フクシマの女たち・福島原発告訴団団長・武藤類子さんによる 2018年フクシマ原発事故7周年に向けたメッセージ

Ruiko Muto                Member of Fukushima Women Against Nuclear Power Chair of the Complainants for the Criminal Prosecution of the Fukushima Nuclear Disaster

To all whosethoughts are with Fukushima

It’s been seven years since the Fukushima Nuclear Disaster on 11th of March 2011. I would like to wholeheartedly say thank you to all the Fukushima supporters.

These days in Fukushima, we often hear such words as “repatriation,” “reconstruction,” and “health creation.” With the Tokyo Olympic Games 2020 approaching, a huge investment has been made to redevelop disaster-struck areas. Research centres for decommissioning technology and for robotics, wind farms, mega solar parks, as well as biomass generators are being build in severely devastated coastal areas as a part of “Innovation Coast Project.” Futaba Town, one of the most heavily contaminated areas located in the immediate vicinity of Fukushima Daiichi Nuclear Power Plant, plans to host an archive centre to record damage inflicted by the disaster, and an industrial centre in an attempt to attract study trips from high schools. Fukushima Prefecture is soon reopening the whole length of a major motorway on the eastern coast, trying to repatriate all the Fukushima evacuees.

On the other hand, however, there are a string of human rights violations on a huge scale. The current repatriation scheme does not mean that you can return to a thoroughly decontaminated, safe area. Instead, it means that you have to live with the contamination as long as the dose is claimed to be under 20 millisieverts a year. This threshold is 20 times higher than the allowable dose for citizens everywhere in the world before the disaster. There are no publicly funded recuperative support plans for the repatriated children. Financial compensations and housing subsidies are cut even if you decide not to return. There are people who have no choice but to return to the still-contaminated area for financial reasons. Some are resigned to become homeless and others have felt so devastated that they have taken their own lives. Some evacuee families have been sued  for eviction from their shelters. In the UN Human Rights Council, four member states have recommended corrective actions over the human rights situation in Japan.

The situation within the Fukushima Daiichi Nuclear Power Plant also remains highly critical. There are now over 800 tanks, each of which contains 1000 tons of tritium-contaminated water. The current and previous chairmen of the Nuclear Regulation Authority have insisted that pouring the tritium-contaminated water into the ocean is the only solution, and they are attempting to gain consent from local authorities. For me, this is the first ocean I saw in my life as a four-year old girl. I can still picture the scenery in my mind. It was one of the three greatest fishing places in the world, with rich marine life. The ocean connects many places all over the world. Now that Fukushima Nuclear Disaster has already caused massive radioactive contamination of the ocean, I don’t wish to exacerbate it by letting the contaminated water in the tanks flow in, further contaminating the ocean. It is unbearable for me that the government is indeed trying to promote such an action despite the fact that they should  be trying to stop it. The local fishing industry is desperately trying to prevent the release of tritium-contaminated water into the ocean. I have to ask you all over the world to raise your voice with them.

The number of people in Fukushima Prefecture having thyroid cancer, or having large cysts that indicate possible thyroid cancer, has risen to 193. The Oversight Committee for Fukushima Health Management Survey continues to insist that it is “unlikely” that the Fukushima Nuclear Disaster caused the surge in the number. What is worse, it turned out last year that there were unreported thyroid cancer cases. People who were deemed “in need of follow-up observation” at the first screening and then individually received thyroid cancer diagnosis before going through the next screening, did not appear in the statistics. Faced with criticism from some committee members and citizens, Fukushima Medical University has decided to look into the matter. The investigation, however, is supposed to take as long as two years. Despite the fact that this survey is the only one that examines the health conditions of Fukushima victims, not even a correct result has been provided. There are also people trying to diminish the scope of the health survey, using phrases like “overdiagnosis,” “a health survey in school violates human rights,” or “people have rights not to know.” I think Fukushima Prefecture, which refused to even distribute iodine at the beginning of the nuclear accident, has a responsibility to continue carrying out the thyroid cancer survey.

Two years ago I was surprised to learn that high school students visited Fukushima Daiichi Nuclear Power Plant to observe decommissioning works. Now Fukushima University has also started to provide students with opportunities to visit the plant as a part of their curriculum. With the aim of developing robots that can be used for decommissioning work, technology students from all over Japan are encouraged to join robotics competitions in Fukushima. Commutan Fukushima, a facility in my town built for the purpose of radiation education, helps children learn through visual aids and games. There have been 100 thousand visitors during the year since its opening. There I had an opportunity to read messages left by visitors. Many children wrote “I was scared of radioactivity, but I am glad to be reassured that it exists in the natural environment and foods, ”  or “if everyone learns here, Fukushima will no longer be discriminated.” As such, the aim of the facility seems far from educating the children how to acknowledge and protect themselves from the danger of radioactive substances that still surround us.

Meanwhile, various lawsuits are going on in order for the victims to be properly compensated, to correct administrative procedures, or to demand criminal convictions for those responsible for the disaster. In a civil case, the court decided that Tokyo Electric Power Company (TEPCO) and the Japanese government neglected necessary precautionary measures against Tsunami. More judgments are expected this year. Hearings of the case brought by 14 thousand complainants for the criminal prosecution of TEPCO executives finally started last June. Although the three former top executives of TEPCO pleaded not guilty, prosecutors started the legal procedure with ample documents and facts to prove TEPCO’s negligence over the risk of Tsunami. I would like everyone to keep an eye on the proceedings. We are collecting signatures to petition for a truly fair trial. We have an English version of the petition form ready on our website: http://kokuso-fukusimagenpatu.blogspot.co.uk/p/please-sign-petition.html

This winter was very cold in Fukushima, too. Under the icy ground, however, plant seeds are waiting to sprout in the spring. Let’s not forget to dream about a new era, while living this moment with sincerity. Let’s keep our solidarity, just like oceans unite the world.

