Statement by Scientists and Engineers Concerning Fukushima Daiichi Nuclear Power Plant (no.2)
April 7, 2011
Our Views of the Accidents at the Fukushima Nuclear Plants after the Earthquake
From: The Group of Concerned Scientists and Engineers Calling for the Closure of the Kashiwazaki-Kariwa Nuclear Power Plant
Toda Building, 4th Floor, 1-21 Yotsuya, Shinjuku, Tokyo 160-0004
More than three weeks have elapsed since a powerful earthquake hit the eastern region of Japan. The crisis of the Fukushima Daiichi Nuclear Power Plants continues, and we have yet to see light at the end of the long tunnel. Even if we manage to avoid the worst case scenario in which any of the pressure vessels and the containment vessels are severely damaged that would have allowed for an explosive outflow of radioactive materials in a large quantity, it is certain that the radioactive leakage will last for a long time to come. The atmosphere, water, and soil around the nuclear plant have already been contaminated in the vicinity of the nuclear facilities, and contamination around the nuclear plants will continue. Indeed we must not let our attention drift away from this dismal picture.
In the meantime, it has been reported that those workers who have struggled to contain this disaster at the nuclear plant have been exposed to massive doses of radiation, and that a large amount of water containing a high concentration of radioactivity has been released to contaminate the nearby ocean waters. Agricultural, dairy and marine products have been contaminated by radioactivity, and, it is reported daily in the mass media that, even in cases where the actual degree of contamination is negligible, some of the produce from the region has lost market value as merchandise. Consequently an increasing number of farmers and fishermen have lost their livelihoods and now face hardship. We are once again reminded of how big a menace to people's lives a nuclear accident can be.
For a long time, our group and many other citizens critical of nuclear energy have been warning that a large earthquake and tsunami would result in such a disaster. Nevertheless, the government, electric power corporations, and academics collaborating with the state-corporate complex have gone on spreading their irresponsible propaganda: "nuclear power plants are absolutely safe" and "Nuclear energy is a clean energy source free of CO2 emissions." The adversity many of us find ourselves faced with today is a consequence of their irresponsible maneuvers.
In what follows, we present our view of what is happening at the Fukushima Nuclear Power Plants as well as what must be done to deal with this disaster. (Our group published its view on 23 March 2011. The first statement should be read together with this second statement.)
1. What is the Current Status of the Fukushima Daiichi Nuclear Power Plants?
The accident revealed new aspects, and no short-term solution is in sight. No prospect for remedy has been offered, although nearly one month has elapsed since the earthquake.
1-1. Workers' high radiation exposure in the basement of the turbine building.
While laying electric cables in the basement of the turbine building attached to Unit 3 in the Fukushima Daiichi Nuclear Plant on March 24, three workers stepped in water containing a high concentration of radioactivity and received a whole-body exposure of 180 mSv. It is estimated that the radiation exposure level on their legs was between 2 and 6 Sv. As we will explain below, it was known at the time that highly radioactive water was leaking from the pressure vessel into the containment vessel. We are outraged that no precaution was taken to protect these workers working in such a dangerous environment. In addition, it has been reported that the workers were not equipped with any radiation measurement instruments while working under extremely severe conditions. This is a violation of the nuclear safety law. Granted that it was an emergency situation, nonetheless it was the clear duty of the employer to first secure the safety and health of the employees.
1-2. Damage to the Pressure Vessel inside Unit 3.
Contaminated water found in the basement of the turbine building attached to Unit 3 showed a high level of radioactivity, namely, 3,900,000 Bq/cc. Furthermore, since it contained much Iodine 131, whose half-life is 8 days, it seems certain that it did not leak from the storage pool for the spent fuel rods. It must have come from within the reactor, containing much nuclear fission by-products (same material as so-called nuclear fallout). On March 28th , radioactivity at a level of 3,800,000 Bq/cc was detected in the basement of the turbine building attached to Unit 1. In Unit 2, contaminated water, whose radiation intensity was higher than 1 Sv/h just above the water surface - a contamination strong enough to cause acute disorders within ten minutes of exposure - was discovered. All these observations indicate that, in all three units of the nuclear plant in operation at the time of the earthquake, fuel rods inside the pressure vessels were damaged and had melted, and that pressure vessel water containing nuclear fission by-products from fuel rods leaked outside the containment vessel. This is indeed a very serious situation.
