Lessons from History of Radiation use and
Nuclear Accidents particularly Fukushima
Department of Physics
Cambridge, 02138, MA
To be Presented at 44th seminar on Planetary Emergencies
World Federation of Scientists
August 20th 2011
Ettore Majorana Center
The importance of understanding radiation issues
for immediate analysis and immediate action.
Effects on Public Health
I will focus on the public health aspect of the Japanese, and indeed the world, reaction to the Fukushima crisis. Firstly I will summarize those facts that I consider to be important and explain why I believe the reaction was incorrect.
Medical use of X rays.
Very soon after Roentgen’s discovery of X rays in 1895, physicians used them for diagnostic purposes. Although very early it was realized that they caused skin and other lesions the fantastic ability to see within the body was so important that physicians correctly argued that the benefits of the X ray use overshadowed any harm. But this only addressed one part of the risk-benefit calculation. Others, physicists in particular, pointed out that the same benefit could be achieved with far less harm by more careful use. Shielding. More sensitive film and so forth.
In the 1920s there was more interest in controlling the use. In 1927 the International Commission on Radiological Protection (ICRP) was formed. This is a non governmental body but most governments heed its recommendations. But the advice of ICRP and physicists was not fully heeded till about 1970. In l961 for example I had an (unnecessary) chest X ray at Stanford University and measured my dose. About 1 Rem. Now the same X ray would take 7 mRem. But a CAT scan today is nearly 1 Rem.
Hiroshima and Nagasaki
Starting in August 1945 physicists have been involved with extensive nuclear activities. Although there is a common public misconception that 200,000 persons each died because of radiation exposure at Hiroshima and Nagasaki, most of the deaths were due to blast and radiation accounted for only a few percent. Nonetheless an unprecedented research activity took place. The Atomic Bomb Casualty Commission (ABCC) (now the Radiation Effects Research Foundation - RERF) was jointly funded by USA and Japanese governments to study radiation effects. The UN started the United Nations Subcommittee on the Effects of Atomic Radiation (UNSCEAR) which lists over 100,000 reports and papers on the subject. Also the US National Academy of Sciences has issued a useful set of reports Biological Effects of Ionizing Radiation which are more readable.
Distinction between Acute problems and Chronic problems
The studies find a crucial distinction between the results of radiation exposure in a short period (integrated over a week or two) and the acute effects that it causes, and radiation over a long period of a few years and the chronic effects that causes. The acute effect of Acute Radiation Sickness starts with a reduction in white blood cell counts and can then lead to tissue damage. It is generally accepted that this occurs at radiation levels above 100 Rems (1 Sv) with an LD50 (least dose at which 50% of people die) if 250 Rems which can be extended to 350 Rems by a blood transfusion. The first major example of a death from Acute Radiation Sickness was Dr Louis Slotin who died of Acute Radiation Sickness in May 1946 as a result of a nuclear criticality accident. It is not always realized but prompt evacuation is only needed to avoid Acute Radiation Sickness.
Hiroshima and Nagasaki provide the data from which effects of radiation are usually determined. As occurs with all chronic effects, they are determined at a high radiation level and a model is used to describe what happens at the lower level. At low levels the usual model suggests low dose linearity. This comes from the realization that if a medical outcome of a pollutant or action is indistinguishable from one that occurs naturally, any addition to natural incidence is proportional to the dose at low doses.
Crump KS, Hoel DG, Langley CH, Peto R. 1976. Fundamental carcinogenic processes and their implications for low dose risk assessment. Cancer Res 36:2973-2979.
Guess, H., Crump, K., and R. Peto. 1977. Uncertainty estimates for low-dose-rate extrapolation of animal carcinogenicity data. Cancer Res. 37:3475-3483..
But there are assumptions and approximations. In the above sentence I used the word “indistinguishable”. They must be biologically indistinguishable and not merely that a pathologist cannot distinguish. Alas I know of no one looking at this fundamental point. The coefficient of the linear term is determined from data at high doses. Also the dose in Hiroshima and Nagasaki was over a short period and it is probable that doses over a long period produce smaller effects. There are animal studies that suggest a factor of 2-10 but only two data sets. The occupational doses at Ozerk in 1948 as the Russians were rushing to make a bomb before the wicked Americans killed them, and the Russians exposed at Techa River after the waste pond overflowed.