March 2018

(Translated by JAN UK)


March 11th.

My thoughts and prayers go to those who had lost their lives, who had lost loved ones and who had lost their homes by the earthquake, tsunami and nuclear power plant disaster in Japan.

This year will mark the anniversary of the Fukushima nuclear disaster and the 30th anniversary of the Chernobyl disaster. Do you remember the horrific pictures of the explosion at Fukushima Dai-ichi nuclear power plant? Trillions of becquerels of radiation have been diffused and contaminated water has been running into the Pacific Ocean. The government doesn’t know yet what to do with increasing radioactive waste and countless bags of decontamination waste are stored in eastern Japan.

Approximately 80,000 people still live in temporary housing as their homes remain uninhabitable due to radioactive contamination. Chernobyl proved that long-term exposure to even very low levels of radiation can cause health damage. In Germany eight reactors are still in operation and the recent accidents of Belgium’s aging nuclear plants worry neighboring countries. After Fukushima, Europe is now again faced with danger.

There is no official accusation of TEPCO, who is responsible for the accident. Without learning its lesson from the Fukushima disaster, the Japanese government is eager to restart nuclear power plants and has just restarted four reactors. Many of the Fukushima evacuees will have to choose to return home as the government will lift the evacuation order in 2017. This also means the government will no longer have to pay compensation to evacuees. Instead of securing continuous fair support for the evacuees, Japan is going to pour 1.8 trillion Yen (15 billion euros) into the Tokyo 2020 Olympic games. Not only that, Japan is selling nuclear technology to India, Turkey, and Vietnam and the major Japanese manufacturers of nuclear power plants are trying to make profits outside of Japan, together with European companies.


A voice from Fukushima (Interviewed Feb. 2016)

I fled from my home and am currently living 80km away from the nuclear power plant. We are facing a huge dilemma –  we will soon be forced to move out from our temporary housing. Due to political decisions we are being forced to return home, but I’m very concerned about radioactive exposure and I’m worried about whether we can earn enough money to live on. 

It makes me angry when I hear politicians discussing sending us back home. I think they are taking radiation issues too lightly! They decontaminated the residential areas and the government announced the lifting of the evacuation order because they said that the level of radiation has gone down. But do you think anyone wants to live in a place surrounded by bags of radioactive decontamination waste?

When Tokyo was selected for the 2020 Olympic games and Japan was full of excitement about that news, I felt that something was terribly wrong. I felt that the suffering and the pain of those who were affected was totally ignored and I felt hurt by the TV coverage that acted as though the nuclear accident never happened. I try not to think about the Olympics and I don’t want to watch the news because I believe it is manipulated.


We forget easily what we can’t see. But the invisible radiation continues threatening our planet and lives. Leaving a negative legacy of unsolved nuclear waste for future generations is no longer ethically permitted. Nuclear energy and human beings cannot co-exist as Chernobyl and Fukushima testified. The energy transition in Germany is not enough to solve global issues. Until all nuclear reactors are decommissioned and uranium mining is stopped worldwide, we will be faced with danger. If you feel that nuclear energy isn’t necessary, say it out loud! Every one of us is a part of political decision-making. You might think your voice won’t be heard, but all our voices together can make a difference.

Please join us at Kazaguruma Demo on 19th March in Berlin –  “Fukushima and Chernobyl urge Nuclear Phase-Out Worldwide!”


Learn more : 100 Good Reasons against nuclear power     http://100-gute-gruende.de/index.xhtml


ソーラーハウス (Effizienzhaus) 見学

At February 1st, 2016, some of us visit to a solar house in Berlin, Fasanenstrasse. The minister of Environment, nature protection, construction, and reactor safety (Bundesministerium für Umwelt, Naturschutz, Bau und Reaktorsicherheit) built the house as an experiment of energy efficient house. The name of project is “Effizienzhaus Plus mit Elektromobilität.” This means efficient house plus with electric mobility.

They built 35 experimental houses in Germany. Each house has own outlook designed by different architect. The house in Berlin is shown in the picture. It has a modern cubic shape. But of course there are houses that outlook is a classic German house, too.

Berlin にある Effizienzhaus Plus
Effizienzhaus Plus in Berlin
Effizienzhaus Plus
An explanation session in a Effizienzhaus Plus

The house is called an efficient house however also “plus” is in a name. The goal of this house is to show “generating more energy than consuming it through a year.” This includes the energy of one electric car. In the experiment process, a few public offered families live in each house for a year. Two families lived in this house so far.

The house generates energy by solar panels and store it in the batteries. The architect puts the panels on the west and east side walls and the top of the house. It would be more efficient if the panel is at the south wall, however, a typical family consumes energy in the morning, the afternoon, and at night, but not in the noon time. If they use energy directly, it is more efficient. The south side has a large glass window to get the sun light. The architect made outside looking more important than the panels efficiency, so he has chosen a specific color panels but lower energy efficiency (10 to 15%).

Heating is the largest energy consuming component of typical house in Germany. Therefore most of the effort of saving energy is related with heating. In this house, the triple layer glass is used for the window. The ventilation system uses a heat exchange mechanism. The heating uses a heat-pump system. Efficient LED lights are used for the illumination. The wall is made of low thermal conductivity materials, yet the material is recycle friendly. All the house system is adapted to use electric energy, then the house doesn’t have other external dependency for energy.

