Tomohiro Ohsumi/Bloomberg News
Buyers inspected fresh fish before an auction in Tokyo last Wednesday.
By ANDREW POLLACK, KEN BELSON and KEVIN DREW
Published: April 5, 2011
TOKYO — The company that runs Japan’s crippled nuclear power plant announced Wednesday that it had stopped the leak of tons of highly radioactive water into the ocean discovered over the weekend. The news came a day after the company said the levels of radioactive material in the seawater near the plant were measured at several million times the legal limit.
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Shiho Fukada for The New York Times
On Monday, people in Otsuchi, Japan, in Iwate Prefecture, searched for belongings in homes damaged by the March 11 tsunami.
But even the rare bit of good news from the plant was unlikely to calm worries about the growing contamination in nearby coastal waters. On Tuesday, the government said that a fish caught about 43 miles away was found to have high levels of radioactive iodine 131, prompting it to announce radiation safety levels for fish.
And the company has been flushing thousands of tons of relatively low-level radioactive water into the Pacific to make room in storage containers for increasing amounts of far more contaminated runoff. The runoff resulted from workers’ pouring massive amounts of water on reactors and spent fuel-rod pools to keep them from overheating after their normal cooling systems failed.
The water being intentionally released contains about 100 times the legal limit of radiation, said the Tokyo Electric Power Company, the plant’s operator. The more contaminated water that it hopes to contain has about 10,000 times the legal limit.
The small fish caught Friday — before the intentional dumping began — had 4,080 becquerels of iodine 131 per kilogram. The new standards allow up to 2,000 becquerels of iodine 131 per kilogram, the standard used for vegetables in Japan, but it was unclear how the government would enforce the new rules.
The fish also contained cesium 137, which decays much more slowly than iodine 131, at a level of 526 becquerels per kilogram.
“Clearly the fish are consuming highly radioactive food,” said Paul G. Falkowski, a professor of marine, earth and planetary sciences at Rutgers University. But Professor Falkowski emphasized that even those levels were not likely to present health hazards in Japan or elsewhere, since fishing is restricted in Japan and these levels of radiation are not likely to travel far.
Still, experts on radiation in seafood said it was nearly impossible to get a full sense of the scope of the environmental and health risks until the Japanese released information on radiation levels in more species of fish and seaweed and in a greater number of locations. Measurements in the seawater are often not a good indication of how much radiation may be entering the food chain, scientists say.
Fish and seaweed can concentrate radioactive elements as they grow, leading to levels that are higher, sometimes far higher, than in the surrounding water. Seaweed can concentrate iodine 131 10,000-fold over the surrounding water; fish concentrate cesium 137 modestly.
The announced standards for fish came hours after Tokyo Electric said it had found iodine 131 in seawater samples at 200,000 becquerels per cubic centimeter, or five million times the legal limit. The samples were collected Monday near the water intake of the No. 2 reactor of the Fukushima Daiichi Nuclear Power Station.
The samples also showed levels of cesium 137 to be 1.1 million times the legal limit, according to the Japanese public broadcaster NHK. Cesium remains in the environment for centuries, losing half its strength every 30 years.
The Monday sampling of seawater showed a drop in radioactive iodine levels since Saturday when, the company said, the level of iodine 131 was 300,000 becquerels per cubic centimeter.
Meanwhile, the death toll from the March 11 9.0-magnitude earthquake and tsunami rose to 12,341 on Tuesday, the country’s National Police Agency said. More than 15,000 people are missing, and more than 160,000 are in temporary shelters across the country, the agency said.
The crisis at the power station, now in its fourth week, has shaken public confidence in Tokyo Electric. Its share prices plunged to an all-time low on Tuesday over concern by investors about the financial burden of the work being carried out at Daiichi.
The company has lurched from crisis to crisis since the plant’s cooling systems stopped working after the quake and tsunami. Even the news about stopping the leak came after days of false starts, including attempts to plug a large crack in a maintenance pit with more than 120 pounds of sawdust, three garbage bags of shredded newspaper and about nine pounds of a polymeric powder that absorbs water.
In the end, the company said it had succeeded in stopping the leak using sodium silicate, which acts as a cement.
The country’s trade and industry minister, Banri Kaieda, said Tuesday that 60,000 tons of radioactive water was thought to be flooding the basements of the plant’s reactor buildings and underground tunnels, according to the Kyodo news agency.
A government panel suspended work on Tuesday on revising the country’s policy platform on nuclear power, according to local news media reports, saying the crisis needed to be resolved before Japan could publicly assess its nuclear power policies.
The Ministry of Economy, Trade and Industry directed Tokyo Electric to start paying “condolence money” to 10 communities near the company’s Fukushima Daiichi plant. In a news conference, Tokyo Electric said all but one community had accepted the money, which is meant to help evacuees but does not recognize responsibility in the disaster.
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