Here's another article I found: "Fukushima Radioactive Fallout Nears Chernobyl Levels"

17:14 24 March 2011 by Debora MacKenzie

"The cumulative releases from Fukushima of iodine-131 and cesium-137 have reached 73% and 60% respectively of the amounts released from the 1986 Chernobyl accident. These numbers were reached independently from a monitoring station in Sacramento, CA, and Takasaki, Japan. The iodine and cesium releases are due to the cooking off of the more volatile elements in damaged fuel rods."

Japan's damaged nuclear plant in Fukushima has been emitting radioactive iodine and caesium at levels approaching those seen in the aftermath of the Chernobyl accident in 1986.

Austrian researchers have used a worldwide network of radiation detectors – designed to spot clandestine nuclear bomb tests – to show that iodine-131 is being released at daily levels 73 per cent of those seen after the 1986 disaster. The daily amount of caesium-137 released from Fukushima Daiichi is around 60 per cent of the amount released from Chernobyl.

The difference between this accident and Chernobyl, they say, is that at Chernobyl a huge fire released large amounts of many radioactive materials, including fuel particles, in smoke. At Fukushima Daiichi, only the volatile elements, such as iodine and caesium, are bubbling off the damaged fuel. But these substances could nevertheless pose a significant health risk outside the plant.



In the 10 days it burned, Chernobyl put out 1.76 × 1018 becquerels of iodine-131, which amounts to only 50 per cent more per day than has been calculated for Fukushima Daiichi. It is not yet clear how long emissions from the Japanese plant will continue.

Similarly...caesium-137 emissions are on the same order of magnitude as at Chernobyl. The Sacramento readings suggest it has emitted 5 × 1015 becquerels of caesium-137 per day; Chernobyl put out 8.5 × 1016 in total – around 70 per cent more per day.

"This is not surprising," says Wotawa. "When the fuel is damaged there is no reason for the volatile elements not to escape," and the measured caesium and iodine are in the right ratios for the fuel used by the Fukushima Daiichi reactors.

Also, the Fukushima plant has around 1760 tonnes of fresh and used nuclear fuel on site, and an unknown amount has been damaged. The Chernobyl reactor had only 180 tonnes.


[link to www.newscientist.com]