High levels of strontium detected at damaged Japan nuclear plant
Jun 1, 2011, 6:59 GMT
Tokyo - High levels of a radioactive substance that collects in bones were found in soil samples from a damaged Japanese nuclear power plant, its operator said Wednesday.
Tokyo Electric Power Co (TEPCO) detected up to 480 becquerels of strontium-90 per kilogram of soil taken at three locations about 500 metres from the Fukushima Daiichi plant, public broadcaster NHK said.
The measurement was about 100 times higher than the maximum reading recorded in Fukushima prefecture in atmospheric nuclear tests conducted by foreign countries during the Cold War, NHK said.
The plant was hit by the March 11 earthquake and tsunami and has leaked radioactive substances into the environment ever since.
Once humans inhale strontium, it tends to accumulate in bones and can cause cancer. It has a half-life of 29.1 years.
TEPCO also reported detecting 2,800 becquerels of strontium-89 per kilogram of soil at the same location, NHK said. Strontium-89 has a half-life of 50.5 days.
In March, both strontium-90 and -89 were also found in soil and plants in Namie town and Iitate village, more than 30 kilometres from the plant.
The government's Nuclear and Industrial Safety Agency urged TEPCO to draw up plans to decontaminate the radiation-contaminated water inundating reactor buildings.
Recent rainfalls helped raise the level of the water by 6.2 centimetres in an underground tunnel extending from the building of reactor 2 during the 24 hours through Wednesday morning, NHK said.
The agency also told the operator to secure new storage sites where they can transfer the contaminated water quickly. With the wet season approaching, there are growing fears that rain will cause the water to flow out to the sea.
The operator said that since a water circulation system started to operate in reactor 2 on Tuesday, water temperature in the spent fuel pool has been falling gradually.
The temperature of water in the pool of reactor 2, which stood at 67 degrees Celsius late Tuesday afternoon, dropped to 64 degrees early Wednesday morning, Jiji press reported citing TEPCO.
The working environment has been 'extremely severe' inside the building of reactor 2, with humidity reaching 99.9 per cent due to evaporated water from the spent fuel pool, Jiji said.
TEPCO hopes the new cooling system would help lower the temperature of the water in the pool to around 40 degrees in one month, Jiji said.