According to the above theoretical model, if someone gets a dose just below the LD50 he can still get chronic problems of which the most important is cancer. At an integrated dose of 200 Rems there is a 10% to 20% increase in cancer probability. This depends upon a dose integrated over a long time - of the order of years. It can therefore rise well above 200 Rems without causing Acute Radiation Sickness. The natural incidence of fatal cancers is about 10% so no one who gets less than 100 Rems will double his natural incidence and he cannot rightly claim that it is “more likely than not” that his cancer is due to radiation. These numbers are deliberately a little higher than my best belief at the moment and do not account for a dose rate reduction, but they are at the upper end (more pessimistic) of the fraction in the most recent US National Academy Report BEIR VII Table 1. At 100 millSievert, 0.1 Sv or 10 remas the increase in fatal cancer probability is 4% or 20% of the natural fatal cancer rate.
The radionuclides that are produced by nuclear fission are well known, as are their melting points and boiling points. A listing can be found, for example in Table B3 of the report of a study Severe Accidents at Nuclear Power Plants that was carried out for the American Physical Society and is on this website at http://phys4.harvard.edu/~wilson/publications/pp341.pdf and Reviews of Modern Physics, 57, 3, pt. II, July 1985.
I call attention to the isotopes of iodine and of cesium the former is normally gaseous and is easily released and the later, although normally solid, is soon evaporated in an accident. Only in an explosion would it be likely to emit large quantities of strontium, uranium or plutonium.
Nuclear Power - normal operation
Physicists and engineers have been urging careful use of radioactive materials. A modern nuclear power station emits very little radioactivity. Indeed it is often stated (correctly) that a coal fired power station in its particulate emissions emits more. Also the exposure to the plant workers can be kept low without sacrificing performance. They (as health physicists) have set standards which are low and can be met with little cost. The benefit of a low radiation exposure is not limited by a high cost to the consumer of electricity.
But when the situation in a power plant is not normal all changes. The habits, rules, customs about radiation exposure should change accordingly and the change should be automatic and instantaneous and therefore prepared in advance. This did not happen at Fukushima. The need to balance risks is similar to the physicians’ situation in 1900-1970.
Windscale, TMI and Chernobyl
There were three reactor accidents from which lessons can be learned.
At Windscale in 1957 a plutonium production reactor caught fire and iodine was released. Short lived radioactive iodine (I 131 with 10 day half life) can make the major immediate hazard with a well known chain. Iodine can fall to the ground and be eaten by cows where it concentrates in the milk and babies drink the milk and concentrate the iodine in the thyroid. This has been realized for 60 years and at the Windscale accident in the UK in 1957 the government impounded and bought all milk for a couple of months. (Curiously the cows produced twice as much as usual, although this increase is not usually attributed to radiation!)
No one knows exactly how much iodine was ingested at Chernobyl, but a lot. 2,000 children got thyroid cancer of which 20 have died. No one need have got thyroid cancer if it were not for secrecy. There are anecdotes (which I believe) that a school teacher near Hohnichi (Belarus) and an Army general in eastern Ukraine were reprimanded by the KGB for advising children not to drink milk for a month (the half life of the iodine is 10 days or so) and thereby causing a panic. This was, and is, far less likely to happen in an open society in Japan.
There is disagreement about the effects of potassium iodide. If ingested before radioactive iodine exposure it can reduce the ingestion of the radioactive substance. But there are suggestions that if taken after exposure to radioactive iodine it can lock in the radioactive iodine already taken. Moreover, there are other side effects particularly for pregnant women so it is wise not to take it unnecessarily.
At TMI in 1979 there was a partial meltdown but mostly contained. I can find no report of what happened to the iodine, but believe that it combined with water to form HI which was pumped out of the containment into the turbine building where it stayed quietly on the floor.
