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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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 )
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