TOKYO: At least 45 tonnes of highly radioactive water has leaked from a purification facility at the Japan's Fukushima Daiichi nuclear power station and some of it may have reached the Pacific Ocean, the plant's operator said.
Nearly nine months after Fukushima Daiichi was ravaged by an earthquake and tsunami, the plant continues to pose a huge environmental threat.
Before the latest leak, it was estimated that the Fukushima accident had been responsible for the largest single release of radioactivity into the ocean, threatening wildlife and fisheries in the region.
Advertisement: Story continues below The new radioactive water leak questions what progress the plant's operator, Tokyo Electric Power Co (TEPCO), has made in bringing its reactors under control. The company had said it hoped to bring the plant to a stable state, known as a cold shutdown, by the end of the year.
The problems on Sunday came in two stages, a TEPCO statement said.
In the morning, utility workers discovered radioactive water flooding a catchment next to a purification device. This was switched off and the leak appeared to stop. But the company later found that leaked water was escaping through a crack in the catchment's concrete wall and reaching an external gutter.
It is estimated that about 220 tonnes of water may now have leaked from the facility, the Asahi Shimbun reported, quoting TEPCO officials.
The newspaper says the water may have contained up to one million times as much radioactive strontium as the maximum safe level set by the government, and about 300 times as much radioactive cesium. Both are readily absorbed by living tissue and can greatly increase the risk of developing cancer.
TEPCO said it was looking at ways to stop the water from leaking through the crack.
Since the disaster in March, workers have been struggling to cool the damaged plant's reactors by flooding them with water, which is contaminated with radioactivity in the process and becomes a problem of its own.
TEPCO installed a new circulatory cooling system in September that was meant to decontaminate and recycle the cooling water.
But the company acknowledges that some water has already leaked into the ocean and more remains in the flooded basements of the plant's reactor buildings.
The Institute for Radiological Protection and Nuclear Safety in France estimates that between March and mid-July, the amount of radioactive cesium 137 that had leaked into the Pacific from the Fukushima Daiichi plant amounted to 27.1 petabecquerels, the greatest amount known to have been released from a single episode. (A becquerel is a frequently used measure of radiation, and a petabecquerel is a million billion becquerels.)
Ocean currents rapidly dilute the leaking radioactive water, the institute said, but molluscs, deepwater fish and predators high in the marine food chain can be sensitive to radioactive cesium pollution.
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