Group Intro: The Group of Citizens Seeking a Court Decision Ordering the Decommissioning of Nuclear Power Plants Over 40 Years Old
By Shibayama Yasuko (Secretary General, Group of Citizens Seeking a Court Decision Ordering the Decommissioning of Nuclear Power Plants Over 40 Years Old)
We, the Group of Citizens Seeking a Court Decision Ordering the Decommissioning of Nuclear Power Plants Over 40 Years Old, are the plaintiffs and supporting citizens fighting a lawsuit to overturn the government-approved prolonged operation of Kansai Electric Power Company’s Takahama NPP Units 1 and 2 and Mihama NPP Unit 3, all in Fukui Prefecture. We brought this suit to the Nagoya District Court in 2016. The defendant is the Japanese government (the Nuclear Regulation Authority is the administrative agency). We have 600 members. Our secretariat is placed in Nagoya, but we have members nationwide, including residents of NPP-hosting Takahama Town and Mihama Town and other areas in Fukui Prefecture, and also in the Kansai and Chubu areas. The plaintiffs also include evacuees who were forced to relocate after the March 11, 2011 Tokyo Electric Power Company’s Fukushima Daiichi NPS disaster. They say that no other people should have to suffer the same damage they unavoidably experienced.
TEPCO Fukushima Daiichi NPS Unit 1, which melted down first amidst the disaster, was scheduled to turn 40 years old on March 26, 2011. The detailed causes of the disaster are still yet to be fully investigated, but the obsolescence of the plant model and the aging of the facilities have been pointed out as possible causes.
Based on the lessons learned from the TEPCO disaster, the legislation was established stating that 40-year-old nuclear reactors should be decommissioned. The law limits the service life of a nuclear reactor to 40 years as a rule; however, at the same time it permits a 40-year-old nuclear plant to run for another 20 years “in the most exceptional case among exceptional cases” (the exact wording by the government). This exceptional 20-year extension rule was first applied to Takahama Units 1 and 2, and then to Mihama Unit 3. Thereafter, all the aged reactors that have applied for the 20-year life extension have been approved. The “exception” now seems to have become the “rule.”
Takahama Unit 1 has operated for more than 50 years since it first came online. Its reactor pressure vessel (RPV), which is the most important component of a reactor, tops all other reactors in Japan in the progress of neutron irradiation embrittlement (RPV steel embrittlement due to exposure to neutrons for many years). If an earthquake or other unusual event occurs and cooling water fails to reach the reactor pressure vessel (RPV) due to a pipe rupture or otherwise, the emergency core cooling system (ECCS) is activated and a large volume of cooling water is rapidly poured into the RPV. If the RPV has any cracks, these cracks will be forced to expand, and the embrittled RPV may be damaged. To prevent this, the regulations make it a rule to check current embrittlement by assessing monitoring sample bars in the reactor to predict future embrittlement. However, the bars do not provide sufficient data. Furthermore, it was found that the Nuclear Regulation Authority failed to check the data. The sample evaluation method had many problems, underestimating the degree of embrittlement. We clarified these problems comprehensively in court.
The court proceedings took time, but new and important data was disclosed during the proceedings, backing the soundness of our arguments. The monitoring data for actual nuclear facilities presented by the Secretariat of the Nuclear Regulation Authority was found to have errors in the embrittlement prediction. It was learned that, according to the correct evaluation, Takahama Unit 1 is severely embrittled and the RV can be damaged even at present whenever the ECCS may be activated. Details are shown in the CNIC article cnic.jp/59821 (in Japanese).
To present such scientific and technological arguments, we requested an investigation by the experts of the Citizens’ Nuclear Information Center and the Research Group on the Problem of Aging of Nuclear Power Plants. The arguments were submitted in writing and given orally in court. We appreciate the great support we have received from these organizations.
However, to our regret, on March 14, 2025, the Nagoya District Court dismissed our complaint. The reasoning was that as far as the latest actual nuclear facility data is concerned, while the evaluation method is questionable, there is no expert knowledge that is capable of denying the precision of the conventional method.
While we, the plaintiffs, demonstrated the evidence regarding the latest actual nuclear facility data based on expert knowledge, the witnesses for the defendant avoided giving any judgement concerning the data given in evidence. We argued that, if in doubt, the court should judge in favor of safety, namely, should stand on the conservative side in consideration of knowledge that foresees danger. However, the Nagoya District Court “stood on the side of operating the aged reactors whose safety is in doubt.”
Similarly, for other points of arguments, such as earthquake and volcano impact evaluation as well as the issue of the handling of spent nuclear fuel, the court made a judgement in favor of the defendant.
Of course, we will never give up. We have appealed to the Nagoya High Court. We will continue to fight for the decommissioning of aged reactors as soon as possible, and we appreciate your continued support and cooperation.
