Malfunction closes Tepco nuke reactor

Kyodo

Tokyo Electric Power Co. said it shut down one of its nuclear reactors in Fukushima Prefecture on Wednesday evening following a malfunction.

Tepco’s No. 2 nuclear reactor at its Fukushima No. 1 nuclear power plant was shut down due to a problem with its reactor recirculation system pumps, it said.

Tepco officials said that no external radiation leak was detected at the reactor, which is about 250 km north of Tokyo.

An alarm indicated trouble in one pump system around 8:35 a.m. The pump was automatically switched off and the reactor’s output fell to 540 megawatts from the normal level of 784 megawatts, they said.

As engineers manually reduced the output to around 200 MW, another alarm indicated trouble in another pump system. Tepco then decided to shut down the reactor, they said.

The trouble was detected in inverters that had been replaced during regular checkups earlier this year, they said.