Please view the main text area of the page by skipping the main menu.

Questions raised over nuclear evacuation plans urging residents to remain indoors

Residents of Ikata, Ehime Prefecture, disembark from a ferry after its arrival at a port in Oita Prefecture as part of a nuclear disaster evacuation drill, in November 2015. (Mainichi)

Residents living in areas hosting Japan's nuclear power plants are voicing concerns about nuclear accident evacuation plans following two recent deadly earthquakes in Kumamoto Prefecture registering a maximum 7 on the Japanese intensity scale.

The government's evacuation plans are based on the premise of some residents near nuclear plants initially remaining indoors, and having them flee to other prefectures if necessary. But questions have been raised over how effective current plans would be in the event of disasters like those that hit Tokyo Electric Power Co.'s Fukushima No. 1 Nuclear Power Plant in March 2011.

"If there were a nuclear accident, remaining indoors would be impossible. The Kumamoto Earthquake has made me even more anxious," said Ikue Yamaguchi, a 34-year-old public servant raising two children in the Kagoshima Prefecture city of Ichikikushikino. Her home is just around 15 kilometers away from the No. 1 and 2 reactors at the Sendai Nuclear Power Plant in Satsumasendai in the prefecture. The reactors are the only ones currently operating in Japan.

Before the Fukushima nuclear disaster, areas within 8 to 10 kilometer radii of nuclear power plants were designated as being subject to evacuation plans, but after the outbreak of the disaster, the areas were expanded to a 30 kilometer radius. As a result, 135 municipalities in 21 prefectures are now subject to such plans, compared with 45 municipalities in 15 prefectures before the disaster. Altogether, some 4.8 million people, or about 4 percent of the population, are subject to such evacuation plans.

Under government evacuation plans, those living within 5 kilometers of a nuclear power plant are supposed to be evacuated immediately if there are signs of a nuclear accident, while those living 5 to 30 kilometers away are to remain indoors, and then evacuate further away if there are signs that radiation levels are increasing. The Nuclear Regulation Authority says that radiation exposure can be sufficiently reduced in areas between 5 and 30 kilometers from a nuclear power plant by remaining indoors. It adds that if people in those areas go out of their way to evacuate, they could face a heighted risk of radiation exposure and health damage.

But in the case of an earthquake like the temblors that recently struck Kumamoto Prefecture, which left many homes in danger of collapsing, it would be difficult to remain indoors. And not all shelters offer stable protection, either. As of the end of March last year, 85.7 percent of public facilities in Kagoshima Prefecture supposed to be used as shelters during disasters had been reinforced against earthquakes -- a figure lower than the national average of 88.3 percent. Ehime Prefecture, which hosts Shikoku Electric Power Co.'s Ikata Nuclear Power Plant that is expected to be reactivated in late July, has the nation's third worst rate, at 79.1 percent.

If an accident were to occur at the Sendai Nuclear Power Plant in Kagoshima Prefecture, then according to estimates, it could take up to around 29 hours to evacuate some 210,000 people living within a 30 kilometer radius of the plant who would be subject to evacuation. This, however, is based on the premise of people living in areas within 5 to 30 kilometers of the plant initially remaining indoors -- if everyone were to start evacuating at once, then it is predicted that transportation networks would become congested, and evacuation would take even longer.

"Even if we were to evacuate indoors, then we would have to go outside (to receive supplies, etc.) and wouldn't be able to avoid exposure to radiation," Yamaguchi says. "I would want to evacuate immediately, but evacuation routes would probably be crowded."

Shunro Iwata, an official at the nuclear safety control division of the Kagoshima Prefectural Government, commented, "When evacuating indoors, people are not forbidden from going outside, so they can go out if the need arises. There would be no immediate effect on health (for radiation levels below the standard reading). We are not in a position to revise plans, and there is no change to the fact that this is the most reasonable approach at present."

Naoya Sekiya, a specially appointed associate professor at the University of Tokyo who is familiar with evacuation plans during disasters, said it is not realistic to base evacuation plans on the premise of people remaining indoors.

"Evacuation plans should be made with the presumption of a major earthquake cutting off roads and railways. If evacuation orders are issued to people within a five-kilometer radius of a nuclear plant, then obviously people in surrounding areas will start evacuating, too, resulting in further confusion. An evacuation plan based on the premise of people remaining indoors is not realistic," he said.

Also in The Mainichi

The Mainichi on social media