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  On March 11 last year a magnitude 9.0 (Mw) earthquake hit off the coast of Japan triggering a powerful tsunami and resulting in the most serious nuclear accident since Chernobyl. Over 15,000 people were confirmed dead as the tsunami inundated a total area of approximately 561 km2 (217 sq mi) in Japan. A series of fires and explosions within the Fukushima Daiichi nuclear power station triggered a full meltdown in three reactors whilst a fourth was significantly damaged by fire. The Fukushima Daiichi nuclear disaster was rated as a level 7 (major accident) on the international nuclear and radiological event scale. Now, one year after the disastrous events unfolded, nuclear and disaster experts examine the current situation and what lessons can be learnt.

  Below are comments from Japanese experts provided by the Science Media Centre of Japan and translated into English by Translationz. The collaboration between the Australian Science Media and the Science Media Centre of Japan is supported by the Commonwealth through the Australia-Japan Foundation which is part of the Department of Foreign Affairs and Trade.

 

Tatsujiro Suzuki

Vice-Chairman of the Atomic Energy Commission in the Japanese Cabinet office
 
  The present circumstances assure that Fukushima Daiichi is remarkably stable. However, the condition of the reactor core is not understood and there are still many mysteries about the nuclear reactor.
 
  At present the main concern is the radioactive material being discharged in large quantities into the air. However, I think that this is a short-term concern. I feel as a future prospect, the treatment of contaminated water being generated in large quantities would be more important. The water is being processed; it however is not decreasing. The people at Fukushima Nuclear Power Plant are suffering a lot due to this. The influx has already entered the sea. Effort is being made to build a fence, however this would take time. Groundwater is flowing under the power plant; hence one has to keep watch on underground penetration. In the case of the contaminated water, a liquid waste disposal process has to be set up as it is a high level radioactive waste.
 
  Robots started operating at the power plant a few days ago. However, in the long run, measures have to be taken against the discharge of nuclear fuel. According to an expert of the Atomic Energy Commission, it would take around 30 years for the complete containment of the Fukushima Daiichi accident. There are many matters which have not been experienced so far. Atomic energy experts as well as the best brains from the world over must come together to find the solution to this problem. The government is working towards forming such a system.
 
  When we talk about the area outside the nuclear power plant, the contamination is spreading and a feeling of insecurity has developed amongst the citizens. Hence I think it is necessary that the government and the power company should have a deep sense of responsibility and should search their conscience. I think that the contamination outside the nuclear plant would not affect the health of the citizens. I, however, am extremely sorry that the entire country has fallen into despair due to this.
 
  The government now is trying its best for decontamination. First of all, it is important to provide accurate information for monitoring. Disbelief still exists in the figures provided by the government. The government is putting in effort, but there might be problems in the approaches adopted. The style of communication is bad, the efficiency is poor, the process is not well designed; hence the residents are not feeling relaxed as yet. ICRP is also stating that the residents should be taken into confidence and then decisions should be made together. However the scene has not yet changed. Things are decided by the scientists all by themselves and then they are simply conveyed. The decision making process is not convincing. Therefore there exists a sense of distrust. And this has to be changed.
 
  In the case of decontamination, the standards for external exposure (to radiation) have been set. The annual external exposure of any area should be less than 20mSv. If this isn't the case, people are not permitted to live there. However if it is less than the set standard, the residents can return to their homes. Hence, in the short run it is important that the areas with external exposure of 1~20mSv are decontaminated and made available for the residents. At present, data collection for decontamination has been stopped. It would, however, being full scale from April. As far as decontamination is concerned, there are challenging topics such as the hot spots (the area where the radiation dose is high locally) being jumbled up and the contamination levels desired by the agricultural people and those desired by the common man are different etc. Normally, monitoring is required to be done along with the residents before the decontamination. However it could not be done in this case. In addition, the present grid of monitoring is oversized. If possible it should be done within 100 meter ×100 meter. Even this is not feasible due to shortage of manpower. We would like to collaborate with various people and find out the best approach.
 
