Domestic nuclear power plants are stipulated to have a maximum operating period of 60 years, but the government is considering allowing for further extension.
Behind this is a policy of maximizing the use of existing nuclear power plants in order to realize a decarbonized society and a stable supply of energy.
But how many nuclear power plants are still in operation?
Is there any safety issue with driving for such a long time?
As I answer these questions, I will explain in detail.
Steadily restarting nuclear power plants, more towards next summer
There are currently 15 nuclear power plants and 33 nuclear power plants in Japan.
Of these, 10 reactors at 6 nuclear power plants have passed the review of the Nuclear Regulation Authority and have restarted operations.
The breakdown is:
▽Kansai Electric Power's Takahama Nuclear Power Station Units 3 and 4, both in Fukui Prefecture
▽Oi Nuclear Power Station Units 3 and 4, Mihama Nuclear Power Station Unit 3
▽Kyushu Electric Power's Sendai Nuclear Power Station Unit 1 in Kagoshima Prefecture and Unit 2
▽ Units 3 and 4 of Kyushu Electric Power's Genkai Nuclear Power Plant in Saga Prefecture ▽ Unit 3
of Shikoku Electric Power's Ikata Nuclear Power Plant in Ehime Prefecture.
Furthermore, in order to realize a decarbonized society and provide a stable supply of energy, the government has indicated that it will aim to restart the operation of the five nuclear power plants, which have already passed the review by the regulatory committee, from the summer of next year. .
▽Tohoku Electric Power Co., Ltd.'s Onagawa Nuclear Power Station Unit 2 in Miyagi Prefecture
, ▽
TEPCO's Kashiwazaki-Kariwa Nuclear Power Station Units 6 and 7 in Niigata Prefecture,
▽Japan Atomic Power Company's Tokai Daini Nuclear Power Station in Ibaraki Prefecture, and
Fukui Prefecture. Units 1 and 2 of the Kansai Electric Power Takahama Nuclear Power Plant
▽ Chugoku Electric Power Shimane Nuclear Power Plant Unit 2 in Shimane Prefecture.
Under these circumstances, the “maximum utilization of nuclear power plants” is under consideration.
By FY2030, the government aims to increase the proportion of nuclear power plants, which do not emit carbon dioxide during power generation, to about 20 to 22%, which is about 4% to 5 times the FY2020 level.
However, even if all nuclear power plants, including those under construction, operate, if the upper limit of the operating period remains 60 years, it will decrease significantly in the 2040s, and will drop to about 10% in 2050. .
The government plans to consider the development and construction of next-generation nuclear reactors, but the outlook for commercialization is the mid-2030s at the earliest, and construction may take even longer.
In light of this situation, the government hopes to compile concrete measures such as the development of legislation necessary for further long-term operation of nuclear power plants by the end of the year.
Half of them have been in operation for over 30 years
On the other hand, what really worries me is safety.
In fact, 17 of the 33 nuclear power plants in Japan have been in operation for over 30 years, and 4 reactors at 3 have been in operation for over 40 years.
There is also a risk of aging due to long-term operation
When nuclear power plants are operated for a long period of time, various equipment and facilities deteriorate due to the effects of radiation and heat.
In 2004, there was a pipe breakage accident at Kansai Electric Power's Mihama Nuclear Power Station Unit 3 in Fukui Prefecture, and five workers were killed by the steam that spewed out.
The cause of the broken pipe was that it had not been inspected since the start of operation.
In addition, steel reactors lose strength due to neutrons generated by nuclear fission, metal pipes become thinner due to erosion and corrosion due to hot water and steam flowing inside, and cables lose their performance due to heat. Decrease.
Concrete structures may also lose strength due to heat and radiation.
In order to deal with these risks, electric power companies are still obliged to assess whether important facilities can be used safely before 30 years have passed since the start of operation, and to create a management plan and update it every 10 years. It is
In addition to that, if you want to operate for more than 40 years, you need to conduct a "special inspection" to examine the state of deterioration in detail and apply to the regulatory committee for review. is allowed.
Extension of operation period How to ensure safety?