After Chernobyl in 1986 we confirmed that the important releases for the long term effects are Cesium 134 (2 year half life) and cesium 137 (30 year half life), and that the radiation from the ground deposition is the important pathway with ingestion only about 25%. Evacuation from Pripyat was delayed 36 hours and Chistallogovka 3-4 days. But prompter evacuation would not have changed the dose much. Only at Chernobyl did anyone in the plant get Acute Radiation Sickness. No one in the general public did. .
In the preceding paragraphs I note that exposure to Cs 134 and Cs 137 is the dominant long term problems. The measurements of radioactivity deposition confirms that deposition and therefore emission of strontium 90 and the transuranic elements was much less, even though the initial explosion dispersed them locally, and the subsequent graphite fire must have reached thousands of degrees and almost all the cesium was evaporated. That is an important observation because strontium and plutonium in particular are “bone seekers” as they enter the body giving long term irradiation to various organs. .
One important feature is that the effects on health of these low levels of radioactivity are calculated, not measured. They are too small to be directly measured. Those who wish to dramatize the effect tend to stress the total number of calculated fatal cancers. Typical numbers discussed are 4,000 -8000 in the USSR countries (Ukraine, Belarus and European Russia) and 20,000 world wide. The latter is to be compared with the billion or so naturally occurring cancers in the world in that time period. But for discussions of how to manage an accident more direct information is appropriate.
Armed with this information I looked at the measurements from Fukushima-daiichi. I looked at the data on the radiation spike measured at the gate of the Fukushima complex and integrated it. .
(The particular figure 1 comes from a German website)
The releases on Friday, Saturday, Sunday and Monday were not serious. The big doses were on Tuesday March 15th and Wednesday March 16th. The spikes were probably doses from noble gases. The integrated dose was large, 0.02 Sv (or 2 Rems). But this is less than 1 year of normal occupational dose and it should not have prevented a radiation worker from going to or being near the plant. Indeed the report to IAEA states that the average for all power plant workers as of May 23rd was only 7.7 mSv or 770 mRems. About the amount of a CAT scan.
Starting on Thursday March 16th the
reactors and the spent fuel pools were being cooled by sea
water, and there has been no comparable release since that
time. Taking the usual decay of Cs 134 and 137 into account
one would expect an immediate drop, and my estimate would be
for about 0.06 Sv (6 Rems) at the main gate for the first year
and falling more slowly thereafter. At 3 miles (5 Km) this
would be down a factor of 10.
Adverse effects on health of dislocation/evacuation
It has been noted in the medical community for many years that there are stresses and problems associated with relocation that can lead by themselves to adverse effects on public health. In 1975 I saw figures of a 5% increase in cancer probability. I note that in an accident situation this would only be a calculated increase but in that sense is directly comparable to any increase in cancer rate due to radiation. It is hard to find good numbers and refer to a recent review:
Health effects of relocation following disaster: a systematic review of the literature. By Uscher-Pines L. Disasters. 2009 Mar;33(1):1-22. They opine:
Despite the frequency of post-disaster relocation and evidence of its effect on psychological morbidity, there is a relative paucity of studies; the few examples in the literature reveal weak study designs, inconsistent results, and inattention to physical health impacts and the challenges facing vulnerable populations. Further research guided by theory is needed to inform emergency preparedness and recovery policy
.In the 1980s Dr Crouch and I looked at the unexposed “control” rats and mice from the US National Toxicology program. The rate of cancer varied many percent. For example we found that in some experiments the lights in the cages were on continuously and these were rodents with an elevated “control;” rate. In the large study of 30,000 mice at the National Center for Toxicological Research (NCTR), the ED01 or “megamouse” study there was a variation in response according to where the cages were. Those on the top shelf got tumors later than those on lower shelves. I presume that is because their stress was less. But what counts as stress for a mouse is unclear.
I take 5% increase in cancer probability from relocation as a good guess.
