TEPCO starts system to cool spent fuel pool at Fukushima plant

TOKYO (Kyodo) - The operator of the crippled Fukushima Daiichi nuclear power plant said Tuesday that it has started to fully operate a water circulation system to stably cool one of the pools storing spent nuclear fuel at the plant, marking progress in its efforts to bring the nuclear crisis under control.
Tokyo Electric Power Co. said, meanwhile, it had discovered that oil temporarily leaked into the sea near the plant located on the Pacific coast, while an oxygen cylinder ruptured during work to remove rubble earlier in the day.
The utility known as TEPCO is trying to contain the world's worst nuclear crisis since the 1986 Chernobyl disaster, in line with a road map that aims to stabilize sometime between October and January the plant's reactors and spent fuel pools, which lost their key cooling functions in the wake of the massive March 11 earthquake and tsunami.
The new water circulation cooling system was established for the spent fuel pool in the No. 2 reactor building. The system is also expected to help lower the extremely high humidity detected inside the building by reducing steam coming out from the hot water in the pool and to improve the working environment inside the building.
TEPCO spokesman Junichi Matsumoto said that the temperature of the pool's water is expected to fall to around 40 C from about 70-80 C by operating the system for about a month.
Similar systems are to be created for the spent fuel pools of the Nos. 1 and 3 units in June, as well as for the No. 4 unit in around July.
But on the same day, TEPCO found that oil had temporarily leaked into the sea near the plant from an oil pipe that may have been damaged in the March disaster. It said the leak has stopped and hastily set up oil fences to prevent the liquid from spreading into the Pacific Ocean.
Goshi Hosono, a senior government official tasked with handling the nuclear crisis, said in a press conference jointly held with TEPCO's Matsumoto and others in the afternoon that the amount of oil involved was ''extremely small.''
TEPCO workers detected the oil slick, which extended for 200 to 300 meters inside breakwaters at one point, at 8 a.m. when patrolling the plant.
Tokyo Electric suspects the oil leaked from a pipe believed to be connected to two heavy oil tanks located near the water intake for the Nos. 5 and 6 reactors. Recent typhoon-affected rainy weather may also have led to the leak, it said.
When the March 11 disaster struck the plant, a tanker was supplying oil to the tanks, each with a capacity of 960 kiloliters. One of them was moved from its original location because of the tsunami.
Aside from the oil spill, the sea close to the plant was earlier contaminated with highly radioactive water that leaked from the plant.
To reduce contamination of seawater enclosed inside the harbor, TEPCO said it will start test-operating from Wednesday a system to pump out the water and extract radioactive materials from it by using a mineral called zeolite.
In another incident, an explosion was heard at 2:30 p.m. near the No. 4 reactor building after remote-controlled heavy machinery damaged an oxygen cylinder while rubble was being removed. No one was injured and the radiation level in the area remained stable, TEPCO added.
Meanwhile, it was also revealed Tuesday that the head of a government task force on the Fukushima disaster has been absent since May 19 because of illness.
The task force head, senior vice industry minister Motohisa Ikeda, has been hospitalized, Economy, Trade and Industry Minister Banri Kaieda told a parliamentary committee.
A senior bureaucrat of the Nuclear and Industrial Safety Agency has been serving as acting chief, but the government had not announced the fact.