Authorities have battled to prevent radioactive contaminants from escaping the six-reactor facility following a March 11 earthquake and tsunami that left more than 20,000 people dead or missing in Japan. Four days into the crisis, an air current that had been pushing radioactive material seaward turned northwest and prompted warnings from nation's radioactive plume modeling system, dubbed the System for Prediction of Environmental Emergency Dose Information, that contaminants would move toward Iitate.
Japan's Fukushima prefecture provided warning by March 15 of elevated atmospheric contaminant concentrations in Iitate, where roughly 6,000 people lived. The nation's Education Ministry, followed by other entities, began measuring radiation levels around the village on March 16, and regular air samples were eventually being collected at 36 locations in the area. Tokyo put the data online without comment.
Radiation levels in Iitate appeared significant to Toshimitsu Honma, a senior official with Japan's Nuclear Safety Research Center who also sits on the emergency committee of the Japanese Nuclear Safety Commission. Still, the village's cumulative radiation level had not yet reached the government's evacuation threshold of 50 millisieverts; Tokyo advised residents to remain inside in areas where cumulative radiation levels fell between 10 and 50 millisieverts.
"We spent a lot of time debating because we knew we were making a very profound decision," Honma said, referring to a potential evacuation order. "The real problem was the 50 millisievert rule," he said, adding he supported removing Iitate's residents as of early April.
Radioactivity in Iitate began to decline after plateauing on March 17 and 18, but contamination persisted and cumulative exposure continued to increase. One isolated area received 28 millisieverts of radiation in the first 17 days of the crisis, and the Nuclear Safety Commission projected it would receive 35 millisieverts over time.
The government, which had acted within days to remove residents from a 12-mile ring around the plant, did not call for Iitate's evacuation as disagreement persisted among Nuclear Safety Commission members over the extent of danger to the village. "We are aware that there are some areas outside (the evacuation zones) that are contaminated, but it is our judgment that there won't be health consequences as a result," said Haruki Madarame, the commission's chairman.
The International Atomic Energy Agency, though, on March 30 said an analysis of ground material turned up contaminants exceeding its evacuation standard. Japan on April 22 called for residents to leave Iitate and four other locations where radioactive materials from the plant had collected unevenly (Yuka Hayashi, Wall Street Journal, Aug. 16).
Meanwhile, local officials for the Fukushima prefecture towns of Futaba and Okuma on Monday said former residents would be permitted between August 26 and September 1 to temporarily return to properties within 1.9 miles of the damaged nuclear plant, Kyodo News reported (Kyodo News/Mainichi Daily News, Aug. 16).
Elsewhere, China indicated it would bolster radiation monitoring efforts in ocean water east of the nuclear plant and in the East China Sea, China Daily reported. The initiative would seek to gauge the effect of radioactive contaminants from the facility on the ocean habitat and on seafood from the region, according to the Chinese State Oceanic Administration's environmental protection department.
Ocean water collected previously by the agency contained 300 times the naturally occurring concentration of radioactive cesium and 100 times the natural concentration of radioactive strontium, according to data made public on July 29 (Wang Qian, China Daily, Aug. 16).
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