Triple glass window panes with low heat transfer
Triple glass window panes with low heat transfer

The result of the first year did not generate all the energy they consumed. The house could only generate the energy consumed in the house, but not for the car. But this is an experiment. The researcher monitored the energy consumption details in the house and found the two unexpected behavior. One is the low efficiency of heat transfer system. It didn’t work as in the specification from the provided company. Thus, they exchange the device. The second problem was the energy consumption of the living room. This room was connected to the staircase and the heated air just ran away from this connection. So the architect put a glass door. The result of the second year (with the second family) was successful. The house generated the energy more than the family consumed including a car electricity. The architect thought that the motion sensor was good for saving energy for lights, but the first family had a cat. and they found out this was not so efficient.

It’s interesting for me that this house just lack of “one door” despite all the high technology for saving energy. The experience is useful. Another interesting issue in the report was about the mindset of the family. The family realized they don’t need to save energy, since the house generate it. So their mind set becomes a bit more extravagance about energy. I understand this, but is it a good for society at the end? I am not sure. This could be a question for the next experience. The architect prefers the fixed window, which you cannot open them, for the energy saving point of view. But, the family reported it is important to be able to open the window manually. It is also important for a house not only for the energy, but the house is the big place where the life is going on. So the house keeps the window that you can open them manually. All these results are published as following (online).

The following is my personal memo.

My first glance of this house was, “I don’t want to live in this house. It looks like a Borg cube!” But this is based on a specific architect and he has also limitation in design. The original plan was for three years experiment for this house and the architect can only use some limited technology. There are 35 different designs of the Effizienzhaus Plus. I found some houses attractive. But I like the inside design of this house.

My impression is that the technology is matured. This house was built at 2012. At that time, the German technology of this area was

Energy generation instead of energy saving

I first said about the design. This means that it is already not the technical issue even in my mind. I felt the design was important. I felt that the technology is matured. I recall when the five color iMac showed up in 1999. For me, the most important factor of a computer is performance, memory, and functionality. I thought “iMac? Power PC 750, 266MHz, sounds nice, but isn’t the main memory too small?” However, some of my friends told about iMac, “Which color did you buy?” I was shocked. Why color? Later I looked back that time, the computer becomes commodity. The design is very important if you put it in a house instead of an office. I understand when something became common in your life, the design matters.

The same as this house, the architect chose a specific solar panes color, and he has chosen a low efficiency panel (10-15% efficiency). He had chosen the design over the efficiency, yet to aim the primary goal. For the next generation solar panels, I think they need more colors. I already heard about such research for solar panels. The technology will create the solar panels of any colors, then we will not notice that is a solar panel one day. The design will be more important than the energy efficiency. If a house with green solar panels, you could not distinguish the house and the garden from the distance.

Other natural energy generators would go to such direction. For instance, a wind turbine would look not a wind turbine. One direction would be windmills in Netherlands, that made the scenery itself. Or a wind turbine looks like a tree. There is an vertical axis wind turbines. Maybe we could make a turbine that resembles a tree which fits in a forest. The wind turbine area becomes a park mixed the silent turbines and real trees. This is one direction of this technology. One day, we have a power plats that is a natural park. I imagine that kind of the future and I see it is good.


What can we (citizens) do to promote green energy? I sometimes think about this. There are of course many ways. Today I will introduce one of the methods using sharing economy.

The sharing economy is a type of economy that people share the goods and services. People share: code for open source, auction places with eBay, cars with Uber, rooms with Airbnb and CouchSurfing, and so on. Sometimes it is over the range of sharing and cause troubles, but, this sharing economy is popular these days.

Can we use the idea of sharing economy for green energy? I live in an apartment. I don’t have a roof for solar panels. I don’t have a garden to put a small wind turbine. However, now we have the Internet. Can someone connect between who has a roof and who wants to invest solar panels?

Yeloha [1] is an U.S. start-up company for solar sharing network, founded April 2015. For example, anyone can borrow one solar panel per year for US $64. The generated electricity will be sold to the market and some percentage will be return to the investors. Was it a good investment? Well, it is not sure as the usual investment. However, I would like to invest the future of the green energy as a citizen and definitely this helps green energy industry. Yeloha has developed a special software, that can estimate how much electricity can be generated in a year depends on the location and the building[2].

I like this idea and business. I hope the similar sharing with wind turbine, bio-gas, and other green energies. I am looking forward to
seeing this kind of activity or company in Japan and Germany, too.

Today (2016-1-23(Sat)), we see the oil price is low. Some people think that “this is good, we can use oil.” But now is the time to invest to green energy since we can use lower price energy today to prepare for our future. The green energy is local and distributed, so its price can be stable and not global like the oil price. I believe oil price will raise one day, I don’t know when, but, I believe it definitely will. To prepare that day, I would like to invest to green energy now.


  1.  Yeloha, http://www.yeloha.com/
  2. Lauren J. Young, Startup Profile: Yeloha Brings Solar Into the
    Sharing Economy,
    IEEE Spectrum, Nov. 2015

講演: 菅直人氏「危機管理-2011年3月の東日本大震災および福島原子炉発電所事故から得た教訓」

Date: 2015-10-13 (Tue)
Venue: Heinrich Böll Foundation, Berlin

We had a lecture entitled “Crisis Management – Lessons Learned from the Threefold Catastrophe in March 2011” by Naoto Kan, former prime minister of Japan.

