Photo/IllutrationA gate is set up on a national road in Okuma, Fukushima Prefecture, restricting entrance to "difficult-to-return zones." Permits from the central government are required to enter the areas. (Noriyoshi Ohtsuki)

For the first time since the 2011 nuclear disaster in Fukushima Prefecture, the government will lift the designation of some "difficult-to-return zones" around the crippled nuclear plant.

The rescinding is expected to be done gradually from around 2021. By that time, the government plans to undertake intensive decontamination work in central districts of municipalities, where residents will likely return, and districts along main roads.

The "difficult-to-return zones," which cover a total of 337 square kilometers, are areas where the radiation level exceeded 50 millisieverts per year after the accident at the Fukushima No. 1 nuclear plant. Those areas are off-limits, in principle.

In some of the areas, however, radioactive contaminants have been washed away by rain or blown away by wind. Radiation from those substances has also dissipated naturally.

In front of the Environmental Radioactivity Monitoring Center of Fukushima in the central district of Okuma town, the radiation level is now about 9 millisieverts per year, about one-fifth the level of five years ago.

According to the policies of the government and the ruling parties, if radiation levels are reduced to 20 millisieverts or lower in some areas due to decontamination work, people are allowed to live there.

Of the areas, those where residents or workers for decommissioning of crippled nuclear reactors are expected to live will be subject to intensive decontamination work along with areas on both sides of main roads.

The government and the ruling parties will discuss the lifting of "difficult-to-return zones" with seven municipalities, including Okuma, and will make the official decision in August.

However, even if the designation is lifted, it is uncertain if residents will return to their homes.

According to the annual survey conducted by the Reconstruction Agency on evacuees, only about 10 percent of households evacuating from four municipalities around the nuclear plant are hoping to return home.

Before the nuclear crisis occurred, about 24,000 people of 9,000 households were living in areas that are currently designated as "difficult-to-return zones."