The Nuclear Regulation Authority on Wednesday decided to propose to a government task force that the management of radiation doses on an individual basis is vital to working out measures to protect people seeking to return to their homes after the 2011 Fukushima Daiichi nuclear power plant disaster.
The proposal is expected to bring about a change in the government's policy of using "estimated" personal doses, calculated from air dose levels measured by radiation monitoring posts and other sources, when setting evacuation zones and other protective steps.
But as radiation exposure measured by individual dosimeters tends to be lower than estimated doses, the latest move could effectively mean a relaxation of the rules, making it easier for the government to achieve its long-term goal of reducing exposure doses to 1 millisievert per year in contaminated areas.
Estimated doses are calculated on the assumption that an individual remains eight hours outdoors and 16 hours indoors.
NRA Chairman Shunichi Tanaka said at a meeting of NRA commissioners that grasping individual doses is "essential" when evacuees return homes, because each person's lifestyle is different.
"Individual doses differ, and that could affect health," he said.
The proposal also called on the government to present a road map showing the timeline for measures it will implement to help people decide whether to return to their homes as well as to support those who decide to do so.
The measures include creating a team of counselors for each community that will help residents take radiation protection measures based on their dosimeter readings and respond to their concerns.
More than two years have passed since the Fukushima crisis was triggered by a huge earthquake and tsunami, but around 150,000 Fukushima Prefecture residents still live as evacuees.
In August, the government finished reclassifying areas where evacuation orders are in place to three categories based on radiation levels -- a zone where evacuation orders are ready to be lifted, a zone where habitation is restricted and a zone where residents will have difficulties in returning for a long time.
Decontamination efforts are being made but there has not been a case in which an evacuation order has been lifted.