A Japanese court on 12 March rejected a request to units 3&4 at Kyushu Electric Power Co’s Genkai NPP in Saga Prefecture. The plaintiffs, including people living near the plant, had demanded that the utility halt operation of the units amid safety concerns.

However, the rulings by the Saga District Court "recognised that strict examinations were made based on new (safety) standards formulated after the nuclear accident at Tepco's Fukushima Daiichi power plant," the Nuclear Regulation Authority's (NRA’s) secretariat said.

The most contentious point in the cases was whether NRA and Kyushu Electric had underestimated the standard ground motion, or maximum shaking that a reactor could withstand during a possible earthquake, a key factor in its quake-resistance design.

The plaintiffs are expected to appeal against both rulings. In a similar case in December 2020, the Osaka District Court had revoked government approval of the operation of units 3&4 of Kansai Electric Power Co's Ohi NPP in Fukui Prefecture. This was the first ruling by a Japanese court rescinding government approval granted to a utility to operate a nuclear plant under the more stringent safety standards introduced in 2013 following the meltdowns at the Fukushima Daiichi NPP in March 2011.

In the run-up to latest ruling, the Saga District Court and the Fukuoka High Court had both rejected an injunction to close down Genkai 3&4. In 2009, Genkai 3 became the first commercial reactor in Japan to use plutonium-uranium mixed oxide (mox) fuel, which uses plutonium and uranium extracted from reprocessing used reactor fuel — a key feature of Japan’s nuclear fuel recycling policy. After being shut down, like other nuclear reactors nationwide in the aftermath of the Fukushima crisis, Genkai 3&4 resumed operation in 2018. Kyushu Electric, meanwhile, has decided to decommission the Genkai plant’s ageing 1 and 2 reactors.