Back-up cooling systems at Fukushima failed
http://www3.nhk.or.jp/daily/english/17_04.html
The operator of the Fukushima Daiichi nuclear power plant has admitted that the reactors’ back-up cooling systems failed to function after the March 11th earthquake and tsunami.
Tokyo Electric Power Company on Monday revealed the plant’s operation records for the period following the disaster on March 11th.
An emergency condenser system at the Number 1 reactor functioned for less than 10 minutes after the earthquake. The failure lasted for 3 hours.
The utility suspects that workers manually shut down the system as pressure inside the reactor became so low that they were afraid of damage.
Another type of back-up cooling system at the No. 1 and 2 reactors lost power when the tsunami engulfed batteries.
TEPCO is still analyzing the data to assess the failure’s impact on fuel rods.
Tuesday, May 17, 2011 07:31 +0900 (JST)
http://www3.nhk.or.jp/daily/english/17_22.html
Nuclear plant cooling system manually shut down
The operator of the Fukushima Daiichi nuclear power plant says workers may have manually shut down the No.1 reactor’s emergency cooling system in order to prevent damage to the reactor. It says pressure inside the reactor had dropped sharply after the earthquake struck the plant on March 11th.
Tokyo Electric Power Company on Monday disclosed records of its operations at the plant.
They show that the reactor automatically halted operations after the earthquake.
The emergency cooling system was automatically activated but stopped about 10 minutes later and remained off for about 3 hours until after the tsunami arrived.
TEPCO says plant workers may have manually shut down the cooling system because pressure inside the reactor had dropped sharply from 70 to 45 atmospheres.
The system is designed to cool the reactor even if all external sources of power are lost, but the move to shut it down temporarily means that it did not fully function.
TEPCO says the decision may have been made based on a manual to prevent damage to the reactor.
It says if the system had worked, it may have had more time until the meltdown, so it will investigate developments leading up to the decision to turn it off and whether the move was correct.
Tuesday, May 17, 2011 13:18 +0900 (JST)