The Nuclear and Industrial Safety Agency first announced that a high concentration (2,900,000,000 Bq/cc) of Iodine 134 was detected in residue water in Unit 2, but the agency annulled the announcement afterwards. The half-life of Iodine 134 is only 53 minutes, and the presence of Iodine 134 at such a high concentration would mean that the core of fuel rods had gone critical as the nuclear fission process restarted. What is astonishing is that the information of such vital importance was released before its significance was considered and the measurement error examined. It was first disclosed by the Tokyo Electric Power Company and then announced by the Nuclear and Industrial Safety Agency. What is striking in this incident is the system of irresponsibility that nurtures such a lack of scientific and professional judgment.
The figures disclosed by the Tokyo Electric Power Company for the temperature, the pressure, and the water temperature within the reactor suggest either that the pressure vessel inside the reactor is broken somewhere or that piping connected to the pressure vessel is broken. From March 20th until March 23rd, the thermometer (thermocouple) on the outer wall of the bottom part of the pressure vessel in Unit 1 indicated a maximum temperature of 400 C?. From the 19th through the 20th, the highest temperature in Unit 3 was recorded at 350 C?. However, the pressure inside the reactor indicated three or four atmospheres, much lower than the equilibrium pressure of water. This means that there was no water left inside the reactor. Later the thermometer's reading fell to between 110 C? and 140 C?, suggesting that the injected water had began to accumulate at the bottom of the reactor. According to TEPCO's measurements , the water level was lower than the middle of the fuel rods, which are four meters long. Assuming that the fuel rods have not been deformed, more than half of their length must be exposed above the cooling water. This explains why the temperature at the upper water supply nozzle remains quite high, because of radiant rays from the fuel rods.
1-3. The loss of Containment Function of the Containment Vessel.
The leakage of contaminated water with a high concentration of radioactivity in the basement of the turbine building suggests that the containment vessel has been damaged. The containment vessel is installed as the last resort, to prevent radioactivity from escaping from the vessel during a grave accident like the current one.
The presence of highly contaminated water suggests one of the following two scenarios. First: in the reactor molten fuel reached the bottom of the pressure vessel where holes for control rods and measurement instruments are located. The holes are sealed with weld metal (nickel alloy), but this weld metal might have reacted with molten fuel and melted itself. Contaminated water could have escaped through these holes to the outside of the containment vessel. Second: the piping of the pressure vessel might have been damaged allowing contaminated water to leak from the broken pipes. The fact that contaminated water leaked from the containment vessel is indeed a serious problem. It indicates that the fundamental function of containment has not been maintained. According to the information provided by TEPCO since March 16th, radiation doses inside the containment vessel are extraordinarily high, in the range of 50 to 100 Sv/h (maximum values) for all the Units 1, 2, and 3. This suggests that much fuel could have already melted and moved down to the bottom of the pressure vessel.
1-4. Massive Release of Water Contaminated with Radioactivity
Cooling water in the core of the reactor was designed to circulate, but obviously it is not circulating now. Water poured into the reactor core moves in a highly contaminated condition into the containment vessel. It further escapes in large amounts through the damaged parts of the containment vessel into the surrounding site of the nuclear reactor, including the attached turbine building. At present (March 31st), the condensers in each of Units 1, 2, 3, and 4 are full of water, so workers are trying to transfer this sort of water to the surge tank. As long as the release of cooling water continues, it is clear that the surge tank too will be full sooner or later. We proposed to the government that it should call barges to take the contaminated water, but the government failed to respond to the situation in a timely fashion. This led to the emergency measure on April 4 of releasing water contaminated with comparatively low concentrations of radioactivity into the nearby ocean from the reactor site.
1-5. When Will the Accident Be Resolved?