In response to the government's consideration of extending the operating period of nuclear power plants, the Nuclear Regulation Authority has started to create a system to ensure safety even when operating beyond 60 years. .
At the meeting on the 2nd, the secretariat, the Nuclear Regulation Authority, made it obligatory to confirm the deterioration status every 30 to 10 years after the start of operation, formulate a management plan, and obtain approval from the NRA. In addition, the period during which the operation is stopped should be included in this period, and in order to cope with the fact that the design itself will be outdated, it will be necessary to comply with the latest standards. it was done.
Going forward, the Regulatory Commission will compile a framework for the system by the end of the year after listening to the opinions of electric power companies.
The proposal presented this time is a combination of safety evaluations every 10 years and "special inspections" that are conducted in the examination of operation over 40 years, and will not exceed 10 years after 30 years since the start of operation. We are obliged to confirm the deterioration status for each period, formulate a management plan, and obtain approval from the regulatory committee.
Furthermore, it was also included to confirm compliance with the latest standards, even considering the deterioration of equipment and facilities.
Nuclear Regulation Authority Chairman Yamanaka "Regulations are much stricter than the current system"
Shinsuke Yamanaka, Chairman of the Nuclear Regulation
Authority, said, "After 30 years from the start of operation, the idea is to redesign the rule so that if it meets the standards every 10 years at the maximum, it will be approved, and if it does not meet the standards, the operation will be stopped at that point. It is difficult for businesses to prove that they are required to repeatedly seek approval every 10 years or less, so we recognize that the regulations will be much stricter than the current system.”
the situation abroad
According to the summary of the IAEA = International Atomic Energy Agency, as of the end of last month, 66% of the world's 427 nuclear power plants have been operating for more than 30 years, 283, and 30% have exceeded 40 years. It is 128 bases.
The longest one is Beznau nuclear power plant No. 1 in Switzerland and Nine Mile Point nuclear power plant No. 1 in the United States, which started operation in 1969, 53 years ago.
In the United States, the operating period is stipulated to be 40 years, but it is not for technical reasons, but from the perspective of prohibiting monopoly of the public utility business. and there is no limit to the number of extensions.
According to the Agency for Natural Resources and Energy, there are 94 nuclear power plants that have been allowed to operate for over 60 years, and 6 of them have been allowed to operate for over 80 years.
However, old nuclear power plants are being decommissioned one after another from an economic point of view, and it is up to the electric power company to decide whether they will actually continue to operate for more than 60 years.
In France and the UK, there is no limit on the operating period, and it is a system to be reviewed every 10 years.In France, 20 out of 56 nuclear power plants have been in operation for more than 40 years. That's it.
Former Chairman of the Nuclear Regulation Authority Fuketa "The situation in Japan and overseas is different"
On the other hand, Mr. Toyoshi Fuketa, former chairman of the Nuclear Regulation Authority, commented on such overseas cases, saying, "Even if there is only one earthquake, the situation in Japan and overseas is completely different, and new knowledge has raised earthquake resistance requirements. There are also cases where the situation in Japan is different, so it is not necessarily possible to directly refer to cases overseas," he said, expressing the view that a mechanism that matches the situation in Japan is necessary.
Expert: "It is necessary to make individual judgments for each furnace"
Professor Hiroshi Yamagata of the Nagaoka University of Technology, a former executive of the Nuclear Regulation Authority, commented on the risks of long-term operation of nuclear power plants: The most worrisome problem is that the reactor pressure vessel, where the core is located, becomes fragile due to the neutrons hitting it, and since it changes depending on how the reactor is operated, it is necessary to make individual judgments for each reactor." I was.
Regarding the system proposal presented on the 2nd, he said, ``Since there was no technical basis for the 40-year term, it is acceptable to approve every 10 years after 30 years until safety is ensured. Otherwise, we can make a technical decision not to admit it, so I think it makes sense."
After that, he said, "It becomes difficult to evaluate how much deterioration progresses with each passing year.In that situation, I think it will be a tough job because the regulatory committee must decide whether to continue operating the nuclear power plant." rice field.