Fukushima Plant Released Record Amount of Radiation

By Beth Thomas - Oct 31, 2011 12:07 PM GMT+0700

The destroyed Fukushima nuclear plant in Japan was responsible for the biggest discharge of radioactive material into the ocean in history, a study from a French institute said.

The radioactive cesium that flowed into the ocean from the Fukushima Dai-Ichi nuclear plant was 20 times the amount estimated by its owner, Tokyo Electric Power Co., according to the study by the Institute for Radiological Protection and Nuclear Safety, which is funded by the French government.

It’s the second report released in a week calling into question estimates from Japan’s government and the operator of the plant that was damaged in the March earthquake and tsunami. Tokyo Electric’s Fukushima station may have emitted more than double the company’s estimate of atmospheric release at the height of the worst civil atomic crisis since Chernobyl in 1986.

The oceanic study estimates 27,000 terabecquerels of radioactive cesium 137 leaked into the sea from the Fukushima plant, north of Tokyo.

Tepco is aware of the estimate from the institute through media reports and has no comment, spokesman Hajime Motojuku said today by phone.

Cesium 137 is a source of concern for public health because the radioactive isotope has a half-life of 30 years.

A becquerel represents one radioactive decay per second and involves the release of atomic energy, which can damage human cells and DNA. Prolonged exposure to radiation can cause leukemia and other forms of cancer, according to the World Nuclear Association. A terabecquerel is 1 million times 1 million becquerels.

The three melted reactors and at least one damaged spent- fuel pool may have emitted 35,800 terabecquerels of cesium 137 into the atmosphere at the height of the disaster, according to a study in the Atmospheric Chemistry and Physics journal. Japan’s nuclear regulator in June said 15,000 terabecquerels of cesium 137 was discharged.

The estimated amount is about 42 percent of that released into the atmostphere in the Chernobyl explosion in 1986, according to the study.

To contact the reporter on this story: Beth Thomas in Hanoi at bthomas1@bloomberg.net

To contact the editor responsible for this story: Peter Langan at plangan@bloomberg.net