The fuel rods inside the reactor core must constantly be cooled by water. To avoid the release of cooling water into the environment, it is necessary to re-activate the cycling system of cooling water. For the cycling system to operate, power (electric power) and water must be supplied to the pumps, and there should be no leakage in the circulatory system (the nuclear reactor itself and the piping). At present, however, either the bottom of the pressure vessel or the piping is damaged, so water cannot circulate. Given the high radiation levels, workers cannot repair the damage. Accordingly the prospect of recovering the cooling water circulation function is very slim.
The amount of radioactive decay heat will gradually diminish, but it will take years before the cooling water system becomes unnecessary. The same can be said for the decay heat released from the spent fuel rods kept in the pool. The point is how soon the circulation of cooling water can be recovered. Even if no unforeseeable event should take place, this accident will last for a long time to come. The amount of radioactive materials released into the environment (atmosphere and water) will be quite sizable. It could reach an amount equivalent to the nuclear accident in Chernobyl (1986).
2. How Far Will Radiation Contamination Spread and How Long It Will Last?
2-1. Critical State of Fukushima Prefecture
In the zone between a 20 km and 30 km radius from the crippled nuclear plant the residents were initially ordered to stay inside their residences to avoid radiation exposure. Now they have been requested to move away from the zone on a voluntary basis. Despite the alleviation of the safety warning, however, they continue to face difficulties and chaos in their daily lives. An increasing number of people have evacuated even from areas outside the 30 km radius sphere. From the outset, it was possible to predict the pattern of regional contamination, but an evacuation warning for the residents living outside the 30 km radius sphere has not been announced. The government should issue one as soon as possible.
The problem that must be tackled as the next step is the safety of those who live near the 50 km radius. Included in this sphere are mid-size cities such as Fukushima City (population 290,000), K?riyama City (340,000) and Iwaki City (350,000). According to the data made public by Fukushima Prefecture, the radiation exposure level in Fukushima City 63 km northwest of the Fukushima Daiichi Nuclear Plant ranged between 2.39 and 3.31 Sv/h from March 31st to April 2nd, and in K?riyama City 61 km west between 2.27 and 2.79 Sv/h. For five days both day and night, the radiation exposure level remained high. The actual readings of radiation exposure gradually declined from the high of 22.8 Sv/h in Fukushima City on the night of March 15th when a hydrogen explosion occurred at the building of Unit 3. In K?riyama City they recorded a drop from 3 Sv/h down to 1 Sv/h, but then a rise to 2 Sv/h. In Iwaki City located 43 km to the south, the reading showed a high level of 5.04 Sv/h on March 21st, but since then the levels have been low at 0.6 Sv/h. No doubt, differences in contamination levels among the three cities are caused not only by their distances from the nuclear plant, but also by the direction of the wind and geographic configuration.
The accumulated radiation exposure in Fukushima City from March 15th through April 2nd exceeds 3 mSv. If the present conditions persist, the annual radiation exposure in Fukushima City will be 22 mSv (=2.5 Sv/h x 24 h x 365 days). This is a quite high level of radiation exposure, a level too dangerous for pregnant women, infants, and children to continue to live under. Even adults should avoid living within this level of radiation exposure.
Neither the national government, nor local authorities, nor our group can offer any definite solution as to what must be done for the residents of this sphere. Local authorities might start investigating some possible measures, particularly for pregnant women, infants and children, including "the evacuation of children."(During the Second World War, the Japanese Government evacuated school-aged children from the urban areas targeted for aerial bombing to countryside. [translator]) For adults, it is recommended that the radiation monitoring data should be carefully studied and that, if necessary, an evacuation order be issued promptly for clearly designated regions. Yet, the area that may well be contaminated covers more than half of Fukushima Prefecture's population of two million. We are now confronted with an extremely difficult situation. It is all the more necessary for us to be aware that the disaster has created a grave situation.
2-2. ICRP Proposal to Increase the Radiation Exposure Limits
There are some attempts to deal with this spreading contamination. On March 21st, the International Commission for Radiological Protection (ICRP) proposed drastically increasing the safety limit of radiation exposure for residents as an emergency measure. The current permissible limit of radiation exposure is set at 1 mSv per year, but according to the new limit, people would be permitted to reside in the designated area up to the level of 20 mSv per year.