The hosts and German politicians started by introducing this lecture then explaining the current German situation. On German energy policy they mentioned the following:

  • Referring to Merkel’s Memorandum and her plan to replace all the German nuclear power plants with renewable energy, they said: “Concerning the fact that even one of the world’s leading technology countries like Japan has faced such a catastrophic accident, it makes sense for Germany to abandon its nuclear power plants.”
  • Compared to Germany, Japan has more natural energy. Japan can use wind energy, solar energy, and energy from biomass, but also geothermal and tidal energy. Moreover Japan has world class technology. The only missing piece would be the political decision.
Sylvia Kotting-Uhl, Grünen, atompolitische Sprecherin
Sylvia Kotting-Uhl, Grünen, atompolitische Sprecherin

Then, the organizer introduced Naoto Kan. The following is a summary of Kan’s lecture.

Just after the accident [March 11th, 2011], we found out there was no crisis management in Fukushima, because everything was built on the assumption that the atomic reactor was safe. Around March 22nd (2011), I asked a specialist to evaluate the worst-case scenario. He said that all the people who lived inside a circle of 250km radius from the reactors needed to be evacuated for a few decades. Tokyo lies within the circle. 50 million people would lose their home. I recognized that in fact the problem was, if Japan could continue existing. How could we manage 50 million refugees at once if the worst-case scenario happened?

At the early stage of the accident, both the government and TEPCO did not know what happened and could neither manage to circulate information about the accident. On the other hand, the plant manager called Yoshida improvised a new way to cool down the reactors because all the common methods had broken down. Japan was saved by mainly the people on the spot, including fire fighters, police, self defense forces and TEPCO workers. According to TEPCO, the melt down of nuclear fuel emits 70Sv/h radiation. The radiation can kill a nearby person within five minutes. The containment vessel was damaged due to the high pressure, but it only had holes. Therefore, fortunately, this fuel was not dispersed into the air, but melt down into the earth. We found out that there was no simulation for such a high pressure accident, since the assumption had always been, that an accident was impossible. If the containment vessel had blown up instead of just punching holes, we would have had no idea what happened. The fuel pool of reactor IV contained nuclear fuel, but the pool had no containment vessel. We worried that the water could dry, but we could not go near due to the high radiation. However, coincidentally, there was extra water due to the delay of the maintenance work that was being done there and so the meltdown was unexpectedly avoided. “I know this is not the words from a politician, but I can only think that God protected us.” Today we still need to cool down the fuel by putting 300 tons of water every day onto it. But the containment vessel has holes, so the water is leaking. We pumped up the water and put it in tanks. But we cannot pump up all the water. It is still not under control today.

Naoto Kan, Former Prime Minister of Japan (Photo:Tsukasa Yajima)
Naoto Kan, Former Prime Minister of Japan (Photo:Tsukasa Yajima)

We are working on Fukushima’s decommissioning. The current plan says it will take 40 years, but I personally think we need more time to finish it.

I thought about the question why this accident happened. There was a chain of the causes. They also lie equally in hardware and software, by software human factors are meant. The average height of the shore line of Fukushima is around 35m. TEPCO lowered 20m of this height and reported how they save the pumping water costs for cooling down the reactors. They put the emergency electricity generators at a low place. This severely failed design caused the accident. These are hardware problems. On the other hand, there were also software problems. In Japan many accidents of this kind are caused by earthquakes, which are often followed by tsunamis. However, this possible situation was not considered. The bureaucrats who are responsible for the security of accident are not specialists for atomic reactors. For example, when I met the responsible person of the reactor accident, I asked the responsible person, “are you a specialist for atomic reactor?” The responsible person answered, “I graduated from the economy department of Tokyo University. I don’t know technical details about the reactor.” The organization for the reactor accident and the organization of the propelling nuclear reactors were the same organization. This chain of problems led to the accident.

Before 3.11 I have always recommended to sell Japanese reactors to other countries. But after 3.11 I completely changed this opinion.

After the accident, we first separated the department of the nuclear safety and the department propelling the nuclear reactors. We also changed the regulation so that it becomes more safety oriented. This basically shut down all the reactors in Japan.

We introduced a law to encourage green energy. We studied the German FIT system.

In the future, I want to abandon the fossil fuel and want to shift to all the sustainable energy in Japan. A research report says that the current human energy consumption is only 1/10000 of energy from the sun to the earth. If each country can support the energy by its own, one of the large international conflict source will be solved. It seems the national security will be better if we could shift to the natural energy. I admire Germany as a forerunner. I heard there are many different opinions in Germany, though I was quite impressed that Merkel changed the German energy policy to be based on the sustainable energy just after a few months after the Fukushima accident. I am disappointed with the current Japanese energy policy since it is not going only towards sustainable energy. However, it was revealed that the nuclear energy is not cheap. Thus, I expect the nuclear energy will be abandoned in this century due to economical reasons. But, there is no guarantee that there will be no other accident before it is abandoned. Let’s not wait until it is too late.

At the end of the lecture, Kan concluded “Fortunately, we could avoid the destruction of the country. I felt there was a protection of God. But, I don’t know whether there will be another protection when the next accident happens. My aim is to abandon nuclear reactors all over the world before the next accident.”

After the lecture, we had a lively question and answer session.

Q: Why is Japan still not able to abandon the nuclear power, even after the accident?

A: According to the opinion polls, a majority of Japanese wants to abandon nuclear power. However, the Japanese business community and the people who depend on nuclear power businesses are still strong. At the end, we need to promote the denuclearization by the election, but the focus of the last election was economy policy, and the LDP, which promotes nuclear power, won the election. Therefore we have not achieved the denuclearization.

さまざまな質問に答える菅氏 さまざまな質問に答える菅氏
Lively discussion with Kan

Q: Why do power companies, such as TEPCO, continue to promote the nuclear power even after they faced an accident like Fukushima?

