CEA, DEN/DANS/DPC , Laboratory of Radionuclides Migration Measurements and Modeling, bât 450, F-91191 Gif-sur-Yvette, France.
Environ Sci Technol. 2012 Mar 6;46(5):2633-41. doi: 10.1021/es2037433. Epub 2012 Feb 22.
The diffusion of cesium was studied in an unsaturated core of Callovo-Oxfordian claystone, which is a potential host rock for retrievable disposal of high-level radioactive wastes. In-diffusion laboratory experiments were performed on rock samples with water saturation degrees ranging from 81% to 100%. The analysis of both cesium concentration monitoring in the source reservoir and post-mortem cesium rock concentration profile of the samples was carried out using a chemical-transport code where the sorption of cesium was described by a multisite ion-exchange model. The results showed that cesium exhibited a clear trend related to the saturation degree of the sample. The more dehydrated the rock sample, the slower the decrease of cesium concentration, and the thinner the penetration depth of cesium was. The effective diffusion coefficient (De) for cesium decreased from 18.5 × 10(-11) m(2) s(-1) at full-saturation to 0.3 × 10(-11) m(2) s(-1) for the more dehydrated sample. This decrease is almost 1 order of magnitude higher than that for tritiated water (HTO), although a similar behavior could have been expected, since cesium is known to diffuse in the same parts of the pore space as HTO in fully saturated claystones.
研究了铯在可能用于高放废物可回取处置的索利卡姆斯克粘土岩非饱和岩芯中的扩散行为。对水饱和度分别为 81%到 100%的岩芯样品进行了内扩散实验室实验。使用化学输运代码分析了源储中铯浓度的监测以及样品的死后铯浓度剖面，其中用多位置离子交换模型描述了铯的吸附。结果表明，铯的浓度变化与样品的饱和度存在明显的关系。岩芯越干燥，铯浓度下降越慢，铯的穿透深度越浅。对于更干燥的样品，铯的有效扩散系数（De）从完全饱和时的 18.5×10(-11)m(2)s(-1)降低到 0.3×10(-11)m(2)s(-1)。这种降低几乎比氚水（HTO）高 1 个数量级，尽管可以预期铯的行为与 HTO 相似，因为已知铯在完全饱和的粘土岩中与 HTO 在相同的孔隙空间中扩散。
