What's going on at reactor No.4?

July 1, 2012

Cooling system for Fukushima Daiichi No. 4 reactor fuel pool shuts down

http://mainichi.jp/english/english/newsselect/news/20120701p2g00m0dm011000c.html

TOKYO (Kyodo) -- The cooling system for the spent fuel pool at the crippled Fukushima Daiichi power plant's No. 4 reactor automatically shut down Saturday, Tokyo Electric Power Co. said.

The utility known as TEPCO has been unable to activate a backup cooling system for the pool, officials of the plant operator said later in the day, adding it is unlikely the temperature will rise rapidly.

TEPCO believes a part of power unit of the system's heat exchanger is causing the problem and the company will try to get the system running again on Sunday.

The water temperature of the pool was 31 C when the cooling system shut down around 6.25 a.m., and was rising 0.26 C per hour by late Saturday afternoon, according to the utility.

If TEPCO continues to be unable to cool the pool, the temperature could reach 65 C, the upper limit designated in the safety regulations, by Tuesday morning. No leakage of water with radioactive materials has been found, TEPCO said.

The cooling system at the No. 4 reactor was previously suspended on June 4.

June 30, 2012

Cooling system suspended at Fukushima nuke plant No. 4 reactor

http://mainichi.jp/english/english/newsselect/news/20120630p2g00m0dm049000c.html

TOKYO (Kyodo) -- The cooling system for a spent fuel pool at the crippled Fukushima Daiichi power plant's No. 4 reactor automatically suspended operation Saturday morning after an alarm issued a warning at around 6:25 a.m., Tokyo Electric Power Co. said.

The water temperature of the pool was 31 C at the time of the suspension, and leakage of water with radioactive materials has not been confirmed, TEPCO said, adding it is unlikely the temperature will rise rapidly.

The cooling system at the No. 4 reactor was previously suspended on June 4.