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August 31, 2012

Water levels at 3 damaged reactors fall twice

http://www3.nhk.or.jp/daily/english/20120831_15.html

Coolant water levels at 3 damaged reactors at the Fukushima Daiichi nuclear plant briefly fell below the necessary level twice on Thursday.

Tokyo Electric Power Company says the incidents do not pose an immediate threat to the safety of the reactors, but it will quickly take steps to identify and deal with the problem.

Workers found that the water levels of the first 3 reactors were about 10 percent below the necessary level on Thursday afternoon. The levels recovered later, after workers opened valves to add more water.

TEPCO says it noticed the reactors were not getting enough water again at about 8:00 PM on Thursday.
The necessary level of water was restored at about 10:30 PM.

TEPCO is investigating the incident. It suspects that something may be wrong with 2 pumps on higher ground that sent decontaminated water back into the reactors.
It is now using spare pumps.

The water levels of the 3 damaged reactors simultaneously fell below the necessary level for the first time since they were declared to be in a stable condition last December.

The reactors suffered meltdowns following the March 11th quake and tsunami last year.

TEPCO also says the spent fuel pool and the building of the No. 4 reactor are strong enough to resist a quake of 6 plus on the Japanese seismic scale.

The No.4 reactor was idle at the time of last year's disaster, but the building was damaged in a hydrogen explosion. Its pool is full of fuel rods, and the risk of further quake damage is a major concern.

TEPCO is trying to improve the quake-resistance of the facilities. The utility is also preparing to remove the fuel rods from the pool, with the goal of starting the operation in December next year.