by Debora MacKenzie, newscientist.com, 24 March 2011:
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 daily at 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.
The organisation set up to verify the Comprehensive Nuclear-Test-Ban Treaty (CTBT) has a global network of air samplers that monitor and trace the origin of around a dozen radionuclides, the radioactive elements released by atomic bomb blasts – and nuclear accidents. These measurements can be combined with wind observations to track where the radionuclides come from, and how much was released. Read more>>