The ICRP recommendation concerning radiation exposure was based upon the probability of death from cancer, according to which, when each of the residents in a city of 100,000 continues to be exposed to radiation at a rate of 20 mSv per year, there will be an additional 100 cancer deaths per year. It is not easy to identify radiation exposure as the cause of their death from other causes, so what can be detected will be a general increase in mortality in population statistics. In view of this statistical ambiguity, the recent ICRP proposal to raise the radiation exposure limits for the residents of the contaminated area implies acceptance of a larger number of deaths from cancer caused by radiation exposure as a consequence, so there are serious problems with the ICRP proposal.
2-3. Contamination of Food, Soil and Water.
Radioactive contamination has begun to spread to soil, water, and food beyond the domain of air contamination. Not only within Fukushima Prefecture but contamination has also been observed in Tokyo and Ibaraki Prefectures. Figures higher than the safety limits for tap water in Tokyo and for vegetables produced in Ibaraki have been reported. Consequently, public authorities have issued recommendations to reduce infants' intake of tap water and to withdraw contaminated vegetables from the consumer market. Since then the figures have remained slightly lower, but it is publicly acknowledged that the area contaminated by radioactivity now extends from the northern part of the Kanto region to the southern part of the Tohoku region. Indeed the degree of soil and water contamination is dependent upon how the nuclear reactor accident will be dealt with. Even without large-scale releases of radioactive materials into the environment due to an explosion, the accident will persist for several months at the very least, and radioactive materials will continue to be released.
The contamination of the nearby ocean and underground water around the plant site also poses a grave problem. On April 2nd, a high concentration of Iodine 131 was detected at the drainpipe outlet. Tokyo Electric Power Company then announced that a pit connected to the trench at Unit 2 was cracked, so water contaminated with a high level of radioactivity was released into the sea. Iodine 131 and Cesium 137 were identified even as far as 30 km away from the shore of the nuclear plant. It is now evident that the contamination is spreading widely in the ocean. On April 5th, Japanese sand lance (ammodytes personatus) caught off the northern coast of Ibaraki prefecture was found to have radioactive contamination of 526 Bq/kg, which is higher than the safety regulation value. We must keep in mind, however, that we are still in the early phase of contamination. There is no doubt that marine creatures will be further contaminated through bioaccumulation from now on.
2-4. Solidarity with Farmers through the Consumption of Their Produce
Vegetables and milk were removed from the consumer market. Producer farmers were forced to ditch these specified items. Furthermore, the farm produce market is hit by consumers' general hesitation to use farm products from Fukushima and Ibaraki Prefectures.
The pace of the spread of radioactivity will very much depend upon the release amount and geographic spread of radioactivity. Public attention will be diverted from the short-term contamination by Iodine 131 (half life 8 days) to the long-term contamination of soil and water by Cesium 131 (half life 30 years) and Cesium 134 (half life 2 years). Undoubtedly the contamination problem of agricultural and marine products, in which radioactivity will be absorbed and accumulated, will persist for a long time to come.
Some of the mildly contaminated agricultural and marine products, whose degree of contamination does not exceed the temporary safety standards, have been made available in the consumer market, but this does not mean that these mildly contaminated products do not contribute to the radioactive accumulation process. Precisely for this reason, it is highly likely that consumers will be hesitant to purchase products from Fukushima and Ibaraki Prefectures. The negative economic impact on agricultural and marine products is referred to as "reputational damage". The Japanese Government and local authorities have been dealing with this through a safety publicity campaign. But, there is a fundamental misunderstanding in this. The safety standard value does not imply that a product whose degree of contamination is below the standard value is safe no matter how long one continues to eat it. It is a value determined in ways similar to the radiation exposure limits in the residential environment.
