power – strom und macht

The Cause of Radiation Will Be Investigated

Susanne Gerber


The record-high radiation reading at Tokyo Electric Power Co.’s wrecked Fukushima nuclear plant north of Tokyo won’t delay work on containing the crisis, Goshi Hosono, the Japanese minister in charge of the disaster, said. The utility known as Tepco said yesterday it recorded radiation of 10 sieverts per hour, the maximum reading on the Geiger counter used and the highest since the plant was hit by an earthquake and tsunami on March 11. A single dose of 10 sieverts would kill a person “within a few weeks,” according to the website of the World Nuclear Association. High radiation has previously impeded attempts to replace cooling systems to bring three melted reactors and four damaged spent fuel ponds under control because of danger to workers. The latest readings were taken at the base of the ventilation stack for reactors No. 1 and No. 2, which are away from the site’s main working areas, Tepco said. The cause of the radiation at that area will be investigated today. The amount of radiation detected was the highest the machines used were capable of reading, Junichi Matsumoto, a general manager at the utility, said yesterday, indicating the dose could have been higher than 10 sieverts an hour. The radiation is probably coming from materials that flowed through to the stack during early failed attempts to release pressure in containment vessels and vent hydrogen gas to prevent the explosions that damaged reactor buildings, Matsumoto said today. High levels of radiation weren’t found at the ventilation stack for reactors No. 3 and No. 4, Matsumoto said. There aren’t plans to look for other so-called hot areas, he said. “Because of the risk of exposure among workers, we are not planning to send workers just to find high-radiation zones,” Matsumoto said.  There were about 2,760 workers at the plant yesterday, he said. “There is probably no immediate effect on on-site works to achieve cold shutdown, but the utility has to deal with the material in future when decommissioning the plant,” said Hironobu Unesaki, a nuclear engineering professor at Kyoto University in western Japan. Tepco has been criticized by the government for withholding radiation data and other missteps that have compounded the crisis, which led to 160,000 people being evacuated from near the plant. Radiation leaks from the Fukushima reactors have spread over 600 square kilometers, Tomio Kawata, a fellow at the Nuclear Waste Management Organization of Japan, said in a research report published on May 24 and given to the government. Radioactive soil in pockets of areas outside the exclusion zone around the plant have more than reached the level as in Chernobyl following a reactor explosion in the former Soviet Union territory 25 years ago. The threats to Japan’s food chain are also multiplying as radioactive cesium emissions from the Fukushima plant spread. Beef is the latest product to be contaminated and the government has banned shipments from parts of the country after tainted meat was put on sale in supermarkets. The Fukushima plant, about 220 kilometers (137 miles) north of Tokyo, had reactor meltdowns after the earthquake and tsunami knocked out power and backup generators. Tepco on April 17 set out a so-called road map to end the crisis by January, aiming to bring down radiation levels at the plant within three months and then achieve a so-called cold shutdown where reactor temperatures fall below 100 degrees Celsius (212 degrees Fahrenheit).


Filed under: Danger, Fukushima, Radiation

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