The "official" Kemeny report after the Three Mile Island accident stated (inter alia) "We conclude that the most serious health effect of the accident (for any reason) was severe mental stress, which was short-lived. The highest levels of distress were found among those living within 5 miles of TMI and in families with preschool children. "
Japanese have noted unexpected deaths in the elderly who have been evacuated. Significant numbers of the elderly in shelters have died unexpectedly. Maybe the calorie intake is below starvation level and not all have three meals a day. Lack of hot food, running water, crowding, poor toilet facilities and lack of water for cleaning people and locations, lack of fuel and lack of hospitals to accept admissions, ambulances or medical services except what appear to be medical personnel who are themselves local victims. Yet there is no indication that these were considered by those ordering an evacuation! A simple calculation shows that this can far exceed any benefit evacuation may bring.
I first looked at doses in various locations listed by the Japanese Atomic Industrial Forum. http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1302054182P.pdf (Figure 2)
Indeed the newspapers emphasized the doses in the Ibaraki region, on the way to Tokyo. The abscissa is microSievert per hour. But the dose seems much smaller when the doses in the Ibaraki prefecture are plotted with a different abscissa and ordinate. (figure 3)
One microSievert per hour, kept up for a year, would give 8760 microSievert, or 8.76 milliSv or 876 milliRems. What does this mean?
Many actions can give anyone a dose of 876 milliRems:
A single chest x ray in a major hospital as late as 1960.
A CAT scan today.
7 months allowable occupational dose
1/25 of what a Chernobyl clean up worker got
1/100 of an astronaut's allowed dose.
About the dose I got in 1991 from a day at Chernobyl mostly inside the sarcophagus
Any serious student should evaluate his own lifetime dose for comparison. I have been officially a “radiation worker” since 1946. Yet my integrated dose is almost all due to medical X rays – and I have no record of these for the first 20 years. The American Nuclear Society has a website which enables a good estimate to be made on line: Radiation Dose Chart: http://www.new.ans.org/pi/resources/dosechart/
There is no indication of any large deposition of either strontium or transuranic elements, suggesting that the internal deposition by these elements can be ignored.
Shows a radiation map of the area NW of the plant, in April 2011.
From this MEXT use a theory to estimate the integrated dose to March 2011 shown in Table 2.
The evacuation decision
The question the Japanese faced was how much to evacuate. I believe they flubbed. They had not thought in advance. Then they panicked. It is unclear whether the evacuation was ordered by the government or merely suggested. But it was without analysis. But this is clearly forgivable given the history of radiation effects in Japan and the failure of the world community to provide guidance. Indeed for 30 years the world community has set guidelines which, I argue, are stupid.
They should have asked the questions:
Is there an immediate reason to evacuate to avoid Acute Radiation Sickness? The measured doses give the answer NO.
Would there be an appreciable increase in long term radiation dose by waiting a few days to analyze? Again the realization that Cesium was the problem would demand the answer NO.
In retrospect was it sensible to evacuate people beyond 3 miles from the reactor, bearing in mind the competitive risks? I submit that here again the answer is NO.
Would it have been wise to inform everyone and prepare for a VOLUNTARY evacuation for those who wished it, which preparation could avoid the chaos that occurred in New Orleans after Katrina? Here the answer is definitely YES.
Is there an adverse effect on health in evacuation? Here the answer is definitely YES although often ignored.
I submit that the whole world nuclear power and safety community, including semi-political agencies like IAEA and politicians themselves should ponder the above.
America friends of the Japanese people should ask themselves the following questions:
What is the role of friends who believe they are experts?
Careful analysis along the lines of the early part of this report?
Off the cuff remarks at a Senate budget hearing?
Dr Gregory Jaczko, Chairman of the Nuclear Regulatory Commission gave the following testimony Jaczko to the US Congress on March 17th 2011:
“Recently, the NRC made a recommendation that based upon the available information that we have , that for a comparable situation in the United States, we would recommend an evacuation to a much larger radius than has been currently been provided in Japan. As a result of this recommendation, the ambassador in Japan has issued a statement to American citizens that we believe it is appropriate to evacuate to a larger distance up to approximately 50 miles.”
This was repeated by President Obama, on Thursday, March 17, 2011
President Obama made remarks from the White House Rose Garden on the nuclear crisis in Japan shortly after paying an unannounced visit to the Japanese Embassy. After expressing condolences to the Japanese people, the president confirmed calling for an evacuation of U.S. citizens within a 50 mile radius of the reactors in northeastern Japan.
