Fukushima Update

8% of Japan Contaminated

Post-Fukushima Radiation Mapped

Cesium in soil a problem for agriculture

By Prachi Patel, IEEE Spectrum

December 2011

Three recently published academic studies show that while direct radiation exposure of Fukushima residents isn’t as high as was initially feared, soils across northeastern Japan are contaminated and could affect public health for decades through the produce farmed there. The research, combined with a map of soil radiation-which was based on measurements made during helicopter flights and released by Japan’s science ministry-shows substantial soil contamination in the prefectures of Fukushima and its neighbors: Miyagi and Iwate to the north, Ibaraki and Chiba to the south, and Tochigi and Gunma to the southwest.

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The government’s radiation map shows high levels of radioactive cesium in Fukushima and surrounding prefectures. Some spots have levels between 100 000 and 600 000 becquerels per square meter (148 000 was the standard used for mandatory resettlement after the Chernobyl disaster). That the cesium is mostly in chloride form makes matters worse, Moulder says: “It’s water soluble, easily taken up by the body, and very well distributed in the body-all the things you don’t want.” The contamination could also irradiate anyone who walks on the ground, he adds.

According to the Japanese newspaper The Asahi Shimbun, the science ministry says that about 8 percent of the country’s land has been contaminated with levels higher than 10 000 Bq/m2, a threshold that Japan’s science ministry defines as affected by a nuclear accident. The newspaper also reports that the government has confirmed radioactive materials from the meltdown in all prefectures, including Okinawa, which is 1700 kilometers from the power plant.

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“There’s really no good way to clean up cesium-137 from a large area,” Moulder says. “To decontaminate a playground, you can scoop up the soil and lay down new asphalt, but you can’t scoop up a whole rice field. You’ll then have to dispose all that radioactive waste. These areas could become inhabitable but still couldn’t be used for agriculture.”

Cesium-137 is responsible for radiation in the Chernobyl dead zone.  It has a half life of 30 years.

Ocean contamination

Fukushima nuclear fallout spread through oceans, researchers say

MOST of the radioactive fallout from the disaster at the Fukushima nuclear plant dropped into the ocean and began circling the planet, Japanese researchers say.

AFP

November 17, 2011 8:02PM

Up to 80 per cent of the caesium released by the Fukushima Daiichi power plant after the March 11 disaster landed in the Pacific and made its way into other oceans around the world, scientists at the Meteorological Research Institute said.

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Researchers said the radioactive materials, including caesium-137, an isotope with a half-life of more than 30 years, were widely dispersed when they entered the oceans and each particle would measure less than one micrometre – one seventh the size of a human red blood cell.

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Using computer simulations, they calculated the material was first blown northeast over eastern Russia and Alaska, before falling into the Pacific and reaching the western coast of mainland US around March 17, Takahashi said.

The materials were believed to have completed their first around-the-globe trip by March 24, he said, adding that the results would be presented to an academic meeting in Nagoya, central Japan.

Fukushima disaster’s marine fallout

Nuclear contamination poses long-term threat to ocean ecosystem and to Japan’s fishing industry.

Steve Chao, Al Jazeera

30 Nov 2011 12:11

During the peak of Ukraine’s Chernobyl cataclysm of 1986, the Black Sea was registering 1,000 becquerels per cubic metre of water; this appears miniscule in comparison to nuclear levels at Fukushima’s peak recorded at 100,000 becquerels.

And it hasn’t stopped yet.

More Radioactive Water Leaks at Japanese Plant

By HIROKO TABUCHI and MARTIN FACKLER, The New York Times

Published: December 4, 201

(U)tility workers found that radioactive water was pooling in a catchment next to a purification device; the system was switched off, and the leak appeared to stop. But the company said it later discovered that leaked water was escaping, possibly through cracks in the catchment’s concrete wall, and was reaching an external gutter.

In all, as much as 220 tons of water may now have leaked from the facility, according to a report in the newspaper Asahi Shimbun that cited Tepco officials.

The company said that the water had about one million times as much radioactive strontium as the maximum safe level set by the government, but appeared to have already been cleaned of radioactive cesium before leaking out. Both elements are readily absorbed by living tissue and can greatly increase the risk of developing cancer.

Total Meltdown

All N-fuel may have fallen to outer vessel / TEPCO: Up to 68 tons likely melted in No. 1 reactor, eroding concrete of containment unit

The Yomiuri Shimbun

Dec. 2, 2011

In the No. 1 reactor, TEPCO believes, almost all of the about 68 tons of fuel melted. This has not only seriously damaged the bottom of the steel pressure vessel enough to create holes, but the fuel has also fallen to the concrete bottom of the containment vessel, eroding it by up to 65 centimeters.

Only 37 centimeters of concrete remains between the fuel and the vessel’s outermost steel wall in the most damaged area, TEPCO said.

That’s 25.6 and 14.6 inches for the metrically impaired.