The government is tightening radiation exposure levels currently used to designate an evacuation zone around the Fukushima No. 1 nuclear plant, as the crisis triggered by last month's massive earthquake and tsunami continues.
"The current standards represent safety in the event of absorbing a huge amount of radiation in a short period," Chief Cabinet Secretary Yukio Edano said at a news conference, noting some changes may be necessary as residents near the plant are at risk of absorbing radiation over an extended period.
The government's Nuclear Safety Commission is proposing the government tighten the limit to 20 millisieverts from the current 50 millisieverts.
Currently the government says outside radiation levels over 50 millisieverts requires evacuation, and advises residents to remain indoors when levels exceed 10 millisieverts.
Based on these figures, the government has ordered residents within a 20-km radius of the nuclear plant to evacuate and those in the 20- to 30-km zone to stay indoors.
Shrouds maybe later
A plan to cover damaged reactor buildings at the Fukushima No. 1 nuclear plant with special sheets won't be providing a quick remedy because the shrouds can't be installed until September at the earliest due to the high levels of radiation hampering work at the site, government sources said.
The government had asked Tokyo Electric Power Co. to study the installment of radiation-shielding sheets, and a major construction firm commissioned to examine the idea said the construction won't start until June, the sources said.