A: The government wanted to promote the nuclear power, the power companies however didn’t. The government gave the power companies the authority to add up to 3% on top of the electricity costs depending on how much they invest. It is a rate-of-return regulation for power companies. In other words, if a power company has higher costs to produce power, their profits become higher. The power company can get more profit not requiring the endeavor of the company. Therefore, the power companies would like to promote the nuclear power since it can increase the profit without any effort.

The power company can abuse the rate-of-return regulation legally. For example, a power company can have an order with deliberately high cost to a general contractor. They can raise the electricity price due to the regulation, so the user must pay this cost. There could be a secret agreement that the general constructor pays back a part of the higher cost. A book recently revealed this mechanism and the pay-back is estimated at around 200 billion yen per year. The power companies use this money to promote nuclear power. Even though the accident cost 10 trillion yen, until now it was mostly covered by the tax. Therefore this situation is quite attractive for the power companies in Japan which are also favored to the many politicians.

Q: How did Japan change after 3.11?

A: I think there were many changes. One thing I would like to mention is the change in court’s attitude. The court did not use not make decisions about the safety, they used to let the experts decide since nuclear power plants are highly technical. Even though this is only true for some members, but they changed their attitude. In the future, I expect that the nuclear energy business cannot sustain due to its high costs and also the emerging of renewable energies. I believe nuclear power plants will be abandoned in this century. However, this is an economical movement and not a political movement. That is unfortunate.

Q: Will the change not happen politically?

A: I think the change might happen from grassroots movements. But they are not seen in the outcome of the national election in Japan. I heard that the German system has more weight for the proportional representation than the Japanese system. Japan uses single-member district method for election. This system has a wasted vote problem. For example, if 10% of people are against the nuclear reactor, these people’s votes are wasted in single-member district method and these 10% people are considered as 0. We need to have enough anti-nuclear people in the Japanese diet, however, Japan has not yet reached so far.

Q: How has information been verified when the accident happened?

A: At the time, critical information had been hidden, many of them are still not publically available. The communication line between TEPCO Tokyo and Fukushima site had been connected for 24 hours. However, only the information chosen by TEPCO was made public. For example, at March 15th, I visited TEPCO and asked the TEPCO officials not to retreat from Fukushima site. The video has been published without voice. TEPCO said the voice was erased by mistake, but I personally don’t believe it. Now a prosecution of the officials is carried out, so I expect more information will come to light.

Q: What kind of person is Yoshida, the general manager, who prevented the accident to become a lot worse?

A: Unfortunately Yoshida, the general manager died of cancer two years after the accident. Whether the cancer is the cause of exposure is unclear. I was able to meet him once just after the accident. I recognized immediately that he was a reliable person.

Q: How have the decisions to evacuate the site or to allow people to return been made?

A: At the time of the accident, the government’s monitoring ability was low and there was a danger that the containment vessel was going to be destroyed. So we decided to evacuate the area within a certain radius having the reactors as its center. Then, we figured out that the distributed radioactive substance depends on the wind. But this took time. Evacuation criteria differed by experts. The current criterion is 1 mSv/y. The number of children being patients is increasing, but some experts say that this is due to our checking method which is strict and makes numbers only looks like they were increasing. Municipalities tend to lower the criterion to make it easier for the people to return, since they want them to return to the area. Basically, we decide according to the experts’ opinions, but I have question this is appropriate.

Q: Why can your party (Democratic Party of Japan) not win the elections?

A: The effect of single-member district election method is strong. Within this system, we always need to get the first position in the district. Therefore, even if the 10% of the people favor our party, it is possible that we do not get a seat in the diet.

After the lecture: Kan with the host and green party politicians

最終処分の話をしようや (10): 付録 4: 最終処分の保存期間10万年の根拠は?

Is the mined Uranium safe?

We have seen the graph of “Radioactivity attenuation of vitrified waste over time.” How long time we need to keep the waste is based on the radioactive level of mined Uranium ore. I wonder if it is save. I could not find information about this. I know that not everything in nature is safe. A venomous snake, poisonous mushroom, volcano gas, … they are all natural, but not always safe. Uranium ore is in nature, but is it safe?

A Wikipedia article entitled “Depleted uranium,” Japanese MEXT (Ministry of Education, Culture, Sports, Science and Technology) stated that the toxicity of depleted Uranium is the same of the Uranium in the sea or rocks [1] (in November, 2002). This doesn’t tell much. I would like to know about the safty of Uranium ore in the first place, then why all of sudden am I talking about depleted Uranium? You might think that I switched subject. Unfortunately, this is the information that I found on the Internet, which is only indirect. I could only find two connected things that Uranium ore has danger similar to depleted Uranium and that depleted Uranium is dangerous. Assuming they are both correct, we could conclude that Uranium ore is also dangerous. Yet I doubt there are many different types of depleted Uranium (density and so on) and many different qualities Uranium ore. I don’t believe all the Uranium ore have exactly the same density of Uranium rocks. I didn’t understand this information completely. Some say depleted Uranium is dangerous and some say it is not. The former say, “it is not dangerous, but it’s a harmful substance, so it must be controlled under the law (US government), and children should not take it (WHO).” Then, Uranium ore from nature is as safe as depleted Uranium (Japanese MEXT), or less safe. You could check this out yourself in Wiki [1]. Personally I cannot judge any risk based on such low quality information. Then my decision can only be to avoid them. Without information, we cannot decide on anything. We need more information.

Also it is not clear that “the corresponding radioactivity of 1t fuel is 1000GBq.” The value is 1GBq/kg (=1,000,000,000 Bq/kg) which is quite large. Common food has a safety threshold at 100 Bq/kg. 1,000,000,000 Bq/kg which does not sound safe at all to me.