  In the long run, it is necessary to differentiate between areas where residents can return and those where they cannot. This should be done at the earliest possible time. However, this needs a political decision. The residents build up expectations when the scientists state that “decontamination is possible”. However the areas where residents cannot return need to be clearly decided with the judgment of experts.
 
  In addition, the citizens have a sense of distrust concerning the safety of other nuclear power plants. This was a tsunami and earthquake beyond the control of the safety standards. Hence now new standards should be created which would factor in such disasters. And the nuclear power plants must comply with these new standards. It is very difficult to create new safety standards in a short time span. Therefore, a stress test needs to be conducted. It seems that easy-to-follow restart criteria are not yet given. I think it is not necessary from an energy demand and supply point of view. However, if a new regulatory agency is formed then it would specify the standards of restart for the nuclear plants which are not operational at present. The new regulatory agency would do its best to convince the residents and make the nuclear plant operational.
 
Future energy policy of Japan
  As far as energy policy is concerned, in the short run, the demand and supply measures for this summer must be formulated. Relevant data is now being collected. Investigations are also being made on the assumption that electricity generated using nuclear power would be zero. In the long run, the only decision that has been made is that dependency on nuclear power plants would be reduced. Discussion over the future energy mix is not clear. The government has promised that it would provide the alternatives by this spring and things would get decided with a national debate in summer. As national debate is a new concept, it would require cooperation from the government as well as the entire nation including experts from various fields. We need to urgently find a process which would convince everyone that “The decision was taken after a debate”.A significant philosophy needs to be formed to decide the energy mix with certain standards, as a society. I think apart from the debates by the government commission, it would be better if the debates are done everywhere and communicated to the government at the end.
 
※ SMCJ Comment: Tatsujiro Suzuki was associated with sociological studies of science and technology through technology assessment research. He is also active in interaction with the society. Hence, in Japanese organizations where there is a strong tendency of confining issues bureaucratically, he is considered as a significant spokesman of Cabinet office Atomic Energy Commission.
 
 

Assistant Professor Hiroaki Koide

Kyoto University Research Reactor Institute
 
Things which have been learnt one year after the Fukushima disaster
  We’ve realized that we don't know anything. If the accident was at a thermal power plant, it would have been possible to inspect the actual accident site and find out the details. However, in the case of a nuclear power plant disaster it is not possible as there are radioactive materials. The people who were promoting nuclear power generation so far say that the disaster was “unanticipated". As the accident was unanticipated, the measuring devices required to investigate the cause of the disaster are also not installed. Furthermore, the so-called measuring devices which were installed have broken down. It is of utmost importance to know the whereabouts of the nuclear fuel, and the melted reactor core. These facts however are not known.
 
Future prospects
  If we talk about the scene at the nuclear plant, then the problem is that we don't know the extent the melted reactor core would spread to. It would be important to know the kind of measures that would have to be taken to prevent the spread of the contamination. If the melted reactor core drips underground and comes in contact with groundwater, radioactive material would spread in the environment. Therefore, it is important to set up barriers beforehand and prevent such contact.
 
  Another problem is the spent nuclear fuel in the pool. Daiichi reactor 4 has been badly damaged. Efforts should be made to prevent further damage to this pool. This, however, is difficult due to frequent aftershocks and the high radiological dose levels. In the event of a big aftershock and the pool breaking down, the spent nuclear fuel would spread in the environment in the absence of a barrier. The workers have already started clearing up the debris. Moreover TEPCO might be looking at this problem as a top priority.
 
※ SMCJ Comment: Hiroaki Koide is considered by the Japanese media to be a pioneer among the experts who have adopted a stance supporting denuclearization. He has mentioned his stance in a well-known Japanese national daily as well as in weekly magazines. He is in the limelight in the alternative media.
 
