Friday, April 29, 2011

Japan plant worker exposed to radiation

Japan plant worker exposed to radiation*


Tokyo - A female employee at the damaged Fukushima nuclear power plant in north-eastern Japan is reported to have been overexposed to radiation while authorities have detected high levels of radiation in fish and spinach produced near the plant, a news report said on Thursday.

The radiation exposure of the woman measured at the end of March was 17.55 millisieverts, exceeding the legal limit of 5 millisieverts over any three-month period for women, plant operator Tokyo Electric Power Company (Tepco) said.

Closer examination has showed that the woman who refuelled fire trucks suffered 13.6 millisieverts of internal radiation exposure.

She was working in an on-site building contaminated by high-level radioactive materials following a hydrogen blast on March 12. The worker, who was not wearing a protective mask, may have inhaled some of the airborne radioactive material, NHK said.

Tepco has apologised for its lack of precautions against internal radiation exposure, NHK said. Two more female employees may also have been exposed to radiation in excess of the limit.

Hidehiko Nishiyama, a spokesperson for the government's Nuclear and Industrial Safety Agency, told a news conference that the situation was "extremely deplorable".

Fish, spinach contaminated

Nishiyama urged Tepco to find out the cause and draft prevention measures.

On Tuesday, 2 600 to 3 200 becquerels per kilogram of radioactive caesium was found in two samples of sand lance caught off Iwaki city, south of the Fukushima Daiichi Nuclear Power Station. That is five to six times above the legal limit, public broadcaster NHK reported.

Local government officials on Sunday also detected 960 becquerels of caesium per kilogram in spinach harvested in Otama village in Fukushima prefecture.

The Fukushima nuclear plant was severely damaged by the March 11 earthquake and ensuing tsunami and has been leaking radioactive material ever since.

The government has set the safety standard for leafy vegetables at 500 becquerels per kilogram. Shipments of several kinds of vegetables and fish from near the plant have been already banned, NHK said.

Workers at the plant were to start in June to decontaminate radioactive water, which has prevented workers from accessing the site to restore key cooling functions, the government said.

Water to be recycled

Tepco said 87 500 tons of contaminated water was found in the basements of the turbine buildings of reactors 1 to 4 and in trenches nearby.

In addition, about 500 tons of contaminated water per day is leaking from the reactors due to efforts to cool them by injecting water.

Toshiba Corporation and Hitachi-GE Nuclear Energy Ltd, a joint venture between Hitachi Ltd and US partner General Electric Company, is to install a water recycling system in May, Jiji Press said.

The system is to process 1 200 tons of water per day, treating about 200 000 tons by the end of the year.

At first, oil will be eliminated from radioactive water, then radioactive caesium will be removed using zeolite adsorbents, a sort of chemical sponge, Jiji reported.

A system developed by French firm Areva SA will get rid of other radioactive substances.

As a result, the concentration of caesium and iodine is expected to be reduced to one-10 000th of its current concentration.

Radioactive substances eliminated from the water will be stored at the plant for the time being.


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