Japan's Nuclear Regulation Authority decided Wednesday to revise its nuclear disaster response guidelines, mainly to clarify the conditions for lifting a shelter-in-place order.

In response to a report proposing a review of how to implement shelter-in-place orders that was compiled by an NRA expert team, the nuclear safety watchdog will also add a section on cases in which going outside should be permitted while such an order is in place.

The NRA's Secretariat will draw up a draft to revise the guidelines, which are expected to be officially adopted around autumn.

The current guidelines call for residents within 5 to 30 kilometers of a nuclear power plant to stay indoors if a release of radioactive materials is expected to occur in a serious accident.

But the shelter-in-place period and the timing of its lifting are not specified. The NRA set up the expert team in April last year to discuss the matter. The team compiled the report last week.

The report said that three days from the start of a shelter-in-place period can be considered "a timely point to judge whether to continue the order."

Based on feedback from local governments, the report revised the initial three-day guideline for the evacuation period, saying "whether to continue sheltering in place will be judged daily after the third day."

Local governments had raised concerns about a draft report released in February, since it "could lead to the misunderstanding that sheltering in place would end after three days."

In response, the revised report explicitly states that continuing to shelter in place after three days is a “basic” policy.

The report also includes specific examples of situations where temporary outings would be possible for evacuees during the shelter-in-place period.

Residents under such an order should be allowed to go out for purposes essential to maintaining their lives, such as getting daily necessities, visiting hospitals and clearing snow from houses, the report said.

Going outside should also be permitted for activities of private businesses engaged in operating medical and elderly care facilities, the report added.

"It's necessary to work even more closely with other government agencies" over details of assistance to be given to residents under shelter-in-place orders, NRA Chairman Shinsuke Yamanaka told a news conference Wednesday.

Even after the guidelines are revised, "new problems may emerge that need to be considered. We'll continue making improvements," he also said.