TOKYO The operator of Japan's crisis-hit nuclear power plant said it started an operation to clean up radioactive water later on Friday, after several glitches that delayed the plan.
Large and growing pools of radioactive water were in danger of spilling into the sea within a week unless the plan got under way, officials had said earlier this week.
Tokyo Electric Power Co, known as Tepco, has pumped massive amounts of water to cool three reactors at the Fukushima Daiichi plant that went into meltdown after a March 11 earthquake and tsunami disabled cooling systems.
But managing the radioactive water has become a major headache as the plant runs out of places to keep it. Around 110,000 tonnes of highly radioactive water -- enough to fill 40 Olympic-size swimming pools -- is stored at the plant.
Tepco, with help from French nuclear group Areva, U.S. firm Kurion and other companies, has been test-running a system in which radioactive water is decontaminated and re-used to cool the reactors.
But in a setback that delayed the plan by about a week it said water had leaked from a facility used to absorb caesium on Thursday.
Tepco official Junichi Matsumoto told reporters that the operator was aiming to use some of the cleaned water to cool the reactors within the next few days, which would not require the pumping in of fresh water.
DUMPED IN OCEAN
In early April, the utility dumped about 10,000 tonnes of water with low-level radioactivity into the ocean, prompting criticism from neighbours China and South Korea.
Even if the water treatment is successful, Tepco would next face the problem of dealing with highly radioactive sludge that will be left over from the decontamination process. It is unclear where the sludge will be stored in the long-term.
Despite the mounting challenges, Tepco aims to complete initial steps to limit the release of further radiation from the plant 240 km (150 miles) northeast of Tokyo and to shut down its three unstable reactors by January 2012.
Tepco announced on Friday, as expected, that it had not made significant changes to its timeline.
The operator said that storing high radiation sludge likely to result from the treatment of contaminated water and improving the conditions for their workers during the approaching summer were extra areas it was looking into.
Measures for the workers include access to more doctors and body counters that measure exposure to radiation and new resting areas away from the summer heat, Tepco said.
The ultimate goal is to bring the reactors to a state of "cold shutdown," where the uranium at the core is no longer capable of boiling off the water used as a coolant.
That would allow officials to move on to cleaning up the site and eventually removing the fuel, a process that could take more than a decade.
(Additional reporting by Shinichi Saoshiro; Editing by Alex Richardson)