Japan nuclear watchdog halts Tsuruga reactor safety assessment again

Nuclear regulators said Wednesday they will again halt a safety assessment of an offline central Japan reactor after its operator repeatedly submitted documents containing errors, further prolonging a process toward resumption that has already taken years.

Japan Atomic Power Co. has been seeking approval to reboot the No.2 unit at the Tsuruga plant in Fukui Prefecture under stricter regulations imposed following the 2011 Fukushima nuclear power plant disaster, but its application has been fraught with mistakes and data tampering.

The Nuclear Regulation Authority considered forcing the operator to withdraw its safety review application, but it ended up deciding on another suspension, citing how restarting the process all over the again would only burden the regulator.

While public concern over the safety of nuclear facilities lingers following the Fukushima disaster, triggered by a massive quake and tsunami, the government is pushing the use of nuclear power as part of efforts to secure a stable electricity supply amid the war in Ukraine.

Among the more than 30 existing nuclear reactors in Japan, 10 have resumed operations after clearing the post-Fukushima disaster safety hurdles, while 10 are still under examination by the nuclear watchdog, according to government data.

The Tsuruga nuclear power plant is a two-unit complex, with the No. 1 reactor set to be scrapped. Japan Atomic Power submitted the safety review application for the No. 2 unit in 2015.

In 2019, the nuclear regulators found over 1,000 inaccuracies in the documents submitted for measures against earthquakes and tsunamis, followed by revelations in February 2020 that the operator had rewritten data analyzing a drilling survey conducted on an area below the Tsuruga complex premises without approval.

After a two-year suspension of the safety review, assessments restarted but they have remained at a virtual standstill as the regulators discovered errors in the locations given for geological features over the past months.

In quake-prone Japan, building nuclear plants or other important facilities directly above active faults is prohibited.

Geological experts for the Nuclear Regulation Authority previously stated that a fault running underneath the No. 2 reactor was active, although Japan Atomic Power has rejected the claims.

© Kyodo News