The system keeping spent fuel cool in the pool for reactor 3 at the Fukushima No. 1 power plant stopped Friday and was restarted three hours later, Tokyo Electric Power Co. said.
In the latest glitch at the crippled facility, an alarm sounded at 2:27 p.m. and technicians soon confirmed that the cooling system was not working, a Tepco spokesman said.
“We have no information at hand about the cause,” the spokesman said.
Although the breakdown was not thought to be immediately dangerous, it served as a reminder of the precarious state of the atomic plant more than two years after it was crippled by the giant tsunami of March 2011.
Last month, a power outage at the plant stopped cooling systems for four pools storing spent nuclear fuel after a rat interfered with the electrical flow.
As of 2 p.m. Friday, the temperature inside the reactor 3 pool was 15.1 degrees, indicating the spent fuel was stable and was not posing an immediate danger to the environment, Tepco said.