After the loss of all external power sources caused by the March 11 tsunami in Japan, an emergency cooling condenser at the Fukushima No. 1 Nuclear Power Plant appears to have only partially run, the plant’s operator said.
There are two systems comprising the “isolation condenser (IC),” which should cool down steam in a nuclear reactor in time of emergency, according to plant operator Tokyo Electric Power Co. (Tepco).
When employees examined the plant on Oct. 18, the levels of coolant in the two systems in the plant’s No. 1 reactor were at 65 percent and 85 percent. The coolant evaporates in the process of heat exchange.
Noting water has not gone to either of the systems since the disasters on March 11, Tepco officials said they suspect the IC in the No. 1 reactor functioned only at a limited level or over a short period.
As to the cause of the suspected malfunctioning, Tepco said hydrogen generated by damaged nuclear fuel may have gathered in the piping, causing the IC’s heat removal efficiency to decline. During the inspection on Oct. 18, workers found no damage to the IC in the No. 1 reactor.
A high-ranking official of Tepco said the IC would not have prevented the damage in the reactor even if it had functioned properly.
“Even if the IC had been working, it could have only delayed the damage to the reactor core a little bit. It wouldn’t have been a fundamental solution,” said Junichi Matsumoto, head of Tepco’s nuclear power division.
After the IC automatically activated in response to the earthquake, a worker manually stopped it and then restarted it.
The government’s accident investigation panel is investigating to see if the IC properly operated and if it functioned properly.