Only one thing is certain, nuclear waste needs 100,000 years to get to this 1,000,000,000 Bq/kg state.

Most of the articles about final disposal mentioned this number, 100,000 years, and they usually ask: can we keep it for that long? I think that is a wrong and meaningless question, because even if we can manage nuclear waste for 100,000 years, it is apparently not safe. As far as I can understand, Uranium ore is not safe and 100,000 years is too short of a time for final disposal.


  1. Wikipedia ja, Depleted uranium (劣化ウラン): Health considerations (in Japanese: 医学的危険性の主張と反論), https://ja.wikipedia.org/wiki/%E5%8A%A3%E5%8C%96%E3%82%A6%E3%83%A9%E3%83%B3, (Online; accessed 2014-12-21)


Thanks to Daniel S., Enzo C., Carsten W., and Nikolaus B. for the proof reading and suggestions for the English version.

最終処分の話をしようや (9): 付録 3: 測定方法で放射線の強さは変わること,放射線には種類があること

A note on the measurement of radiation dosage

I realized that the dosage depends on how you measure it. This also depends on the measurement location. The measurement depends on the height of the measurement device. (Thus, it is mandated to be placed at the height of 1.5m above ground level.) If you clean up the measurement point, the dosage at that point becomes lower. We should care about the hotspot (a relatively small spot that has high radiation), however, we cannot say that the whole region has high radiation just because of one hotspot. In an extreme example, if we can avoid all the hotspots and the rest of the place has no radiation, we can just avoid all the hotspots and live safely. The existence of hotspots is just telling us that there could be some dangerous spots. When we observe some hotspots we usually need more measurement points. It could be that the measurement points are too sparse and we might miss some of the high radiation points. We should care about how the radiation is measured and we need to think about the risk ourselves.

For example, if the measurement point is located near a station, it is good since a lot of people are passing by. If the location point can not be accessed by anybody, it usually doesn’t matter. But such a place is usually cleaned up frequently, thus the dosage may be lower, however only in the surroundings of the measurement point. There might be higher dosage 20 meters away from the measurement point. When we are told about the values of today’s radiation, we should also know where are the measurement points. If the whole area has not been cleaned up and only some spots were, we cannot use the cleaned up spot as a measurement point.

If someone decides to live in a low radiation place, they should think what is the important place for them. If you almost never go to a station, the radiation measured there is not so important. For you, the important place could be a school, your working place, and so on.

Radiation is not just one kind (What is Sievert?)

If you check an introductory text of chemistry, you notice that the radiation is not just one kind. There are many kinds of radiation: alpha radiation, beta radiation, gamma radiation, neutron radiation, and so on. The different kind of radiation affects differently the human body even at the same absorption dosage (gray in unit). For example, alpha radiation is more dangerous than beta radiation at the same energy level. Therefore, there is a unit called Sievert that adjusts for this difference (Figure 8). It seems scientists agreed that we need some adjustment, but how much adjustment is needed has raised some discussions. For example, how much more dangerous alpha radiation is compare to beta radiation is difficult to determine. This adjustment is called “radiation type weighting factor.” This currently differs from country to country. In Japan, this factor is 20 for alpha radiation, 5 for proton radiation, based on a gamma radiation is value of 1. According to IPRP report 103 (Wikipedia, Sievert), the factor is 20 for alpha radiation, 2 for proton radiation, based on a gamma radiation is value of 1. This coefficient is multiplied by gray to get the value as Sievert. Sievert considers the effect to the human body, but this weighting factor is hard to determine, because this depends on many other factors like person’s age, sex, health status. It is also difficult to make detailed experiments with the human body.

The following analogy is only understandable for someone who likes computer games. But I think this is a good analogy, so I will try to use it here. In many fantasy games, usually a character has some attribute, like fire or water. If a character has a water attribute, he or she can resist more to the water magic. When a character is hit by some fire magic, the damage this character gets depends on his/her fire attribute. At the end, how many health points the character lost is the most important effect. The damage has been adjusted according to the attribute. For radiation there are different types, and the damage to the human body depends on the type. In a similar way, Sievert is an adjusted value of the absorbed energy (gray).

Figure 8. There are many kinds of radiation
Figure 8. There are many kinds of radiation

If a human body gets the same amount of energy but in a different amount of time, the effect of radiation would be different. For example, whether a person gets 10mSv of dosage in a day or in a year it is a different thing, we cannot add yesterday’s radiation dosage and today’s radiation dosage. However, we still have no better measurement than Sievert. It seems Sievert is the best approximation to measure the effect of radiation on the human body. The effect of radiation is not linear, but the Sievert unit assumes that the effect is linear. If you are not familiar with the word `linear’, it is somewhat similar to say that `you can add that up’.

For example, a person cannot eat 500g of salt in an hour, that probably causes death. However, if the same person uses 10g salt per day for 50 days, the danger is drastically less (yet, it still is too much salt). We usually cannot simply add up the amount to difference the effect on a human body.

However, we assume the radiation dosage (Sievert) can be added as an approximation. We should remember that this is an assumption. The Sievert unit is not like the meter unit, which can be added up.

