Radon and Thoron exhalation rate map in Japan

摘要

Measurements of radon and thoron exhalation rates have been done using the radon andthoron exhalation rate measuring instrument adopting the accumulation method. We obtained the111 data in the 40 sites of the 14 prefectures in Japan. The arithmetic average value of the radonand thoron exhalation rates by all 111 data were obtained to be 8.6 mBq.m~(-2).s~(-1)and 0.80 Bq.m~(-2).s~(-1),respectively, andwehave reported the radon and thoron exhalation rates in relation to thegeological features. The relation between the exhalation rate and geology was shown that theexhalation rate had an increasing tendency in order of basic rock, neutral rock and acidic rock. Wemade the nationwide exhalation-rate map using the survey data of exhalation-rate of radon andthoron and the geological distribution map.