Monju’s restart hit by faulty gas detector

Kyodo News

A gas leak detector marred the restart of the Monju fast-breeder reactor by developing problems on Friday, the government’s Nuclear and Industrial Safety Agency said.

An alarm fitted to one of three instruments that detect gas leaks started going off intermittently Friday morning, a day after Monju was revived following a shutdown of 14 years and five months, they said. No problems were reported and the reactor remains in operation, they said.

The same alarm went off on Thursday night, but technicians restarted the monitoring device after determining it was a false alarm. However, after the problem reoccurred Friday morning, they have concluded the equipment has developed problems.

Since two similar instruments are continuing to work normally, there are no concerns about the reactor’s safety-monitoring system.

The state-affiliated Japan Atomic Energy Agency said it would announce any problems, major or minor, when restarting the 280,000-kilowatt prototype fast-breeder reactor in Tsuruga, Fukui Prefecture, on Thursday morning. But it failed to mention the faulty alarm at a press conference at 10 a.m., delaying the finding until shortly after noon.

The reactor is expected to reach criticality, the point when a nuclear chain reaction becomes self-sustaining, on Saturday. The operators will then begin gradually raising its output, with an eye to reaching full capacity in spring 2013.