Power was mostly restored at Japan’s Fukushima Dai-Ichi nuclear station after an outage caused a stoppage of water pumps used to cool spent uranium fuel at the tsunami-damaged plant.
No spikes in radiation levels were recorded near the plant during the failure that started shortly before 7 p.m. yesterday, the government said. The outage did not affect cooling systems for the plant’s reactors, the Nuclear Regulation Authority said in an e-mailed statement.
There was “absolutely no change” reported in radiation, Yoshihide Suga, Japan’s chief cabinet secretary, said at a media briefing today. Without power to pump cooling water through the pools, the rods could have heated up over days and released radiation.
Three reactors melted down at the Dai-Ichi plant after the earthquake and tsunami on March 11 two years ago, making it the world’s worst nuclear accident after Chernobyl. About 160,000 people were forced to evacuate and a 20-kilometer no-go zone was set up because of radiation fallout.
Pumps at four cooling pools lost power, with electricity for the one in reactor building No. 1 reconnected to the main power supply this afternoon, Masayuki Ono, a general manager at plant operator Tokyo Electric Power Co., said at a press conference this evening. Pumps in the No. 4 building were now connected to a diesel generator and will be linked to the main system at 8 p.m., Ono said. The No. 4 pool holds more than 1,500 spent fuel rods, according to the company.
“We are attacking this with all necessary speed,” Ono said. The loss of electricity may have been caused by a power distribution box and is being investigated, he said at an earlier briefing.
The pool in the No. 3 building is also due to resume cooling operations by 8 p.m. A separate shared cooling pool is scheduled to resume by 8 a.m. tomorrow, Ono said. Power was restored earlier today at a purification system in the plant for removing radiated particles from water, he said.
Spent fuel pools are typically 40 feet deep and built in reactor buildings. They’re made of reinforced concrete several feet thick and steel sheeting to contain radiation and hold water to cool rods after they have been used in a reactor, according to the U.S. Nuclear Regulatory Commission.
Tokyo Electric and Japan’s government announced in December 2011 that the Fukushima reactors reached a state known as cold shutdown nine months after the March 11 earthquake and ensuing tsunami caused the biggest release of radiation since the Chernobyl accident in 1986.
Japan’s previous government approved phasing out nuclear power by the end of the 2030s, a policy favored by the largest percentage of citizens in a government poll in August.
Japanese Prime Minister Shinzo Abe, whose Liberal Democratic Party won a landslide majority in December, has said that policy needs to be reconsidered to provide the energy needed to help revive the world’s third-biggest economy.