Studies on radioactivities of dust samples in the air at high altitudes

The radioactivity concentrations of airborne dust samples were studied. The samples had been collected at high altitude by the Japan air Self-Defense Force from April 2012 to March 2013. The obtained data were gross beta radioactivity analysis and gamma nuclide analysis. It is shown that cesium 137 was mainly detected at the 10 km and 3 km altitude of central area of Japan in over half of the samples. Gaseous radioiodine was not detected in all the samples. Radioactive xenon gas was not detected in regular samples collected in September and March. On the other hand, it was detected in a particular sample collected in February, but it was within background level. The report was already submitted with regard to the results on radionuclide measurements of Technical Research and Development Institute executed to examine 'the nuclear emergency situation at Fukushima Daiichi and Daini nuclear power plants' after 'Tohoku Region Pacific Ocean Earthquake' on March 11, 2011. (author)