著者

鑛山 宗利 鈴木 茂之 蜂谷 欽司 小野 文一郎 多田 幹郎 佐藤 公行

出版者

公益社団法人 日本アイソトープ協会

雑誌

RADIOISOTOPES (ISSN:00338303)

巻号頁・発行日

vol.44, no.5, pp.310-314, 1995-05-15 (Released:2010-09-07)

参考文献数

6

被引用文献数

1 1 1

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Environmental ionizing radiations were surveyed in Okayama city during December of 1992, using a NaI (Tl) scintillation survey meter (TCS-161; Aloka, Japan) and a NaI (Tl) γ spectrometer (JSM-102; Aloka, Japan) ; measerments were carried out in fine days.Equivalent dose rate of environmental ionizing radiations was in the range of 0.048-0.171μSv/h, and the average was 0.082±0.019μSv/h. The dose rate was higher in hills than in fields. Therefore, it appears as if rocks have more radioactive materials than soils do.The distribution of the dose rates was analyzed from geological points of view. Mesozoic and Paleozoic layer was in the range of 0.067-0.095μSv/h, and the average was 0.080±0.008μSv/h. Rhyolitic layer was in the range of 0.076-0.105μSv/h, and the average was 0.088±0.010μSv/h. Granitic layer was in the range of 0.057-0.171μSv/h, and the average was 0.098±0.022μSv/h. Neogene Period layer was in the range of 0.057-0.114μSv/h, and the average was 0.076±0.015μSv/h. Quaternary Period layer was in the range of 0.048-0.114μSv/h, and the average was 0.076±0.013μSv/h.By γ spectrometry, 40K, 208Tl, 212Bi, 214Bi, and 228Ac were detected at Mt. Kaigara (0.171μSv/h), Tsushima (0.076μSv/h) and Fujita (0.048μSv/h), especially, 226Ra was detected at Mt. Kaigara. It seems that 40K was distributed uniformly in Okayama city area. Thas, the difference in the dose range is attributable to nuclides other than 40K.Now, we conclude that there has been no change of the dose rates of environmental radiation in Okayama city these 10 years.