The Nuclear Regulation Authority (NRA) has given the green light to Kansai Electric Power Co’s management plan to continue operating units 3&4 of its Ohi NPP in Fukui Prefecture for up to 40 years from the start of operations. The approval is based on a new system that will review plans every 10 years starting after 30 years of operation.
The system was introduced with a revision of the law in May 2023, With the approval, Ohi 3 can operate until December 2031 and Ohi 4 reactor until February 2033. Under the previous system, both reactors were allowed to operate for up to 40 years but only following inspections of the state of the equipment.
In May 2023, the Diet (parliament) passed the GX (green transformation) decarbonised power sources law. This effectively allows NPPs to operate for longer than 60 years by excluding shutdown periods, subject to NRA review.
After 30 years of operation, electric power companies are required to create a management plan detailing reactor deterioration for a maximum period of 10 years. NRA concluded that additional inspection items compiled by Kansai Electric on reactor degradation for Ohi 3&4 met its screening criteria.
“We will continue to actively incorporate the latest knowledge from Japan and abroad and reflect it in plant design and equipment maintenance, thereby striving to improve the safety and reliability of nuclear power plants,” Kansai said.
Plants that have been in operation for more than 30 years will not be allowed to operate without approval of a management plan after next June, when the new system comes into full effect.
Of the plants that have resumed operation, nine reactors, in addition to Ohi 3&4, will have been in operation for 30 years or more by June 2025. Kyushu Electric Power Co has applied for a management plan review for units 1&2 of its Sendai NPP in Kagoshima Prefecture. More applications are expected to follow.
Ohi 3 began operation 32 years ago, and Ohi 4 started 31 years ago. The reactors gained permission for operation extensions to 40 years under the old regulatory system in November 2021 and August 2022. However, they needed to be screened and approved again under the new system before the green transformation law is fully enforced.
