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Thursday, 25th October 2012
In General Japan News,

NRA releases projections for any future radiation spills

Nuclear regulatory authorities (NRA) in Japan have recently released the first projections for the spread of radiation from nationwide reactors, in case a disaster such as the 2011 Fukushima Daiichi tragedy occurs again.

Radiation simulations were conducted on 16 atomic plants around Japan to give references for local governments to increase the size of evacuation areas from the present radius of ten kilometres, said the NRA.

In careful estimations supplied by NRA, if a large-scale accident occurs evacuation is recommended for 40 kilometres surrounding the Tokyo Electric Power Co.'s Kashiwazaki-Kariwa plant in Niigata Prefecture for at least one week.

Planning to advise that emergency zones should be set within a radius of approximately 30 km in its new nuclear disaster mitigation measure guidelines, it will have local governments considering extending this to a larger distance.

Assuming all seven nuclear reactors suffer meltdowns at the Kashiwazaki-Kariwa plant, the NRA found that doses of radiation could reach 100 millisieverts in the city of Uonuma in Niigata Prefecture, about 40.2 km away.

Areas slightly further out of a 30 km radius from Fukushima Prefecture's Tokyo Electric's Fukushima Daini, Chubu Electric Power Co.'s Hamaoka plant in Shizuoka Prefecture and Kansai Electric Power Co.'s Oi plant in Fukui Prefecture could suffer from 100 millisieverts radiation doses.

In the first seven days of exposure due to a radioactive emergency, the International Atomic Energy Agency calls for evacuations when effective doses exceed 100 millisieverts.

The NRA explained that simulations are based on simple criteria, such as weather patterns; however it did not include other factors, such as geological formations in potentially affected areas.

Commissioner of the regulatory body, Kunihiko Shimazaki stated that the results are "very important" in understanding how far contamination can travel, but he did acknowledge that simulations need to include additional factors, such as land features to get a clearer picture of the potential effects and plan for it accordingly.

In line with IAEA standards, the plans include concepts such as "precautionary action zones" and "urgent protective action planning zones", which will be finally decided upon by local governments.

Posted by Mark Smith