The national government is reviewing with local governments the possibility of establishing a “caution zone” around the power plant with a radius of 12 miles said Yukio Edano, the chief secretary of Japan’s cabinet. Such a zone would be legally enforceable, in contrast with the current evacuation, which is technically voluntary.
As most radiation releases from the Fukushima Daiichi Nuclear Power Station have been stopped, some families have been re-entering the area in recent days to remove belongings and some journalists have been exploring it. Dozens of families never left after the initial evacuation was ordered in stages nearly six weeks ago, following an earthquake and tsunami on March 11.
Growing activity in the evacuation area has prompted concern among evacuees that their homes may be robbed while they are away. Nuclear power experts have been debating whether the continued movement of people, livestock and vehicles in the area will make it harder to decontaminate after the nuclear power plant has been fully stabilized.
Noriyuki Shikata, a senior government spokesman, said on Tuesday that the government did not have the legal authority to prevent people from entering and leaving the evacuation zone, nor the legal authority to evict those who stayed behind. Media reports have suggested that as many as 200 households are still occupied in the zone, mainly elderly people who refuse to live at evacuation centers in gymnasiums or farmers who refuse to abandon their livestock.
Plans for a caution zone were reported by the Asahi Shimbun newspaper, which said that the government also intended to allow residents to make brief trips into the zone to recover essentials from their homes.
The Sankei Shimbun newspaper reported on its Web site on Wednesday morning that residents of Minami-Soma city, which lies partly inside the northern side of the evacuation zone, were being given fliers warning that a legally enforceable caution zone could be created.
A spokesman for the Fukushima Prefecture police, whose jurisdiction encompasses the evacuation zone, said that the police have done spot checks on 3,378 addresses in the area during the past three weeks and found people at 63 sites; those people were asked to leave. According to the Japanese cabinet, there were 78,200 residents of the area inside the 12-mile radius before the earthquake, tsunami and nuclear accident.
Mr. Edano, the second-ranking government official in Japan, said at a follow-up news conference on Wednesday afternoon that Prime Minister Naoto Kan would travel on Thursday to Fukushima to meet the prefecture’s governor and visit evacuation centers in two cities in the prefecture. Mr. Edano declined to predict whether a caution zone would be imposed.
Decontamination of a large area after a nuclear accident consists of very carefully mapping the “hot spots” where wind and rain may have concentrated radioactive fallout. Contaminated objects are then sent to a specially lined landfill; even the dirt may have to be dug up if contamination is high enough.
Michael Friedlander, a former nuclear power plant operator in the United States and nuclear emergency specialist who now lives in Hong Kong, said in interviews last week and this week that it was very important to prevent unnecessary activity in the evacuation zone. He contended car tires and other movement could result in smearing around the radioactive dust from the invisible hot spots, making it necessary to decontaminate other areas as well or leaving other areas with low levels of contamination.
But Michael Corradini, the chairman of engineering physics at the University of Wisconsin, said that with power crews already setting up electricity transmission lines across the evacuation zone to the damaged power plant, and with heavy repair equipment being brought in as well to the power plant, the movement of private individuals and their vehicles would probably not have much additional effect in spreading out the hot spots.
Another 62,400 people lived between 12 and 19 miles from the power plant. People living inside the larger area were initially told to stay indoors, but have since been asked to leave voluntarily, along with residents of five other communities outside the zone that also received some radioactive fallout because of wind and rain patterns. The cabinet has not released an estimate for the population of the other five communities.
After the Chernobyl nuclear accident in 1986, the former Soviet Union established a more stringently enforced exclusion zone with an initial radius of about 19 miles. The exact boundaries of the zone were later adjusted to reflect actual patterns of fallout. Wind and rain had pushed particularly heavy fallout to the north of the reactor that caught fire.
Japan has been fortunate in that weather patterns appear to have pushed much of the radiation straight east and out to sea, with the exception of one plume that fell on land to the northwest of the reactor.
Many of the wind gauges and other meteorological equipment close to the site were destroyed by the tsunami and earthquake. Masanori Shinano, a technical counselor at Japan’s Nuclear Safety Commission, said last week that the government had needed to estimate wind direction to calculate the total radiation released by the accident. The agency looked at weather forecasts for those days around the Fukushima area, which are generated from computer models using other weather stations, and concluded from the forecasts that the wind was mainly blowing out to sea during the days of the greatest release of airborne radioactive material.
The commission, a panel of independent experts, estimates that the total radiation released by the Fukushima accident was one-sixth of that at Chernobyl. Japan’s Nuclear and Industrial Safety Agency, which has a history of being close to the nuclear industry, estimates that the total release was a tenth of Chernobyl’s.
Ken Ijichi, Moshe Komata and Kantaro Suzuki contributed reporting.
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