I would like to clarify make clear the difference between 1 mSv/y and 1 mSv since I read many news articles about them. 1 mSv/y means that if you stay at a location where your measured radiation is 1 mSv/y for one year, you get 1 mSv dosage. If you stay in such a location for two years, you get 2 mSv. The current criterion of the evacuation counsel for disasters is 20 mSv/y in Japan (2014). If you stay in a location where you have 20 mSv/y location for five years and assuming that the radiation stays the same, the dosage is 100 mSv. Please notice this difference. If you decide to take the 10 mSv risk, you can only stay at a 1 mSv/y location for 10 years. Especially young children usually have higher risk for the same dosage, so you also need to consider long term exposure. The difference between mSv/y and mSv is similar to you need to pay 1000 Euro every year and you need to pay 1000 Euro only once. Please do not confuse every year payment and one time payment.

We have two criteria that define what is nuclear waste. One is based on the Sievert value, the other is based on the Becquerel value. If the waste consists of one kind of radioactive substance, it is reasonable to define the criterion based on the Becquerel value. Since the half life are depends on the radioactive substance, you cannot really estimate what the danger is if the substance are mixed. Therefore, there are criteria based on each nuclide. However, if many kinds of radioactive substances are mixed up, which is often the case, it is difficult to determine what is nuclear waste and what isn’t. If we can separate all the nuclides, we can still use the Becquerel value criterion separately, however, it is usually not easy to do. In that case, we use a criterion based on radioactive dosage — we use the Sievert value in this case.

If we read a newspaper, it seems that these criteria are used arbitrarily. Sometimes we see a Cesium 137 Becquerel value for cleaning up bi-product waste (e.g., [1]). I wonder if there are other nuclides, for example, is there Strontium 90 in the waste?

Another problem is what kind of radiation can the measurement devices measure. Most of the measurement devices can only measure gamma radiation, but there are other types of radiation.

If you review the periodic table in chemistry, you may notice there are mass numbers in it. For example, there are several kinds of the same element, e.g., Cesium 134, Cesium 137. They are isotopes. These numbers represent their mass number. For example, there are many kinds of radioactive Cesiums. If a newspaper mentions a radioactive Cesium, I would like to know which one it is. Because their half lives differ. The half life of Cesium 134 is around 2 years. The half life of Cesium 137 is around 30 years. This means, the Becquerel value of Cesium 134 becomes 1/1000 after 20 years. On the other hand, the Becquerel value of Cesium 137 becomes only less than half after 20 years. You could learn these things in high school. I found high school science is quite sufficient to know most of these things. I understand that the information sources have only limited time and amount of information they can give. If you know more about this basic chemistry knowledge, you can understand the provided information more.

This is maybe a small detail, the safety criteria of the radioactive waste depend on organizations, countries, and the year [2],[3]. According to Japanese prime minister office (首相官邸)[4], the criterion based on which you should leave an area is when there is more than 20mSv/y. This threshold for the Ukrainian government is 5mSv/y [5]. There is no right and wrong here. Risk is evaluated based on some assumptions and these assumptions differ from government to government. The governments determine these assumptions, therefore, the criteria depend on the country.

In the end, there is always a risk when there is radioactive waste. There is no absolute safety, but there is also an acceptable risk level. Governments usually provide documents about how they consider the risk and what are their assumptions. We need to determine whether we can accept the risk and the assumptions. (Although if a government forces people to accept the risk in some way, or if people cannot decide on their own, I believe this is violation of human rights.) To judge the risk, we first need to understand the information. Then we need to think on our own. The risk is usually probabilistic, we should think through it and decide whether we can accept it or not. If people cannot agree with the government decision, then they should change the government.

The message I’m sending here is to understand this information. This is a first step. It would be not so simple at the end, but the important thing is that we understand the information and we take our decisions on our own.


  1. Kahoku-shinpou (河北新報), The governor of Miyagi-prefecture has accepted for the investigation to build the final disposal repository (宮城県知事、詳細調査受け入れ 最終処分場), http://www.kahoku.co.jp/tohokunews/201408/20140805_11016.html, (Online; accessed 2014-12-26)
  2. Ministry of Health, Labour and Welfare of Japan (厚生労働省), How we handle the radioactive substance in food (食品中の放射性物質への対応), http://www.mhlw.go.jp/shinsai_jouhou/shokuhin.html, 2014, (Online; accessed 2014-12-21(Sun))
  3. Ministry of Health, Labour and Welfare of Japan (厚生労働省), We updated the safety criterion of radioactive substances in food (食品中の放射性物質の新たな基準値を設定しました), http://www.mhlw.go.jp/shinsai_jouhou/dl/leaflet_120329_d.pdf, 2014, (Online; accessed 2014-12-21(Sun))
  4. Prime Minister’s Official Residence (首相官邸), Keeping everyone’s safety (みなさまの安全確保) http://www.kantei.go.jp/saigai/anzen.html/, How we set up “the planned evacuation region” and “preparation necessary region when the emergency “(「計画的避難区域」及び「緊急時避難準備区域」の設定について), http://www.meti.go.jp/press/2011/04/20110422004/20110422004-2.pdf, 2011, (Online; accessed 2014-12-21(Sun))
  5. オレグ・ナスビット, 今中哲二, ウクライナでの事故への法的取り組み, http://www.rri.kyoto-u.ac.jp/NSRG/Chernobyl/saigai/Nas95-J.html, 2011, (Online; accessed 2014-12-21(Sun))


最終処分の話をしようや (8): 付録 2: 放射能・放射線について

Radioactivity and radiation

If you check Wikipedia or any chemistry course, you have some idea of what is an atom, what is radiation, what is radioactivity, and so on. Why is radiation dangerous? Because it can break the DNA in our body and that makes you sick. How much does it can break depends on the radiation energy, on how much energy our body absorbed and so on. In a way, it depends on how strong the offense is and how strong the defense is. To know more about this, first we should know about the concept of radioactivity, radiation, and their strength. Since we don’t know the meaning of those things, we are left with trusts the authorities on these matters. I would like to avoid such situation. Here I summarize the meaning of radioactivity, radiation, Becquerel, Sievert, and so forth.

