One of the municipalities that hosts the crisis-hit Fukushima No. 1 nuclear plant is considering lifting restrictions on daytime access in spring 2020 to an area being rebuilt in the town center, sources close to the matter said Thursday.

The town of Futaba, Fukushima Prefecture, where units Nos. 5 and 6 of the complex are located, became a ghost town after the 2011 disaster due to high levels of radiation. Those wishing to visit need to apply in advance for permission to enter and must pass through a checkpoint.

But such restrictions would be lifted during the daytime for access to a special zone several kilometers from the Fukushima plant on the Pacific coast, where government-funded decontamination and reconstruction work is underway, with the aim of evacuees returning in the spring of 2022.

To lift the restrictions, the town will have to meet government criteria to be unveiled by the end of the year. If realized, the move will pave the way for the town to be rebuilt.

After the massive earthquake and tsunami triggered the world’s worst nuclear catastrophe since the 1986 Chernobyl disaster, the whole of Futaba was designated a no-go zone for residents, with radiation levels exceeding 50 millisieverts per year.

The town’s plan to mark the special zone as a reconstruction hub was endorsed by the central government in September last year. The town said at the time that in most of the area radiation levels had fallen below 20 mSv per year, with figures around Futaba Station brought down below 5 mSv per year.

Decontamination work has been conducted to make sure radiation levels will be below 20 mSv per year throughout the special zone by the spring of 2020. The government eventually aims to lower the levels below 1 mSv per year.

The International Commission on Radiological Protection sets radiation exposure under normal situations at 1 mSv per year and says 100 mSv of exposure over a lifetime would increase the possibility of developing cancer by up to 1 percent.

Under emergency situations, the ICRP sets a limit of 20-100 mSv of annual radiation exposure.

In the special zone, which will occupy about 560 hectares, or 10 percent of the town, residential areas and commercial facilities will be built. Futaba envisions some 2,000 residents will eventually live in the area.

With more residents and construction workers expected to come to the area, the town is likely to discuss measures with the central government to beef up surveillance through the use of security cameras or patrols.

Five other municipalities near the Fukushima No. 1 plant aim to build similar reconstruction hubs for the return of their own evacuees.

All six municipalities are planning to have evacuation orders lifted in the hub zones by the spring of 2023 but Futaba is the first to announce plans for free access during daytime.

The Fukushima No. 1 plant spewed a massive amount of radioactive materials after a magnitude 9.0 earthquake triggered tsunami that flooded the facility on March 11, 2011.

Reactor Nos. 1 to 3 suffered fuel meltdowns, while hydrogen explosions damaged the buildings housing units Nos. 1, 3 and 4. Reactor Nos. 5 and 6 achieved a cold shutdown after several days.

The disaster left more than 18,000 people dead or missing. As of November, more than 54,000 people were still unable to return to their homes.