Japanese nuclear expert calls for wider evacuation as Fukushima radiation spreads

Mamoru Fujiwara, assistant professor of nuclear physics at Osaka University, said the residents from these locations “need to be relocated permanently.”

Japan Finds Radiation Spread Over a Wide Area, WSJ, By MITSURU OBE, 31 Aug 11, TOKYO—The first comprehensive soil survey from areas around the Fukushima Daiichi nuclear plant showed extensive ground contamination and another report warned of the continued threat to Japan’s food chain, underscoring the major challenges the country still faces in its radioactive cleanup efforts….

Nearly six months after the accident, the education ministry released Tuesday the first comprehensive survey of soil contamination within a 62-mile radius, showing that more than 30 locations spread over a wide area have been contaminated with long-lasting radioactive cesium.

Government officials said the report did not materially alter their prior understanding of the spread and extent of contamination, previously estimated through aerial surveys and above-ground radiation monitoring. They said that the highest-contaminated communities had already been evacuated, and the new data did not justify any change in the evacuation policy.

But the extent of reported contamination does raise new questions about how quickly the communities can be cleaned up, and the dangers of radioactive materials spreading to a wider area through wind or rain.

The survey of 2,200 locations—conduced by 400 researchers in June and July—found that 33 of those locations had cesium-137 in excess of 1.48 million becquerels per square meter, the level set by the Soviet Union for forced resettlement after the 1986 Chernobyl disaster, Japanese authorities said.

Another 132 locations had a combined amount of cesium-137/134 of more than 555,000 becquerels per square meter, the level at which the Soviet authorities called for voluntary evacuation and imposed a ban on farming.

Mamoru Fujiwara, assistant professor of nuclear physics at Osaka University, said the residents from these locations “need to be relocated permanently.” He said the data showed the government should be more aggressive with its evacuation policies. “The government, Tepco and the prefecture must all take steps urgently to allow these people to move permanently, rather than keeping them in temporary evacuation arrangements,” he added.

Cesium-137 has a half-life of 30 years, meaning that its radioactive emissions will decline only by half after 30 years and will affect the environment over several generations. Cesium-134 has a half-life of two years.

Last week, the authorities said they expected the levels of radiation to decrease by half in areas around the plant in two years, through natural decay and cleanup efforts. But the latest data show how difficult that could be.

“It is possible that decontamination work will produce little results, as more cesium is expected to move in from higher grounds and forests, carried by winds and rains,” an education ministry official said in an interview. “Unlike those contaminated by the Chernobyl disaster, which are mostly flat and dry land, Fukushima is a mountainous region covered by forests and crisscrossed by streams,” added the official, who asked not to be identified….. http://online.wsj.com/article/SB10001424053111904332804576540131142824362.html

September 1, 2011 - Posted by Christina Macpherson | Uncategorized