Fukushima Cesium Leak Equal to 168 Hiroshima A-Bombs - International Environment

Fukushima Cesium Leak Equal to 168 Hiroshima A-Bombs
by staff report via gan - Japan Times Sunday, Aug 28 2011, 8:05am
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The Nuclear and Industrial Safety Agency provided the estimate at the request of a Diet panel but noted that making a simple comparison between an instantaneous bomb blast and a long-term accidental leak is problematic and could lead to "irrelevant" results.

The report said the crippled Fukushima No. 1 plant has released 15,000 terabecquerels of cesium-137, which lingers for decades and can cause cancer, compared with the 89 terabecquerels released by the U.S. atomic bombing of Hiroshima.

The report estimated each of the 16 isotopes released by the "Little Boy" bomb and 31 of those detected at the Fukushima plant. NISA has said the radiation released at Fukushima was about one-sixth of that released during the 1986 Chernobyl disaster.

"Little Boy," dropped Aug. 6, 1945, destroyed most of the city and eventually killed as many as 140,000 people.

Most of the Hiroshima victims were killed in the initial heat wave, while others died from the neutron rays generated by the midair explosion or the deadly radioactive fallout. No one has died yet from radiation emitted by the Fukushima plant, where explosions caused by unvented hydrogen blew apart the upper halves of the reactor buildings but left the reactor cores in place.

The report estimated that iodine-131, another isotope that accumulates in the thyroid gland, and strontium-90, which has a 28-year half-life and can accumulate in bones, leaked from the plant in amounts roughly equal to 2½ higher than the Hiroshima atomic bomb.

A separate government report released Thursday said that 22 percent of cesium-137 and 13 percent of iodine-131 released from the plant landed on the ground, with the remainder landing either in the ocean or outside its simulation area.

The National Institute for Environmental Studies said its simulation of aerial flow, diffusion and deposition of the two isotopes released from the tsunami-hit plant showed their impact reached most of eastern Japan, stretching from Iwate Prefecture in the north and to Tokyo and Shizuoka Prefecture further south.

The study also showed that iodine-131 tended to spread radially and cesium-137 tended to create "hot spots."

© 2011 The Japan Times

Greenpeace said on Monday that schools and surrounding areas located 60 km (38 miles) from Japan's tsunami-hit nuclear power plant were unsafe for children, showing radiation readings as much as 70 times internationally accepted levels.

The environmental group took samples at and near three schools in Fukushima city, well outside the 20 km exclusion zone from Tokyo Electric Power's stricken Fukushima Daiichi nuclear complex in Japan's northeast.

"No parent should have to choose between radiation exposure and education for their child," said Kazue Suzuki, Greenpeace Japan's anti-nuclear project head.

The government had already taken steps to decontaminate schools in Fukushima prefecture, where the crippled plant has been leaking radiation since it was hit by the March 11 earthquake and tsunami.

Calling the measures "deplorably late and inadequate," Greenpeace said it had found average dose rates above the maximum allowed under international standards, of 1 millisievert per year, or 0.11 microsievert per hour.

Japan's education ministry on Friday set a looser standard, allowing up to 1 microsievert per hour of radiation in schools.

Greenpeace said that inside a high school it tested, the reading was 0.5 microsievert per hour, breaching international standards even after the government's clean-up.

At a staircase connecting a school playground to the street, it found radiation amounting to 7.9 microsieverts per hour, or about 70 times the maximum allowed, exceeding even Japan's own standard.

Greenpeace urged the government to delay reopening the schools as planned on Sept. 1 after the summer break and relocate children in the most affected cities until decontamination was complete.

Fukushima city dismissed Greenpeace's calls, saying the schools were safe under the government's norms.

"We're finished decontaminating the schools, and they no longer have high radiation levels," city official Yoshimasa Kanno said. He added that postponing the opening of more than 100 schools in the city based on Greenpeace's findings of "only three" would be unreasonable.

RADIATION TO PERSIST FOR YEARS

Despite the government's reassurances, parents have removed thousands of children from schools in Fukushima since the disasters, fearing damage to their health.

Underscoring such concerns, the government said this month that 45 percent of children living outside the evacuation zone in Fukushima were exposed to low levels of radiation though it was within safety levels.

Greenpeace, which took its samples Aug. 17-19, did not say how long it might take to rid the areas of harmful levels of radiation.

But Jan van de Putte, its radiation expert, noted that cleaning up in the Ukrainian capital of Kiev, about 100 km from Chernobyl, required hundreds of thousands of workers toiling over several months.

A vast area is still uninhabitable around the Chernobyl plant 25 years after the world's worst nuclear disaster, and experts have estimated Japan's decontamination efforts could cost as much as 10 trillion yen ($130 billion).

"We expect that the radiation levels would persist for a long period of time," van de Putte said. ($1 = 76.855 Japanese Yen) (Editing by Chang-Ran Kim and Chris Gallagher)

© 2011 Thomson Reuters

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