13 years after the Fukushima Daiichi nuclear power plant accident, there is uncertainty about the plan to decommission the reactor in up to 40 years

13 years have passed since the world's worst accident at the Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Plant.

While the much-anticipated release of treated water has begun, most processes, including the removal of melted nuclear fuel debris, have been forced to be postponed, and plans to complete decommissioning in up to 40 years are becoming uncertain. It is increasing.

The Fukushima Daiichi Nuclear Power Plant lost power due to the huge earthquake and tsunami caused by the Great East Japan Earthquake 13 years ago, causing a "meltdown" in which nuclear fuel melted away in three operating reactors, resulting in a large amount of radioactive material. was released.

Nuclear fuel debris, which is the melted nuclear fuel from Units 1 to 3 mixed with surrounding structures, is estimated to total approximately 880 tons, and the amount continues to increase as water used for cooling and underground water becomes contaminated water. I am.

The treated water containing radioactive substances such as tritium that remains after treatment of this contaminated water is stored in over 1,000 tanks, and its disposal has been a concern, but in August last year, TEPCO decided to comply with government policy. After diluting the concentration to below standards, they began releasing it into the ocean.

However, China's countermeasures against imports of Japanese seafood products are still in effect, more than half a year later, and the impact is lasting.

In addition, in the process of treating contaminated water, a worker was temporarily hospitalized after being exposed to waste fluid containing radioactive materials in October last year, and on the 7th of last month, there was a problem with water containing radioactive materials leaking from a purification system, causing local residents to Fukushima Prefecture and other countries are paying strict attention to TEPCO's safety management.

On the other hand, regarding the removal of "nuclear fuel debris", which is considered the biggest hurdle in decommissioning, the plan was to begin trial removal from Unit 2 by the end of this fiscal year, but the installation of equipment did not progress and the I gave up on the month.

We are once again aiming to start by October this year, but this is the third time that the start of extraction has been postponed, and it will be nearly three years behind the original plan.

In addition, while there is no prospect that full-scale removal, which is scheduled to begin at Unit 3, will begin, on the 8th of this month, a national specialized agency announced that it will be pouring filler into the reactor and other parts of the reactor to remove debris. We recommended that a new construction method be used in some areas, which involves solidifying the entire material and then removing it.

TEPCO has said that it will examine feasibility over the next one to two years, but Toyoshi Fuketa, former chairman of the Nuclear Regulation Authority, who compiled the recommendations, said, "If you think about it, we can't afford to stand still forever, so I'm proposing that this is a turning point," he said, adding that the plan to complete decommissioning in up to 40 years is becoming increasingly uncertain.

Contaminated water treatment causes trouble; local residents ``very disappointed''

Regarding the treated water that contains radioactive substances such as tritium that remains after treating contaminated water, the government says that ``disposal is unavoidable in order to move forward with decommissioning'' and mixes it with a large amount of seawater to dilute it to a concentration below standards. At that time, we decided to release the waste into the ocean, and the release into the ocean began in August last year.

Amid strong opposition from fishermen and others concerned about reputational damage, the government decided to release the contaminated water after gaining a certain level of understanding to ensure safety and prevent harmful rumors. I'm having troubles one after another with the work I'm doing.

Last October, a hose came off while cleaning pipes at a contaminated water treatment facility, spraying waste fluid containing radioactive materials on workers, and two men were temporarily hospitalized with contamination on their skin.

Additionally, on the 7th of last month, workers at another purification system failed to notice that the valves of some of the pipes were open, causing water containing radioactive materials to leak outdoors. It leaked out.

In both cases, it is said that no impact of radioactive materials on the outside of the nuclear power plant has been confirmed, but residents of the local Fukushima Prefecture say, ``Troubles are occurring frequently and the situation is not safe,'' and ``The treated water is in the ocean. There are voices of anxiety and concern, such as, ``It's very disappointing given the worldwide attention and scrutiny regarding the release.''

Decommissioning roadmap Current status [Details]

Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Plant continues with the aim of completing it by 2051, 40 years after the accident, but the biggest hurdle is removing the melted "nuclear fuel debris". Initially, most of the processes were delayed from the original plan, and it is becoming increasingly uncertain whether the decommissioning will be completed as planned.

In 2011, when the Fukushima Daiichi Nuclear Power Plant accident occurred, the government and TEPCO took measures to deal with contaminated water generated in the reactor building, transport and storage of spent nuclear fuel remaining in the reactor building, and measures to remove melted nuclear fuel. A roadmap was established to complete the decommissioning process in 30 to 40 years by proceeding step by step with efforts to remove nuclear fuel debris mixed with surrounding structures.

Regarding countermeasures against contaminated water, we initially aimed to reduce the amount generated to zero, but due to the fact that the damage to the building was more severe than expected, we were unable to stop the inflow of rainwater and groundwater, and even now we continue to do so every day. This is occurring at a rate of approximately 90 tons.

On the premises, the number of tanks that store treated water from which most of the radioactive materials have been removed from contaminated water continues to increase, and the government decided that it could not continue to store water as it was, so in August of last year, it mixed a large amount of seawater with the treated water to reduce the concentration below standards. After diluting the water, we began releasing it into the ocean.

In addition, over 1,000 spent nuclear fuel remains in the pool on the top floor of the reactor building, including Units 1 and 2, and the goal of completing the removal to the storage facility is 10 years from the original plan. The date has been delayed to 2031.

Meanwhile, the nuclear fuel debris that melted down from Units 1 to 3 is estimated to total approximately 880 tons, and the plan was to begin removing it by 2021.

However, the trial extraction scheduled for Unit 2 has been repeatedly postponed due to lack of progress in installing equipment, and the full-scale extraction scheduled to begin at Unit 3 has not yet been determined, and there is no prospect that it will be able to begin. yeah.

Under these circumstances, on the 8th of this month, a national specialized agency recommended that a new method be used in part to prepare for full-scale retrieval, in which filler is poured into nuclear reactors, solidified together with debris, and removed. The company plans to conduct feasibility studies over the next one to two years.

Most of the major steps have been forced to be reviewed or postponed, and the decommissioning roadmap has been revised five times by 2019.

The realization of the plan to decommission the reactor in up to 40 years is becoming increasingly uncertain, but the government and Tokyo Electric Power Company are currently sticking to their goal.

Akira Ono, CEO of TEPCO's Fukushima Daiichi Decommissioning Promotion Company, said in an interview with NHK, ``There is no need to review the 40-year target at this point, and we don't have the materials to discuss a review yet. It is important to reduce the risk of radioactive materials safely, steadily, and as quickly as possible for reactors, and the reality is that while various tasks are confusing, we have decided on priorities and worked on them.If we do not have a goal, we will not be able to decommission the reactor. There are concerns that we will be slowing down in our efforts to achieve this goal, so a goal of 30 to 40 years is of great significance."