Japan’s ageing Mihama 3 reactor restarts

24 June 2021

Japan’s Kansai Electric Power Co on 23 June began operating unit 3 at Mihama NPP in Fukui Prefecture for the first time in some 10 years, after completing final inspections. The reactor was taken offline after the 2011 Fukushima accident. Mihama 3 will be the first nuclear unit to operate beyond the government-mandated 40-year service period introduced under post Fukushima rules.

However, the unit, which began commercial operation in 1976, is expected to be halted again in about four months before the 25 October deadline for the implementation of counterterrorism measures which Kansai Electric says it is unlikely to meet. The Nuclear Regulation Authority (NRA) granted approval in 2016 for the reactor to operate beyond the 40-year limit for an additional period of up to 20 years, after screening the company’s safety measures for the unit. In February, Mihama Mayor Hideki Toshima approved the restart as did Fukui Governor Tatsuji Sugimoto in April despite some concern among local residents.

On 21 June, a group of nine people in Fukui as well as neighbouring Kyoto and Shiga prefectures filed a lawsuit with the Osaka District Court, seeking suspension of Mihama 3. They argued that ageing reactors are prone to accidents in the event of a massive earthquake and that the 40-year operation period should be strictly applied in Japan, which could be hit by a natural disaster anytime.

Tatsujiro Suzuki, a former deputy chairman of the Cabinet Office's Atomic Energy Commission, who is also on the advisory board of a parliamentary committee on nuclear safety, told Reuters that he has misgivings over how approval for the restart was obtained. He said he was concerned about a lack of transparency and the use of subsidies to sweeten local opinion to get the necessary restart approval. "It looks like the industry and the government have not learned the lessons of Fukushima," he said.

Frequent visits to Fukui by officials, including the head of the natural resources agency, were mentioned at a recent hearing of the parliamentary committee. A subsidy of JPY2.5 billion ($23 million) was agreed for local communities before the Fukui governor signed off on the Mihama restart, Reuters said.

The Ministry of Economy, Trade and Industry (METI) said in response to emailed queries from Reuters that it had decided on the subsidies in April this year and had informed local officials in Fukui. METI confirmed the number of visits by officials to Fukui and said the trips were "to exchange opinions".

Kiyoshi Kurokawa, who headed a major investigation into the Fukushima accident said it was an avoidable "man-made" disaster in his 2012 report. "It's always important to ask what are the sanctions for bad corporate behaviour. If there are none, and in Japan there are none, then oversight is meaningless," he said, adding he was "concerned" about the Mihama restart.

Units 1&2 at the Mihama plant were permanently closed in April 2015 in line with the 40-year limit. However, two other Kansai Electric reactors in Fukui Prefecture, Takahama 1&2, have also secured NRA approval and local consent to operate beyond 40 years. However, they will not resume operation in the near future as Kansai failed to meet a 9 June deadline to complete the implementation of counterterrorism measures.

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