Photo/Illutration The No. 2 reactor at Japan Atomic Power Co.’s Tsuruga Nuclear Power Plant in Tsuruga, Fukui Prefecture (Asahi Shimbun file photo)

The Nuclear Regulation Authority is suspending the screening process for restarting a nuclear reactor in Fukui Prefecture.

The decision came on Aug. 18, after the regulator discovered that records used in assessing the reactor’s safety were altered without permission, making the data unreliable.

The move will further prolong the already lengthy evaluation process.

It has stretched on for five and a half years because of a disagreement over whether a fault line under the No. 2 reactor at the Tsuruga Nuclear Power Plant is currently active.

An expert panel under the NRA, a government watchdog that was established after the 2011 Fukushima nuclear disaster, had raised the prospect that the fault could be active.

But Japan Atomic Power Co. (JAPC), operator of the plant, disagreed with that view, and has been trying to prove that the fault is not active since screening started in November 2015.

In February 2020, the NRA discovered that a document containing safety research into the status of the fault was rewritten without permission.

The document contained geological layer observations recorded when drilling was carried out to determine whether the fault is active.

JAPC had used the document to back up its claim about the fault.

The power company admitted that its officials made 80 modifications to the document at their own discretion to reflect the latest information found in a separate geological survey. Some changes were made to rule out the possibility that the fault had moved in the past.

The officials were unaware they should not have modified the data, according to JAPC.

The regulatory authority will not resume the safety screening process until JAPC properly creates a reliable document for the screening. The length of the suspension period will depend on how the power company responds, but it is unlikely to last for multiple years, according to an NRA official.

JAPC owns four nuclear reactors, but two of them have been scrapped.

In its ruling in March, the Mito District Court ordered JAPC to suspend the Tokai No. 2 nuclear power plant in Tokai, Ibaraki Prefecture, which had passed a safety screening for a restart. The court ruling said JAPC failed to compile realistic evacuation plans for residents living near the single-reactor plant in the event of an accident.

(This article was written by Yu Fujinami, Tsuyoshi Kawamura and Satoshi Shinden.)

Related News