最終処分の話をしようや (2): 最終処分とは? 放射性廃棄物とは?

The final disposal of nuclear waste consists in storing the waste until its radioactivity becomes low enough to not affect the environment. We first talk about what kind of nuclear waste there is, then what the sources of the waste are, and then how we manage them.

What is nuclear waste?

There are two criteria to define whether some waste is nuclear waste or not. The first one is based on measuring the amount of radiation that is absorbed in a certain amount of time (10 mSv/y), the second one is based on the amount of emitted radiation (radioactivity, Bq). Both have thresholds that used to define whether something is nuclear waste or not. If some specific waste goes over either one of two thresholds, it is classified as nuclear waste. One other point here is if a waste is less than this criteria even the waste has some radioactivity, such waste can be recycled in the market.

Yamauchi’s memorandum

Previously, I had the misconception that all the waste which is radioactive and which is produced by nuclear reactors is nuclear waste. However, there is a criterion that defines what nuclear waste is. In a later section, I extended my memo about the meaning of the criterion. For instance, what is Sievert and what is Becquerel, and what is the difference between radioactivity and radiation.

Classification of nuclear waste

Nuclear waste is classified in the following three categories:

  • High level (TRU waste, used nuclear fuel)
  • Middle level (This waste is rare)
  • Low level

Germany’s classification is based on how much heat the waste generates since it is important for the waste management. TRU waste consists of TRans-Uranium elements whose atomic number is higher than Uranium. TRU waste is usually generated by a running reactor.

Source of nuclear waste

The sources of high level nuclear waste (+TRU waste) are:

  • Used nuclear fuel
  • Waste liquid by reprocessing, vitrified waste
  • etc. …

The sources of low and middle level nuclear waste are:

  • Nuclear power plant
  • Decommissioning process
  • Nuclear fuel fabrication facility
  • Used nuclear fuel reprocessing plant
  • (uranium mine, enrichment plant)(mining field)
  • Medical institution
  • Industrial factory
  • Research and development institutions, miscellaneous

A nuclear power plant always produces nuclear waste regardless of whether the reactors are running or not, because of the maintenance process. For example, the clothes of the workers will become irradiated even if the reactor is not active. Hospitals and some industry are also sources since they use radioactive materials.

All nuclear waste is managed as dangerous substances by law in Germany. On the other hand, the last three items are not managed as dangerous substances in Japan. Therefore, we do not know how some nuclear waste is transported or preserved in Japan.

Yamauchi’s memorandum

In my personal opinion, Japan should also handle the last three items as dangerous substances as in Germany. This is to ensure control of these types of radioactive waste.

The classification as nuclear waste should depends on whether the radiation dose is more than 10mSv/y or not. If the radiation dose is less than 10mSv/y, we can recycle the waste in the public market. However, this threshold (10mSv/y) does not really tell whether this is safe or not. I would like to notice that by this criterion, safety is unclear. Also according to this definition, we can recycle a steel with 9.9mSv/y radiation dose to build a house or household items. This is legal. If you search with keywords “steel radioactive waste recycle”, you can find some information. However, many of the cases could be completely legal. In this article, I do not discuss the safety of this clearance criterion since the safety of radioactive waste is difficult to discuss. The best way is just to avoid it. But I would like to point out that some waste which is pass this criterion can be legally in our market.

最終処分の話をしようや (1): 核のゴミの現状: なぜ最終処分の話なのでしょうか?

In our last meeting “Let’s talk about nuclear decommissioning,” we realized the nuclear decommissioning produces nuclear waste. But we did not talk about what do we do about the nuclear waste. A nuclear decommissioning is about what do we do for a reactor after its lifespan ended or cannot use the reactor anymore when it is broken by any reason (e.g., an accident). What we learned was that a decommissioning costs money (e.g., 1 billion dollar/reactor) and time (e.g., 30 years). Even then the decommissioning has finished, the nuclear waste still remains. The last meeting ended here. Then some of our members asked: “What do we do about the nuclear waste?” “How much does they cost?” “Who need to pay that?” “What is the current plan?”

The members of SNB (Sayonara Nukes Berlin) originally asked both questions: nuclear decommissioning and nuclear waste management. However, two and half hours were not enough to talk about both themes. So, we have this second meeting.

Let's talk about nuclear waste: A meeting snapshot
Let’s talk about nuclear waste: A meeting snapshot


There are two parts alternately in this report: Fukumoto’s lecture and Yamauchi’s memorandum. Yamauchi’s memorandum is the part of how the reporter understood.


In the first meeting, Fukumoto pointed out the importance of “think through what I can do as a citizen,” when anyone thinks about the energy problem. He would like to add one more point in this meeting:

After the Fukushima incident, we had blackout days. When the power companies explained that this is because we do not have nuclear reactors running. Can you still be against the nuclear reactor? Please think through this once more.

He mentioned the importance of thinking about the problem first and having an opinion. It is important to understand the problem yourself and also important to find the information by yourself. It does not matter whether you are in favor of the reactor or against the reactor. But you need to find the correct information and you need to think about the problem based on that information.

Yamauchi’s memorandum

The sections of Yamauchi’s memorandum shows the reporter’s opinion and research; how we think in the current situation, how we think about our future. Under our current political system, these ideas will be shown in the vote. After the meeting, I reconsider this.

What I thought was that: Do I want to have a future with nuclear reactors? Do I agree with the nuclear reactors because the electric company said they are needed. Do I disagree with the nuclear reactors if the electricity is enough? I thought first I needed a clear vision for our future. The vision should not depend on whether the current electricity is enough or not. The reality would have some compromises, but the vision should not. I would like to think about what I could do, or what each of us could do for our future. Of course this also includes the near future, tomorrow. Shall I make a compromise tomorrow? Another idea is that there is no future without tomorrow. So we could put the highest priority on tomorrow. It is not a simple problem. Still I think I should have a clear vision for the future. Because we and our children will live in that future. In my personal opinion, I could not agree with the idea that now is important enough, so that we can destroy the future.

We see a lot of potential in our technology. I understand that we cannot stop using electricity now. However, we have some technology that generates sustainable energy. For example, a combination of solar energy and hydrogen energy, we might have a stable energy source. We could develop a technology to produce this energy at low cost in the future. Investing in such technology is also a way of working on the future. One day we could export such technology to the people who need all over the world.

We also have a lot of possibility in politics. We can provide a way to only buy natural energy for the people who want this. This means we can also provide a way to only sell nuclear energy to the people who want it. I see that the current problem in Japan is that the people cannot choose in either way. (There is an official plan to make this possible.) We can work on these political problems together.

In the end, I need to have my own opinion based on the current situation. It will be cumbersome, it will be hard, but I need to understand the current situation. I hope this report is of use to someone who would like to understand the current situation.

We tend to avoid the politics, we can leave it alone. But politics will catch you. — Richard Stallman.