These were outlandish and not the remarks of a true friend. In my carefully considered view, Dr Jaczko and president Obama should visit Japan and apologize to the Japanese people. Perhaps by bowing deeply to the Japanese legislature. This would be politically difficult for President Obama in his present travails but may be possible the day after the 2012 election- whichever way the decision goes.
I have been told that Jacsko was merely following an NRC rule: keep the dose less than 500 mRem in the immediate accident and < 2 Rem over the first year. I argue that the events at Fyukushima demonstrate clearly how stupid, and counterproductive to public health, that rule is, and it becomes a matter of urgency to modify it.
I note that in an emergency someone has to be empowered to act without waiting for a Commission, or committee meeting. Chairman Jacsko claimed, and still claims, that power. But it was never an emergency in the USA, and it is certainly now over. His outlandish recommendations on Thursday March 17th suggests that he is not capable of exercising that power wisely.
Radiation Accident Management
At Fukushima there was no proper management of radiation doses immediately the reactor situation was out of control (immediately after the tsunami). There seems to have been no realization in Japan, and probably no realization anywhere else, of the fact that radiation management after an accident should, even must, must differ from radiation management immediately before the accident.
Before TMI (before 1980) it was generally accepted that there were certain radiation levels that should not be exceeded. After TMI, and even more after Chernobyl these were reduced. While it makes some sense to keep, for example, to 5 Rems/yr (05 Sv/yr) for a nuclear power worker in ordinary operation it is, I believe desirable to return to he higher figures as soon as an accident goes beyond normal operation. Thus it should be allowed for a worker to plan for 20 Rems (0.2 Sv) for the whole accident, and indeed at Chernobyl 100,000 or more workers got this dose of 20 Rems as "liquidators" (clean up workers). A one time dose of 80 Rems (0.8 Sv) was allowed for an astronaut and for a rare individual "to save lives" 80 Rems was allowed. It is reported that at Fukushima workers were pulled off the job in Sunday and Monday in the Fukushima accident before the Japanese belatedly restored the pre-1980 levels. This probably delayed a proper technical response to the accident. Although at all ages it is important to keep the radiation dose below that giving Acute Radiation Sickness, full use of older workers, particularly volunteers, should be taken. A person over 70 years old with a high accumulated radiation dose will develop cancer only after 20 years and then it is the least of his worries.
It is unclear whether my recommendation of an immediate reversion to the pre-1980 radiation levels would have enabled TEPCO to control the reactors any better. I think they would.
A lesser issue: responsibility of the media.
News media have been the principal method of communicating with the public, and even with experts. At Three Mile Island, at Chernobyl and at the Tokai incident the US media failed miserably and forgot their duty. The internet has improved this. Experts can find information directly. But there is still a responsibility to inform the public, and in particular to explain what the radiation dose levels mean, in terms of public health and to discuss the harrowing decisions those on the spot must make.
I next turn to accident prevention.
The aim is to prevent the undesirable fission products ever coming into contact with the public. There are several barrier:
(1) The fuel is in zirconium pellets with are in a zirconium tube. Although design criteria allowed 0.1% of these tubes to leak, probably none did.
(2) If the first barrier fails, there is a pressure vessel which should hold them.
(3) If the pressure vessel fails there is a containment vessel.
One must emphasize the importance of keeping barrier 1 intact if possible. Of course it is always important to stop an untoward event as early in the chain as possible. But it is especially important because failure here makes it harder to control. In a BWR one can be close to the reactor in operation as I personally have been - one is shielded by the water in the pressure vessel. Once barrier 1 fails, doses are higher outside the pressure vessel increasing radiation doses for a worker and making subsequent fixes harder.
Man Rems (Person-Sievert) or Rems/man (Sv/Person)?
In the preceding paragraphs I have emphasized the dose per person (Rems/man or Sv per person) because that matches the decisions that I was discussing. But in radiation protection it is common to calculate the collective dose 9in Man-Rems or Person Sieverts) because when using a linear dose response relationship and multiplying by the appropriate slope (coefficient) this gives the total societal impact. I do this for the next section on comparing disasters and also take a more optimistic slope allowing for a dose rate reduction factor.