We can use an analogy with light to think about these substances.

An analogy between a light bulb and radioactivity
Figure 6: An analogy between a light bulb and radioactivity

Radioactivity is also known as radioactive decay or nuclear decay. It is the process of a nucleus of an unstable atom losing energy by emitting radiation to move to a more stable state. If an atom can emit radiation, it is considered radioactive. From an observer point of view, saying that something is radioactive means that a substance can emit radiation. It is an ability of emitting radiation. If you think about a model with an offense and a defense, this is the offense side. If you think about this as light, a light bulb has the ability to emit light, so I could say that a light bulb is light-active. In this analogy, the emitted light is itself radiation. Figure 6 shows how a light bulb and a radioactive emitter that correspond to each other. Radioactivity is more like a property of a substance, that is similar to the property of a light bulb. Please note, radioactivity does not correspond to emitted light, but rather to a light bulb. A light bulb has the ability to emit light, but a light but is not light per se. We can grab a light bulb and move it to a box, then we can take it out from the box, but we cannot grab light and put it in a box. We can also use the analogy of sound. A speaker has the ability to create sound, so we could say it is sound-active, but, the speaker itself is not sound. I hope by now you know the difference between radioactivity and radiation.

Radiation is the emission of energy from the nucleus. When a nucleus changes the state, an emission happens. What kind of radiation will be emitted depends on the type of nucleus. The unit this quantifies how many times the decay happens in a second per a certain unit mass is called Becquerel (Bq). This is the strength of the offense side as we were saying earlier. A certain unit mass means for example 1kg or 1t, it is just some amount of mass.

Why do we need a certain unit of mass? Because even if we only have the same Bq radioactive substance, when we have more of it, the number of decay events increases. It is same as saying that if we have more light bulbs switched on, we get more light. Therefore, usually we see this amount of number of decay per kg (Bq/kg). If 1kg of radioactive waste is 8000 Bq it means that this 1kg of radioactive waste has 8000 decays per second. If there is 2kg of this waste, you observe 16000 decays per second. When the number of decays per second (Bq) increases, the corresponding radiation energy will also be increased. However the Bq/kg in this example is the same in both cases, that is 8000 Bq/kg. If an article only said Bq without ‘/kg’, then that should be the number of decay per second. If the certain unit of mass is smaller, then the number becomes smaller even if radioactivity stays the same. 8000Bq/kg is equal to 8Bq/g. If some food has 1000 cal/kg, it is the same as 1 cal/g. Please be careful with units.

Sometimes a criterion is defined on Bq/kg. For instance, a safety criterion defines that water is safe if it is less than 10Bq/kg. Personally, I have a problem with this criterion. Since you can add non-contaminated substances to mix with contaminated waste, you can fulfill this criterion. For example, if you have a 1kg 8000Bq/kg waste, if you mix it with a clean 1kg substance you have 2kg 4000Bq/kg waste. If you have high Bq/kg tritium water, you can just put more water and achieve low enough waste water that allows to throw it in the sea according to this criterion. If any poisonous substance has this density criterion (which sometimes make sense), we could put it in the sea and pass this safety criterion. Do you think we can continue with that? I find this is dangerous. For me this density criterion (Bq/kg) is questionable. At least I would like to know how much is the absolute value, like some “8000Bq/kg waste 10kg was trashed.” If you understand this unit (Bq/kg), I think you know what kind of information you would like to know more. If I only have the Bq/kg, I see that the information — How much waste have you actually trashed? — is hidden away.

An analogy between light and radiation
Figure 7: An analogy between light and radiation

Amount of radiation (energy)

By now, you see that the real danger is radiation rather than radioactivity. We cannot switch off radioactive substances in order not to emit radiation. (On the other hand, we can switch off a light bulb in order not to emit light.) Thus, radioactive substances are of course dangerous. But, we could block or weaken the radiation from radioactive waste if we can put it in a thick container of lead. Therefore, if radioactive waste is well under control, we can stop the radiation. Then there is no harm to life. The problem is not like in a situation, where some radioactive substance is dispersed in the environment. In that case, how much radiation is emitted is important.

A dosage shows how much radiation is there. To say that more exactly, a dosage shows how much radiation is absorbed by something. But we could think about this as first how much radiation is there and then how much that affect a person. Figure 7 shows an analogy between light and radiation. If you go away from the light source, the brightness your receive (irradiance) becomes lower, which means it gets darker. In that Figure you see two kind of units. For radiation, we consider the energy absorption instead of radiation energy itself. You see two kind of units, Gy (gray) and Sv (Sievert). Why do we consider the energy absorption? Because if a human body is exposed to the same radiation energy, the effect also depends on how much radiation energy was absorbed by the body. For a measurement about safety, the amount of absorption is important. We measure how much energy is absorbed by gray (Gy). It is defined as the absorption of 1J of radiation energy per 1kg of matter. (If you don’t know about what is 1J, Please look up what it is.) You can imagine that thinking of the amount of energy absorption is similar to thinking of how much damage you got.

If you play some role playing video games, you know the damage depends on what is your armor or how you got the damage. That is represented by decreased your health points. In these games, what is important is how many health points you lost, not how strong the attacker is. The amount of absorption for radiation is like the amount of decreased the health points. But actually the most important value is the remaining health points, not their past decrements. However, the remaining health points for radiation depend on the person, age, and so forth. There is no simple criterion for safety, but the amount of absorbed energy could be one of such criteria.

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