With this in mind, we must ask ourselves whether we should be satisfied with shunning products from Fukushima and Ibaraki Prefectures altogether. Do we not need to think about the situation in which residents in the Fukushima Prefecture find themselves? Precisely because they live in Fukushima Prefecture they are now unable to sell their own produce. (They cannot expect governmental compensation because they are not prohibited from selling their produce legally.) Is this not too great an adversity for the Fukushima people to bear? The residents of the Tokyo metropolitan area (comprised of the Tokyo prefecture and its neighboring prefectures, [translator]) have benefited from nuclear energy produced at the Fukushima Nuclear Plants and the Kashiwazaki-Kariwa Nuclear Plant. Even if they did not actually want nuclear energy, they have lived on this supply and have taken it for granted for a long time. When people who have helped us are now being challenged, should we not express our solidarity with them in one way or another? It is of course reasonable that agricultural produce contaminated with radioactivity beyond the safety standards be discarded and its producers compensated. As far as the mildly contaminated produce for which the degree of radioactive contamination is below the safety standard values is concerned, we should not refrain from consuming it as long as we take the utmost protection measures and pay attention to the condition of the contamination . It goes without saying that extra caution must be taken with regard to infants, who are 9 times more vulnerable to the effects of Iodine 131 than adults, as well as to older children who are 5 times more vulnerable.
3. Responsibility of Corporations, the Nuclear and Industrial Safety Agency, the Nuclear Safety Commission, and Academics.
As soon as the accident was disclosed, many who had denied the feasibility of a Nuclear Plant Disaster issued an "excuse" that the accident was "beyond prediction." Were the earthquake and the tsunami truly unpredictable?
3-1. The Great Tsunami was Predictable.
In the history of Japanese Seismology, a Richter Scale magnitude 9.0 earthquake was unprecedented. But, we witnessed the M. 9.0 Indian Ocean Earthquake off the western coast of Sumatra and the subsequent tsunami in December 2004. Therefore, it is disingenuous to claim that the East Japan Great Earthquake and Tsunami was "beyond prediction."
It is recorded that along the Pacific coast of the Tohoku region a great tsumami called "Jogan Otsunami" took place and hit the capital of the domain of Mutsu on July 869. A recent study has disclosed its scale and reminded us of the possible reoccurrence of an earthquake of that magnitude after 1100 years. The possibility of an earthquake of this scale was actually indicated by one of the members of the assessment committee during the discussion sessions (in June, 2009) for the mid-term review on earthquake resistance conducted by Tokyo Electric Power Company in response to the revision of the earthquake resistance guidelines. Nevertheless, the evaluation of tsunami impacts was postponed until the final review, and the recent tsunami hit the plant before it was publicly available. The members of the evaluation committee, the Nuclear and Industrial Safety Agency and the Nuclear Safety Commission should have demanded TEPCO to produce an evaluation of tsunami impacts and appropriate countermeasures.
3-2. Inadequate Safety Consideration for Earthquake Resistance
The expression that the tsunami was "beyond prediction" seems to imply either that the nuclear plants would have withstood the earthquake if not accompanied by the tsunami or that the earthquake resistance design was adequate if precautions are taken against the impacts of a tsunami. Can we readily accept that the equipment and instruments were damaged in this accident simply because of the tsunami? According to the earthquake records (preliminary data) made public by TEPCO, recorded values at the lowest basement of the nuclear reactor buildings of Units 2, 3, and 5 exceeded the accelerations corresponding to the standard ground motion Ss. At Units 1 and 6, the recorded values were almost at the level of the standard ground motion Ss. Obviously inadequate consideration was given when the standard ground motion Ss for the nuclear reactor buildings was set.
Since no investigation of the interior of the reactor buildings has been conducted, we can only speculate at the moment. It is quite possible that the earthquake could have caused the loss of outside electric power, damage to the emergency core cooling system, the fracture of the suppression chamber, damage causing the drainage of coolant, and so forth. If these damages were caused by ground motions below the standard level, the earthquake response analysis of the plant equipments must also have been inadequate.
In summary, should we not conclude that "the prediction" not only of the tsunami but also the earthquake was seriously inadequate? It is misleading to say that the Fukushima Nuclear Disaster was caused by unforeseeable factors beyond human recognition. It was brought about by a fundamentally misguided safety assessment. The new earthquake resistance review (2006) admitted "extra risks," but TEPCO neglected to undertake proper actions. There lies the core of the problem.
3-3. Responsibility of Corporations, the Nuclear and Industrial Safety Agency, the Nuclear Safety Commission, and Academics.
