TOKYO — Japan is letting up to 16,000 people back into their homes around its leaking nuclear power plant, easing restrictions in the no-go zone for the first time since last year’s disasters.

They won’t be allowed to stay overnight, some must wear protective gear, and it’s unclear how many will return at all, but the step is crucial to permanently resettling towns vacated since the the March 11, 2011, earthquake and tsunami devastated the Fukushima Dai-ichi plant and caused meltdowns in three of its reactors.

A  12-mile zone around the plant has been off-limits to about 100,000 residents for more than a year because of radiation contamination. But the plant was declared stable in December, with leaks substantially subsiding, and that let officials focus on how to clean up the contamination and allow some people to return.

On Friday, the government said it was rearranging the evacuation zone based on three categories of contamination, rather than by distance. The strict perimeter was long criticized as an inexact measure of safety, as radiation levels varied widely in the area and some hotspots existed outside the area.

The change affects three of the 11 municipalities inside the former evacuation zone.

“The reorganization would be the foundation for the reconstruction of the affected towns. We will thoroughly discuss how we can best accommodate their needs,” said Economy and Trade Minister Yukio Edano, who announced the step late Friday.

Sunday, Tamura will allow all residents to visit their homes part-time without protection or permission – but not sleep there just yet, and the town of Kawauchi will allow residents to visit, though they must wear protective gear in some areas.