Tokyo Electric Power Company, operator of the tsunami-crippled Fukushima nuclear power plant, said the facility's system for treating irradiated water suffered a new technical defect and had to be temporarily halted.
The failure occurred at one of the three lines of the so-called Advanced Liquid Processing System, which has been partially shut down on several occasions in recent months due to various problems, including radiation-induced filter gasket corrosion.
TEPCO technicians temporarily suspended the line on Friday before reactivating it later after replacing some filters, Japanese state-run broadcaster NHK reported Saturday.
ALPS, which is not yet fully operating, removes 62 types of radioactive material - except tritium - from the water used to cool the reactors, which were crippled in the March 2011 earthquake and subsequent tsunami, the worst nuclear disaster since the 1986 meltdown of the Chernobyl plant in Ukraine.
TEPCO aims to use this system to process much of the toxic water that is being stored at more than a thousand tanks at the Fukushima complex and it has set a March 2015 deadline for completing the work.
To accelerate this process, TEPCO also plans to bring online two new similar water-treatment facilities, including one with greater capacity than ALPS.
Some 360,000 tons of highly radioactive water in need of processing are being stored at Fukushima, located in the eastern Japanese town of Okuma.
Once ALPS is operating fully, it will be able to treat some 750 tons of irradiated water per day, according to TEPCO.
The accumulation of toxic water at Fukushima is one of the main challenges TEPCO faces in dismantling the crippled reactors, an operation expected to take three or four decades.
More than 3 1/2 years after the nuclear disaster, 50,000 people who lived near the Fukushima plant still cannot return to their homes due to high levels of radiation, which also has affected local farming, cattle-raising and fishing. EFE