FUKUI – Commercial operation of the troubled reactor 4 at the Takahama facility in Fukui Prefecture will likely be pushed back to April after the Nuclear Regulation Authority said it will be difficult to proceed until preventive steps are approved.
Kansai Electric Power Co. had initially planned to start commercial operation of the reactor in late March.
The change in schedule became necessary after the reactor shut down automatically Monday, only three days after coming back online under safety regulations strengthened following the 2011 Fukushima meltdowns.
Kansai Electric said there was no leak of radioactive substances in the incident. But the shutdown followed a leak of radioactive coolant water at the reactor just days before its restart.
The utility said Tuesday a strong electrical current beyond a preset level may have been detected by a monitoring device around a transformer of the reactor, causing an alarm to go off upon the start of power generation and power transmission.
Also Tuesday, the utility began the process of bringing the unit to a state of cold shutdown by lowering the temperature of coolant water.
The NRA will eventually have to examine Kansai Electric’s analysis of the cause of the emergency halt and measures to prevent a similar incident.
Even if it gets the go-ahead for another restart, the No. 4 reactor will need to go through a final inspection by the NRA again before reactivation and subsequent commercial operation.
The latest incident was the second halt of the reactor in 10 days, following the radioactive coolant water leak on Feb. 20 in a building attached to the reactor. Kansai Electric had rebooted it, deeming it had taken sufficient steps to prevent a similar leak.
The rash of incidents come as the government aims to bring more reactors back online after the disaster at the Fukushima No. 1 nuclear power plant led to a nationwide shutdown of nuclear plants, as it is seeking to generate at least 20 percent of Japan’s electricity through nuclear power by 2030.
“It’s very regrettable,” industry minister Motoo Hayashi said of the latest incident. “I hope Kansai Electric will do its utmost to find the cause of the incident and work extra carefully,” putting safety ahead of the need to restart the reactor quickly.