The biggest nuclear power plant in the world has been vulnerable to unauthorized entry at around a dozen areas since March last year, with its security system only partially working and some backup measures also not functioning, Japan’s nuclear regulators said Tuesday.

Intruder detection systems were defective at 15 places at the Kashiwazaki-Kariwa plant in Niigata Prefecture, according to operator Tokyo Electric Power Company Holdings, aka Tepco. The Nuclear Regulation Authority said backup systems were insufficient in 10 of the locations.

The NRA has provisionally rated the breach at the worst level in terms of safety lapses — the first time it has given such a lousy grade. The NRA chief said that further probes will take “a year or more” and suggested the plant’s application to restart could not be processed until they conclude. Penalties will be discussed after the rating is finalized.

Nuclear Regulation Authority says 'most serious level' lapse as Kashiwazaki-Kariwa nuclear power plant unable to detect unauthorized intruders [Japanese] | FNN PRIME ONLINE
Nuclear Regulation Authority says ‘most serious level’ lapse as Kashiwazaki-Kariwa nuclear power plant unable to detect unauthorized intruders [Japanese] | FNN PRIME ONLINE

The past month hasn’t been kind to Tepco. Weeks before the 10th anniversary of the Fukushima disaster, the Tokyo High Court ordered the government and Tepco, which operated the Fukushima No. 1 plant, to pay damages to those who had to evacuate due to the crisis, overturning a decision that dismissed the state’s responsibility for the meltdowns.

But the news hasn’t all been bad for Japan’s nuclear industry in 2021. On Feb. 1, the mayor of Takahama in Fukui granted permission for the restart of two reactors at Kansai Electric Power’s plant in the town, becoming the first local leader in Japan to OK the use of reactors aged older than 40 years, reports Eric Johnston.

Speaking with Bloomberg ahead of March 11, Tepco chief Tomoaki Kobayakawa said that Japan’s biggest utility will need to rely partly on atomic energy to meet its pledge to cut carbon emissions in half by 2030. He also told Kyodo, “Ultimately, it is we, the operators, who ensure the safety” of nuclear plants. Trust will be regained “only after society recognizes what we have achieved.”