Radiological investigations at the 鈥淭aiga鈥?nuclear explosion site, part II: man-made 纬-ray emitting radionuclides in the ground and the resultant kerma rate in air

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• 作者：V. Ramzaev ; ^{V.Ramzaev@mail.ru} ; V. Repin ; A. Medvedev ; E. Khramtsov ; M. Timofeeva ; V. Yakovlev
• 关键词：Nuclear ; Explosion ; Anthropogenic ; Radionuclides ; Soil ; Dose
• 刊名：Journal of Environmental Radioactivity
• 出版年：2012
• 期刊代码：45_0265931x
• 类别：env
• 出版时间：July, 2012
• 卷：109
• 期：Complete
• 页码：1-12
• 文件大小：1427 K

摘要

Samples of soil and epigeic lichens were collected from the 鈥淭aiga鈥?peaceful nuclear explosion site (61.30掳N 56.60掳E, the Perm region, Russia) in 2009 and analyzed using high resolution 纬-ray spectrometry. For soil samples obtained at six different plots, two products of fission (¹³⁷Cs and ¹⁵⁵Eu), five products of neutron activation (⁶⁰Co, ⁹⁴Nb, ¹⁵²Eu, ¹⁵⁴Eu, ²⁰⁷Bi) and ²⁴¹Am have been identified and quantified. The maximal activity concentrations of ⁶⁰Co, ¹³⁷Cs, and ²⁴¹Am for the soils samples were measured as 1650, 7100, and 6800聽Bq聽kg^鈭? (d.w.), respectively. The deposit of ¹³⁷Cs for the top 20聽cm of soil on the tested plots at the 鈥淭aiga鈥?site ranged from 30 to 1020聽kBq聽m^鈭?; the maximal value greatly (by almost 3 orders of magnitude) exceeded the regional background (from global fallout) level of 1.4聽kBq聽m^鈭?. ¹³⁷Cs contributes approximately 57%of the total ground inventory of the man-made 纬-ray emitters for the six plots tested at the 鈥淭aiga鈥?site. The other major radionuclides - ²⁴¹Am and ⁶⁰Co, constitute around 40%. Such radionuclides as ⁶⁰Co, ¹³⁷Cs, ²⁴¹Am, and ²⁰⁷Bi have also been determined for the epigeic lichens (genera Cladonia) that colonized certain areas at the ground lip produced by the 鈥淭aiga鈥?explosion. Maximal activity concentrations (up to 80聽Bq聽kg^鈭? for ⁶⁰Co, 580聽Bq聽kg^鈭? for ¹³⁷Cs, 200聽Bq聽kg^鈭? for ²⁴¹Am, and 5聽Bq聽kg^鈭? for ²⁰⁷Bi; all are given in terms of d.w.) have been detected for the lower dead section of the organisms. The air kerma rates associated with the anthropogenic sources of gamma radiation have been calculated using the data obtained from the laboratory analysis. For the six plots tested, the kerma rates ranged from 50 to 1200聽nGy聽h^鈭?; on average, 51%of the dose can be attributed to ¹³⁷Cs and 45%to ⁶⁰Co. These estimates agree reasonably well with the results of the in situ measurements made during our field survey of the 鈥淭aiga鈥?site in August 2009.