Carbol P, Solatie D, Erdmann N, Nylén T, Betti M
European Commission, Joint Research Centre, Institute for Transuranium Elements, PO Box 2340, D-76125 Karlsruhe, Germany.
J Environ Radioact. 2003;68(1):27-46. doi: 10.1016/S0265-931X(03)00027-4.
In this article the distribution of fission products and actinides in a soil profile from Novo Bobovicky in Russia, which was contaminated due to the Chernobyl nuclear power plant accident, is described. The ground deposition of long-lived fission products determined by gamma-spectrometry was (recalculated to 26 April 1986) 1600 kBq (137)Cs/m(2), 900 kBq (134)Cs/m(2) and 60 kBq (125)Sb/m(2). Of these radionuclides (137)Cs shows the dominating activity at the present time. After 6.5 years 90% of the Cs and Sb activity was contained in the upper 4 cm. A (239,240)Pu ground deposition of 77.4+/-8.0 Bq/m(2) was determined by alpha-spectrometry. The (238)Pu/(239,240)Pu activity ratio of 0.30+/-0.03 and (241)Pu/(239,240)Pu activity ratio of 115+/-14 (in 1986) measured in the soil profile, indicates that the analysed Pu originates mainly from the Chernobyl accident. The average (234)U/(238)U activity ratio of 1.06+/-0.29 indicates that the uranium in this soil is dominated by naturally occurring uranium. The alpha- and beta-autoradiography revealed that the activity is mainly present in particulate form. It could further be observed that the spots containing alpha- or beta-activity originated from different particles. A comparison of alpha-autoradiography with the bulk Pu and Am activity showed that 92% of the alpha-activity was present as clearly detectable alpha-spots. The beta-active particles, located by beta-autoradiography were correlated with gamma-spectrometric measurements and contained only (137)Cs. These hot spots ranged from 0.02 to 0.15 Bq.It could be concluded that the vertical transport of (137)Cs and fuel fragments occurs mainly by movement of particles through the soil. It could also be concluded that the fuel fragments found, in this soil were depleted in respect to Cs, Sb and Eu. Comparison of the analysed (238)Pu/(239,240)Pu, (241)Pu/(239,240)Pu and (241)Am/(239,240)Pu ratios with the ratios calculated with ORIGEN-S code gave an estimate of the average burn-up of the fuel particles to be in the range of 11-12 GWd/tU. The results presented in this article are valid for this single soil profile and should not be generalised unless validated in a more rigorous study of a larger number of soil profiles.
本文描述了俄罗斯新博博维茨基一处因切尔诺贝利核电站事故而受污染的土壤剖面中裂变产物和锕系元素的分布情况。通过伽马能谱法测定的长寿命裂变产物地面沉积量（重新计算至1986年4月26日）为：1600 kBq（137）铯/平方米、900 kBq（134）铯/平方米和60 kBq（125）锑/平方米。在这些放射性核素中，目前（137）铯的活度占主导。6.5年后，90%的铯和锑活度集中在上层4厘米处。通过阿尔法能谱法测定的（239,240）钚地面沉积量为77.4±8.0 Bq/平方米。在土壤剖面中测得的（238）钚/（239,240）钚活度比为0.30±0.03，（241）钚/（239,240）钚活度比为115±14（1986年），这表明所分析的钚主要源自切尔诺贝利事故。平均（234）铀/（238）铀活度比为1.06±0.29，表明该土壤中的铀主要是天然铀。阿尔法和贝塔放射自显影显示，活度主要以颗粒形式存在。还可进一步观察到，含有阿尔法或贝塔活度的斑点源自不同颗粒。阿尔法放射自显影与总钚和镅活度的比较表明，92%的阿尔法活度以清晰可检测的阿尔法斑点形式存在。通过贝塔放射自显影定位的贝塔活性颗粒与伽马能谱测量相关，且仅含有（137）铯。这些热点范围为0.02至0.15 Bq。可以得出结论，（137）铯和燃料碎片的垂直迁移主要是通过颗粒在土壤中的移动实现的。还可以得出结论，在该土壤中发现的燃料碎片在铯、锑和铕方面有所贫化。将分析得到的（238）钚/（239,240）钚、（241）钚/（239,240）钚和（241）镅/（239,240）钚比值与用ORIGEN - S代码计算的比值进行比较，得出燃料颗粒的平均燃耗估计在11 - 12 GWd/tU范围内。本文给出的结果仅适用于该单一土壤剖面，除非在对更多土壤剖面进行更严格研究后得到验证，否则不应进行推广。
