Investigating incorporation and distribution of radionuclides in trinitite
Investigating incorporation and distribution of radionuclides in trinitite
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DOI：
10.1016/j.jenvrad.2011.05.003
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发表时间：
2011-09-01
影响因子：
2.3
通讯作者：
Romanello, V.
中科院分区：
文献类型：
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作者：
Belloni, F.;Himbert, J.;Romanello, V.
核试验中的大多数地面爆炸都以大块玻璃状物质的形式向环境释放放射性，这些物质来自爆点附近沙土的融化。为了澄清有关这些物质的形成机制和放射性影响的问题，我们研究了放射性核素在三位一体典型碎片中的掺入和体积分布，三位一体是第一次核试验（新墨西哥州三位一体试验场，1945年）后产生的玻璃状物质。用伽马能谱法测定了最显著的裂变和活化产物的比活度。特别是，（152）欧盟活动被用来估计样品的原始收集点相对于地面零点。在环氧树脂中包埋后，将样品切片进行横切面β -和α -自射线照相。用α -光谱法测定了经表面研磨得到的细粉。在β射线自显影中，在靠近爆炸侧的地方可以区分出热点，超过1000倍的砂活化产物的强烈背景。此外，a污染（来自（239+240）Pu和（241）Am）主要集中在表层，仅占样品总体积的20%，呈不连续的液滴状分布。这一证据将部分支持最近关于三原岩形成的假设，根据该假设，大部分玻璃层不是在地面上形成的，而是由注入火球的物质雨形成的，这些物质融化，回落，并聚集在已经熔化的沙子床上。爱思唯尔有限公司版权所有版权所有。
Most of the surface explosions in nuclear tests have released radioactivity to the environment in the form of bulk glassy materials originating from the melting of sandy soil in the neighbourhood of ground zero. In view of clarifying issues concerning the mechanism of formation and the radiological impact of these materials, we investigated incorporation and volume distribution of radionuclides in a typical fragment of trinitite, the glassy substance generated following the first nuclear test (Trinity Site, New Mexico, 1945). Specific activities were determined by gamma-spectrometry for the most significant fission and activation products. In particular, (152)Eu activity was used to estimate the original point of collection of the sample with respect to ground zero. After embedding in an epoxy resin, the sample was then sliced to perform cross-sectional beta- and alpha-autoradiograph. alpha-spectrometry was also carried out on a fine powder obtained by surface abrasion. In the beta-autoradiography, hot spots were distinguishable in the proximity of the blast side, over a 1000 times less intense background of sand activation products. Also a-contamination (from (239+240)Pu and (241)Am) was mostly concentrated within the superficial layer, in a fraction of only 20% of the overall volume of the sample, exhibiting a discontinuous, droplet-like distribution. This evidence would partially support a recent hypothesis on trinitite formation according to which most of the glass layer was formed not on the ground but by a rain of material injected into the fireball that melted, fell back, and collected on a bed of already fused sand. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.