Tokyo Electric Power Co. said Sunday it temporarily halted the system to decontaminate radioactive water at the crippled Fukushima Daiichi nuclear power plant in Fukushima Prefecture after discovering that about 50 liters of contaminated water and chemicals used in the system were leaking from a pipe after a part broke.
The utility has been using the decontaminated water to cool the Nos. 1-3 reactors at the plant, and even during the temporary suspension to fix the part, it was able to continue the cooling function using water that had already been decontaminated, it said.
"The concentration of radioactive substances in the leaked contaminated water was not at levels that would cause problems involving workers' exposure to radiation," a Tepco official said.
The leak occurred in a section of a device developed by France's Areva SA where the chemicals, which are used to condense and precipitate radioactive materials in the contaminated water, are injected from a hose into a pipe through which the polluted water passes, according to Tepco.
The plastic part broke, causing the chemicals and contaminated water to leak, the company said, adding that workers replaced the part with a steel one and resumed operation of the water treatment system.
The chemicals are not toxic, Tepco said.
Smooth operation of the treatment system, which is designed to remove highly radioactive materials from the massive quantities of contaminated water accumulating at the power station, is essential for containing the nuclear crisis, as Tepco recycles the water to cool the plant's damaged reactors.
The contaminated water accumulating at reactor facilities, including coolant liquid leaking from damaged reactors, has been diverted elsewhere at the plant to prevent it from overflowing from the facilities, but the storage locations are nearing full capacity.