How were the safety standards set up to ensure the safety of the nuclear plants? What we learned during the reassessment process on the evaluation of the integrity and the seismic resistance of the Kashiwazaki-Kariba Nuclear Plant was that the corporation responsible for the nuclear enterprise conducts a safety assessment of a nuclear plant only so as to guarantee the resumption of its operation. It is not hard to imagine that the reassessment conducted at the Fukushima Nuclear Plants was no exception.
Such a re-assessment was submitted by the Tokyo Electric Power Company, the corporation responsible for the nuclear business at the Fukushima Nuclear Reactor; it was discussed and authorized by the Nuclear and Industrial Safety Agency; it was examined with regard to the plant's safety, supposedly from a neutral and independent stance, by the Nuclear Safety Commission; it was uncritically endorsed by academics. We have no choice but to emphasize the responsibility of the corporation, the Nuclear and Industrial Safety Agency, the Nuclear Safety Commission, and academics for the Fukushima Nuclear Plant Disaster.
On March 31st, Tanaka Shun'ichi, a former member of the Japan Atomic Energy Commission, Matsuura Shojiro, a former chair of the Nuclear Safety Commission, and Ishino Shiori, professor emeritus of Tokyo University held a press conference representing sixteen scientists and engineers. They issued an Emergency Statement concerning the Fukushima Nuclear Accident. At the beginning of the Statement, they said, "Representing those who have guided the development of the peaceful use of nuclear energy, we feel profound regret for the recent nuclear accident and wish to express our deepest apologies to the nation." In press coverage, their apologies were highlighted, but unfortunately no mention was made of the fundamental problems underlying the nuclear energy promotion movement that led to this disaster.
3-4. Ability of the Government and TEPCO to Respond in Emergency
At 3: 30 pm on March 12th, one day after the great earthquake, a large-scale hydrogen explosion took place on the top floor (the operation floor) of the nuclear reactor building of Unit 1. By chance the containment vessel managed to remain intact, but radioactive materials could have been spread into the air in large quantities. From the reports by the government about the emergency situation we can hardly find any indication that either the Nuclear and Industrial Safety Agency, TEPCO or the Nuclear Commission foresaw the possibility of a hydrogen explosion. Immediately after the explosion, some pro-government academics boasted that "the soundness of the containment vessel was proven." In fact, we were lucky to escape a larger disaster as a result of sheer chance. Two days later, in relation to a similar hydrogen explosion that took place at Unit 3, they did not bother to issue a new evacuation order to the residents of the nearby area when they issued an "explosion warning" that said "a hydrogen explosion similar to that of Unit 1 might happen." In fact, the second explosion was larger than the first. All these episodes amply illustrate the Nuclear and Industrial Safety Agency and the Nuclear Commission's (and TEPCO's) lack of sense of responsibility and ability to respond to nuclear emergencies, despite the fact that the raison d'?tre for both the Nuclear and Industrial Safety Agency and the Nuclear Safety Commission is none other than to protect the lives and health of the citizens.
3-5. Necessity of Maintaining Transparency in the Selection of the Staff Members of an Independent Accident Investigation Committee
The Japanese Government has announced that it is already reviewing the procedures by which to set up both an accident investigation committee to inquire into the causes of the Fukushima Nuclear Accident and a nuclear dispute assessment committee for damage compensation to establish guidelines to determine the kinds and extent of compensation according to the Nuclear Compensatory Damage Law for residents close to the nuclear plant.
It goes without saying that these investigation and assessment committees must be set up. Furthermore, it is imperative that these committees be organized and run truly as third-party organizations in order to investigate the truth of the accident, to establish effective prevention measures, and provide genuinely appropriate damage compensation. For these purposes, the selection criteria for their members and their management require vary careful planning and deliberation. We make the following concrete proposals:
--- The members should be selected on the basis of a public call for applications;
--- In addition to candidates' academic, professional careers and publications, their past involvement in and opinions on the matters of nuclear safety must be available to the public;
--- Transparency in the procedure as well as the criteria for selection must be guaranteed;
--- It is important that, regardless of nationality, people experienced in the actual operation of nuclear reactors and with expertise in nuclear technology must be sought for the Accident Investigation Committee both inside and outside Japan.
Statement by Scientists and Engineers Concerning Fukushima Daiichi Nuclear Power Plant (no.1) (March 23, 2011)