Abstract
Radioactivity in air have been surveyed at Hiroshima after the reactor accident of Fukushima Daiichi Nuclear Power Plant on March 11, 2011. Sampling was started on March 20 with a high volume air sampler (SHIBATA HVA-500N) with 500 l/min for 8 hours in the daytime. A glass fiber filter (TOYO GB100R) was used for air sampling. Gamma-ray measurements were performed with a low-background Ge detector (EG&G ORTEC GWL-120230-S) To reduce the background gamma-rays from radon progeny nuclei (214Pb, 214Bi), the measurement was started after 4 h from the end of sampling. Radionuclide 131I was first observed on March 30, thereafter 134Cs, 137Cs and 132Te were observed. The concentration of radionuclides were reached at maximum on April 7 and April 17 again, then gradually decreased. Radioactivity was not observed at the end of April any more. The maximum concentrations were 0.0066 Bq/m3 for 131I, 0.0078 Bq/m3 for 137Cs, 0.0068 Bq/m3 for 134Cs and 0.00011 Bq/m3 for 132Te. 131I was also observed in rain water on April 8 with concentration 0.044 Bq/l. Comparison of observed radionuclide and those of Chernobyl reactor accident will be given.
