At just 5 percent of full transmission, the Takahama Unit 4 reactor in the Fukui Prefecture in Japan automatically shut down Monday, just three days after its restart due to an undetermined glitch in the vicinity of a transformer, Japanese media reported.
Kansai Electric Power Company said it had stopped all restart activity in order to figure out what caused the reactor to shut a second after it had started generating power. With media monitoring the restart, the reactor shut down with control rods inserted into place to halt the reactor's neutron flux, reported The Japan Times.
The company said the reactor's return to commercial operations would likely be pushed back to April from a previous expectation of a late March return.
The restart had already been delayed by the Feb. 20 discovery of a coolant leak in the reactor building that was attributed to a loose bolt that was one of four holding a valve in place in a high-pressure pipeline. A thorough examination of similar valves in Unit 4 and Unit 3 was conducted before Unit 4's restart resumed on Friday.