Second Japanese BWR set to restart in December

Tuesday, 15 October 2024

Revised regulations were announced by Japan's Nuclear Regulation Authority (NRA) in July 2013, which must be met before reactors can receive permission to restart. These set out requirements for plants to be able to respond to a variety of natural phenomena as well as establish new measures to mitigate the effects of severe accidents, such as reactor core damage caused by beyond design basis events. Chugoku applied to the NRA in December 2013 for inspections to verify whether measures taken at Shimane unit 2 - which has been offline since 27 January 2012 - meet the new safety standards.

Chugoku has constructed a 15-metre-high sea wall to protect the plant from tsunamis and made preparations for a potential eruption of the Mount Sanbe volcano. It originally aimed to complete seismic reinforcement and other works for Shimane 2 by the end of February 2023. 

In June 2021, the NRA approved a draft report finding that Shimane 2 meets the revised regulatory standards. The assessment of the unit was officially adopted in September 2021 after a public comment period and other procedures, clearing the way for it to resume operation, pending local consent. Shimane 2 became the 17th Japanese reactor to pass the regulator's safety screenings and the fifth BWR - the same type as those at the Fukushima Daiichi plant - to receive regulatory approval to restart.

Following approvals by the cities of Matsue, Izumo, Yasugi and Unnan, in June 2022 the governor of Shimane prefecture approved the restart of Shimane 2. His approval marked the completion of the process to gain the consent of local communities for the 789 MWe BWR to resume operation.

Shimane 2 had been scheduled to restart in August, but Chugoku pushed back the restart due to required safety upgrade work. 

The utility has now released a revised schedule for the restart of the unit. It plans to begin loading fuel into the reactor's core on 28 October, with the unit expected to restart in early December. Power generation is scheduled to begin in late December, with the reactor resuming commercial operation in January 2025.

"We will continue to take all possible measures to ensure the operator's pre-operational inspections proceed steadily with safety as our first priority as well as to respond appropriately to the pre-operational confirmation conducted by the NRA, and we will prepare each and every step toward the restart," Chugoku said.

So far, eleven reactors have resumed operation in Japan, all of which have been pressurised water reactors.

Shimane unit 1 - a 460 MWe BWR that started commercial operation in March 1974 - is currently being decommissioned. In August 2018, Chugoku initiated the regulatory process for starting up Shimane 3, a new 1373 MWe advanced boiling water reactor nearing completion.