2011-06-17 11:00

A radioactive water treatment facility inside the south side of the fourth floor of Tokyo Electric Power Co.(TEPCO)'s Fukushima Daiichi nuclear power plant Unit 4 reactor in Fukushima prefecture, northern Japan is pictured in this handout photo taken June 9, 2011 and released by TEPCO June 11, 2011. [Photo/Agencies]

TOKYO - Japan's crisis-hit nuclear power plant could spill more radioactive water into the sea within a week unless engineers can fix a glitch in a new system to clean up pools of contaminated water, officials said.

Tokyo Electric Power Co , known as Tepco, has pumped massive amounts of water to cool three reactors at the Fukushima Daiichi plant, which had meltdowns after the 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 , US firm Kurion and other companies, has been test-running a system in which radioactive water is decontaminated and re-used to cool the reactors.

In a setback, it said water had leaked from a facility used to absorb cesium on Thursday, but it hoped to replace equipment and start the decontamination process by the end of Friday as planned.

"We are working on this with plans (to start the system) today," a Tepco official told reporters.

If the treatment system does not work, the complex could run out of space to store contaminated water as early as June 20, and it could then spill into the sea, Tepco has said.

The start of Japan's monthlong rainy season has also added to the risk of a buildup.

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.