention to the urgent need to achieve global nuclear disarmament.
In the hurry and excitement of global politics we may forget the priceless research on biomedical effects of radiation carried out by the Atomic Bomb Casualty Commission and its successor Radiation Effects Research Foundation (RERF) which was set up in 1975.
From the 280,000 survivors in the two cities, the RERF scientists established fixed cohorts or cohorts to provide epidemiological and clinical data on the health status and mortality of survivors and their children. The latest issue of RERF update, a publication from RERF, noted that RERF and ABCC scientists have been evaluating, documenting and publishing for the past 63 years, the long-term health effects associated with the ionising radiations emitted by the A-bombs in Hiroshima and Nagasaki.
"Much of the research of ABCC, and now RERF, has focused upon characterisation of the effects of the A-bomb radiation exposure on the immunological parameters in the survivors. Those studies are being conducted in an aging population in one of the longest-living and most homogeneous population in the world." (RERF update, 2010).
The US National Institute of Allergy and Infectious Diseases (NIAID) is funding the project. RERF researchers will be able to define the effects of ionising radiation on aging of the human immune system and elucidate the underlying mechanism.
The project is possible because they can use the large, unique data base and bio-samples from the 63-year follow up of A-bomb survivors. Co-investigators from five US and Japanese institutions will provide their expertise and methodologies for the success of the project.
The main focus of the project is immunosenescence, the gradual deterioration of the immune system with aging. The process involves many vital activities. The host’s ability to respond to infections may degrade; the development and retention of long term immune memory including the one generated by vaccination may diminish; the immune cell turnover may alter and an imbalance between the innate and adaptive immunity may potentially cause enhanced and persistent inflammatory responses.
When successfully concluded the studies may lay a foundation to explain some of the long term health effects observed in A-bomb survivors.
There is clear evidence for excess leukaemia and solid cancers among the exposed population. These observations helped the International Commission on Radiological Protection to recommend dose limits to workers and members of the public.
Recently researchers noted an increase is non cancer-diseases among the survivors. They can explain this only if their understanding of the defects in the individuals’ immunological system over time and with prior radiation exposure improves. They hope that such studies will provide a solid, scientifically grounded basis for risk assessment, regardless of the disease outcome of interest (RERF Update, 2010).
"It will open opportunities for prophylaxis, prevention and treatment of the resulting disorders", the researchers concluded. The latest RERF update summarised thirteen areas of research. RERF and its collaborating subcontractors will conduct four projects for elucidating the effects of ionizing radiation and aging on blood-derived stem cells, dendritic cells and their precursors (these are crucial in triggering immune response against infections) and on vaccination responses. The plan to develop an integrated scoring system for human immune competence as it relates to aging and ionising radiation.
The Departments of Clinical Studies in Hiroshima and Nagasaki have been carrying out Adult Health Study (AHS) for over 50 years. Summarising the work of these departments, Fuliwara and Akahoshi clarified that the objective of AHS is to determine radiation risks for diseases that cannot be documented adequately by the larger mortality study called Life Span Study (LSS) (RERF Update, 2010).
These studies include the effects of radiation on the risk of non fatal heart disease or stroke, high blood pressure, various benign tumours and other adverse health effects.
About 20,000 subjects in the AHS group have provided biological samples once every two years from 1958. The repeated samples proved invaluable as they are seldom available in any other project anywhere in the world.
RERF is carrying out a comprehensive study (F1 Clinical Study) on nearly 12,000 children of A-bomb survivors. It evaluates the possible association between radiation exposures of their parents and the frequency of diseases such as heart disease, stroke, hypertension and diabetes. Now their average age is 50; they have developed little disease thus far and there is scope for long term study.
From 1978, AHS group included 2000 additional high dose groups and nearly 1,000 (all available) persons who were exposed to A-bomb radiation while they were in their mother’s womb.
The relationships between exposure to radiation and non cancer -diseases were not expected. Recently, researchers discovered that radiation is associated with premature menopause. This may cause earlier onset of increase in cholesterol levels and cardiovascular disease.
RERF researchers are studying liver stiffness, chronic kidney disease and cardiovascular disease and their possible relationship with radiation exposure.
The clinical evaluation of nearly 12,000 children of A-bomb survivors provided no evidence of an increased prevalence of multi-factorial diseases in relation to their parental exposure.
RERF scientists noted that the prevalence of cataract increased with radiation dose with a dose-effect threshold that was much lower than previously believed.
RERF is continuing with intensive and extensive studies on human diseases’ with unparalleled resources at its command. Spin offs from these may help fight gruesome diseases. This may be the notable contribution from the dastardly event which occurred over six decades ago. PTI

Cataract risk for unprotected interventional cardiology personnel

  

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

                                            

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

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

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

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

Date:10/06/2010 URL: http://www.thehindu.com/thehindu/seta/2010/06/10/stories/2010061050631600.htm
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Back Sci Tech



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

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)