 

Assistant Professor Tetsuo Sawada

Research Laboratory for Nuclear Reactors Energy Engineering at the Tokyo Institute of Technology
 
  Various events occurred within a week of the disaster. If the systems before the disaster are compared with those afterwards, does it develop as expected? If the condition of the reactor core is taken into account, then the fuel of the reactor cores is damaged from Daiichi reactor 1 to Daiichi reactor 3. And a significant proportion of the core fuel has melted. It is not very clear about the exact quantity of the core fuel that is damaged and whether it has spread in the furnace. There is a possibility that some fuel might have leaked out of the containment vessel and some quantity has melted. I think there is no marked change according to the circumstances reported by the Tokyo Electric Power Company (TEPCO) a few days after the Fukushima disaster. For example, if Daiichi reactor 1 is taken into consideration, then it is not clear whether the percentage of the core fuel that has melted is 70 or 100.
 
  The problem of contamination and decontamination of any region due to radioactive material is a serious issue. It has been confirmed that in late March radioactive material was dispersed in areas including Itate, Fukushima Prefecture. The quantity of the discharged radioactive material and the dispersed radioactive material distribution has not changed a lot since then. Major emission into the environment stopped immediately after the disaster. However, the problem is coping with the substances that have already been discharged. Air dose rate observed in Minamisoma and Itate has not yet reduced. The matter has become serious as the circumstances are very difficult to comprehend and deal with. And it can be said that now the seriousness of the matter has increased from last March-April.
 
  There is one more point which needs to be considered seriously. Areas within a 20-kilometere radius of the plant have been left uninhabited. This area was declared as a 'no-go’ zone. However, this area has been neglected over the past year. The rubble caused by the tsunami and the wreckages of houses due to the earthquake etc. are all lying untouched. If the situation continues like this then there would be much deterioration and decay. Furthermore, if there is new vegetation growth then it would advance the immobilization of the radioactive material. It has been also heard from the residents who have returned that the circumstances are getting worse due to the stand adopted.How does one process and control the radioactive material that has been discharged into the environment? How can the people from the affected area cope with the radioactive material? These issues are very important. However, their solution is difficult. There was some information available from the knowledge gained following the Chernobyl accident, regarding the discharge of cesium in large quantities. However, I now comprehend the present circumstances and their gravity, after my frequent visits to Minamisoma and Itate, listening to the tales of residents after the actual discharge. It can be said that even my thoughts have changed.
 
  An atomic energy regulatory agency is to be established in April. It seems that though the organizational structure of the agency would change, the content would be almost the same. I, however, am not clear as to how it should be. Neither am I in a position to comment on it. The future concern is the measures for the Daini power plant. There are frequent big earthquakes in this area following the earthquake in Sumatra in 2004. The possibility of a future earthquake of the same magnitude and that could possibly lead to a tsunami also exist. If such a situation occurs then the Fukushima power plant will become even more compromised. The circulatory system of the cooling pool of the reactors need to be maintained. It is necessary to have preventive measures in order to maintain the present cold shutdown, just in case something else goes wrong.
 
  Lastly, there is another concern regarding the water shielding wall. At first, there was a situation when the water accumulated in the reactor building and the trench would not lessen even after being pumped out. The chances of groundwater leakage have been stated. Therefore it was decided to build a water shielding wall as a temporary measure. Since it would cost approximately 100 billion yen to build it, TEPCO took the stance that it would only build it if it got support from the Government. As a result the plan was cancelled. Even at this point in time, the relation between the groundwater flowing under the power plant and the water flowing outside it is not known. There might not be a leakage of contaminated water on a large scale. The question of quantity remains. I think there is a possibility of leakage being present at the moment.
 
※ SMCJ Comment: Tetsuo Sawada faced the media as an expert after the earthquake disaster and tried to explain the situation. As a result, he became popular as 'a scholar beholden to the government' on the Internet. However, at present, as one of the founders of the Minna-no (Everybody's) Energy and Environment Conference (MEEC, http://www.meec.jp/ (only in Japanese), he is participating in a debate for social decision making regarding future energy policies including alternative energy.
 
 

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