http://www.cbc.ca/world/story/2006/10/13/radiation-north-korea.html
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CHINA AND JAPAN FOUND NO COMPELLING EVIDENCE IN THEIR AIR SAMPLES.
ANY THEORIES, FREEPERS, AS TO WHAT MIGHT BE GOING ON HERE?
ANY THEORIES, FREEPERS, AS TO WHAT MIGHT BE GOING ON HERE?
No one seems willing to identify the nuclides.
Possibly China and Japan were looking for particulate materials such as strontium 90, barium 143, etc.
Later tests by some may have found krypton 90 or other gaseous nuclides such as xenon isotopes. These are not found in Nature, so would be indicative of a fisson reaction..NOT neccesarily from a critical mass, though. A poor yeild could still produce some.
Still, we do not know WHAT they found, if anything.