Comparison to other world disasters
The effects of evacuation or not evacuating should be compared to 15,000 dead, and 15,000 missing direct, measurable and definite "dead bodies" from other earthquake and tsunami problems
Fatal cancers calculated from Natural Background (including medical) exposures
(world wide ) about 10,000,000 per year
In an average ½ lifetime 500,000,000
Estimated Deaths from arsenic in Bangladesh
Earthquake in Haiti
Earthquake and Tsunami in Japan (prompt deaths)
Fatal cancers from Chernobyl in next 60 years (calculated excluding effects of stress)
7,500 in Belarus, Russia and Ukraine
Cancer fatalities from Three Mile Island
0.7 calculated for the Kemeny Commission
My prediction: 200 calculated cancers from radiation from Fukushima (originally my prediction was close to zero)
0-5,000 adverse health effects of evacuation.
My recommendations for study of radiation emergencies.
I have argues since 1980 that there should be detailed study of a number of fundamental issues. (These should be for other pollutant substances and actions also)
(1) Are cancers caused by radiation truly indistinguishable from naturally occurring cancers? Or is it just that a pathologist cannot distinguish? (use DNA analysis)
(2) What is the effect of dose rate? (look carefully at such data as the Techa River)
(3) what is the effect of disaster stress on cancer? In people? in animals?
Before 1980 the US Nuclear Regulatory Commission asked for an "Emergency Planning Zone" (not an evacuation zone) of 10 miles diameter. After TMI this became an "evacuation zone" without the detailed discussion such a decision requires. I, personally, was opposed to this implication for automatic evacuation, and testified to an Ontario Royal Commission and others that it was a mistake. I strongly urge the International Community to reexamine this requirement.
My Recommendations for continued nuclear power
There have been already several discussions on what to do about existing nuclear power plants, and proposals for new ones throughout the world. These include recent fine articles in the Bulletin of Atomic Scientists. Many of these discussions echo previous views expressed by the authors asking that certain issues already decided be reconsidered. I here make my comments on several of them: I do not give the detailed discussion that each topic deserves.
(1) We should obviously reexamine every existing nuclear power plant to see whether and how whether any specific problem raised by Fukushima can be easily addressed. We must remember that when the first event tree analysis was done in 1976 it was found that the reactor (Surry) could be made 5 times safer at small expense by modification of a control system. I agree with the Japanese report to IAEA that even extreme events such as a combined earthquake, tsunami and bureaucratic muddle should be analyzed by event tree analysis.
(2) Since it is claimed, and probably true, that newer designs of reactors would be safer and would have survived the terrible events, should we not retrofit all older reactors? And in particular all 23 older GE reactors in the USA? This question has been repeatedly raised over the last 30 years. I believe the question is posed too narrowly. It is too restricted to nuclear plants. Should we not retrofit or get rid of all older energy plants? The cost of retrofits can be high and in many cases would close the plants down. Once the question is broadened we might decide to retrofit, and perhaps close, plants in order of the estimated risk to public health. For example start by closing every coal fired power plant and only then consider the older nuclear ones.
(3) One of the largest risks we face in the world is the risk of starting a catastrophic all out nuclear war. We must remember that while bombs with 100 pounds of TNT killed people in World War II that Sakharov's test explosion at Nuovo Zembla over 40 years ago was of a bomb. ONE BILLION times more powerful. Should we not consider this carefully in all applications of nuclear energy? In particular should that not be a fundamental question asked by the Nuclear Regulatory Commission? While it is evident to me that this issue MUST be in the front of all our minds from now to eternity, it is far less clear that the Nuclear Regulatory Commission is the proper place. Already, as noted above, they have internal conflicts between discussion of "ordinary" operation, and reaction to an accident mode which has resulted in the silly statements mentioned earlier. It goes far beyond Fukushima or indeed beyond any other public safety or public safety issue. Where, when and how proliferation questions should be discussed is perhaps the most important long term issue. Maybe I should invert the question. When are the few occasions when non-proliferation need NOT be discussed? It has been urgent for at least the last 60 years.