Human error suspected at Number 4

March 27, 2014

Error suspected in spent fuel removal trouble

http://www3.nhk.or.jp/nhkworld/english/news/20140328_02.html

The operator of the Fukushima Daiichi nuclear plant says human error was most likely the cause of a problem that halted spent fuel removal at one of the crippled reactors.

Tokyo Electric Power Company has been transferring hundreds of spent and unused fuel assemblies from a pool in the damaged no.4 reactor building to a safer facility in the site.

But on Wednesday, a crane used to hoist a cask containing fuel assemblies from the pool suddenly stopped, halting work.

TEPCO officials say a worker mistakenly tried to operate the crane with an auxiliary brake on. Noticing the error, he released the brake and retried, but the crane failed to operate once the warning lamp had gone on.

The officials say the worker's error led to excess current to the crane's motor, which automatically locked operation. The problem didn't damage the crane or its motor.

They say they will soon resume fuel transfer operations, taking preventive measures including rechecking the work process.

In November last year, TEPCO started operations to remove more than 1,500 spent and unused fuel assemblies from the pool in the crippled No.4 reactor building. As of Tuesday 550 assemblies had been removed.

Mar. 27, 2014 - Updated 17:04 UTC