From now on ... 20 millisieverts is OK

March 12, 2013

New N-safety rules planned / Guidelines aimed at easing fears of return to homes in Fukushima

http://www.yomiuri.co.jp/dy/national/T130311004443.htm

The Yomiuri Shimbun

The government plans to draft safety guidelines based on annual radiation exposure, to facilitate the return of residents in Fukushima Prefecture who evacuated following the outbreak of the crisis at the Fukushima No. 1 nuclear power plant, according to government sources.

The new guidelines will likely allow the evacuees to return as early as spring next year to areas designated as zones being prepared for residents' return, where the annual radiation dose is 20 millisieverts or less.

The government will draw up the guidelines by the end of this year, after the Nuclear Regulation Authority sketches them out in consultation with experts in Japan and elsewhere.

The so-called one-millisievert framework created under the Democratic Party of Japan-led government has hindered residents' return. After the outbreak of the nuclear crisis in 2011, the DPJ-led government set a long-term goal of lowering radiation exposure to no more than one millisievert annually.

This number has been considered a de facto safety standard, obstructing local residents' return to their hometowns.

Residents will be able to return once the evacuation directive is lifted, but many are afraid to do so, a government official said.

"Evacuees feel they can't return home because they think it isn't safe unless [the radiation dose] is one millisievert or less," the official said.

The current administration plans to maintain one millisievert as a long-term target, but the new guideline is expected to present measures based on different radiation levels by which people can live without worry--such as annual accumulated doses of five to 10 millisieverts.

The International Commission on Radiological Protection said the effects of radiation exposure on the human body are not clear up to an annual dose of 100 millisieverts. People visiting a hospital can receive a dose of seven millisieverts from one examination involving radiation.

The guideline may help the government review the decontamination target, observers said. Decontamination work requires an immense amount of labor and funding.

"[The former government] set a target of one millisievert in the chaotic aftermath of the disaster, and it's difficult to achieve," a government official said.

Fukushima Gov. Yuhei Sato also asked the government in February to clarify the safety standard. There is a major difference between 20 millisieverts, the annual level below which people can return home, and the one-millisievert long-term target for decontamination, which is a major impediment to the rehabilitation of the disaster-stricken areas, he said.

According to a calculation by the National Institute of Advanced Industrial Science and Technology, the cost of decontamination and other related work in 11 municipalities designated as evacuation zones will amount to at least 1.29 trillion yen.

"If the cost of radiation control is added, it will likely be more than 2 trillion yen," a researcher with the institute said.