Paul M J, Biegalski S R, Haas D A, Jiang H, Daigle H, Lowrey J D
Nuclear Engineering Teaching Laboratory, The University of Texas at Austin, 10100 Burnet Rd, Bldg 159, Austin, TX 78758, USA.
Nuclear Engineering Teaching Laboratory, The University of Texas at Austin, 10100 Burnet Rd, Bldg 159, Austin, TX 78758, USA.
J Environ Radioact. 2018 Jul;187:65-72. doi: 10.1016/j.jenvrad.2018.01.029. Epub 2018 Feb 13.
The detection of radioactive noble gases is a primary technology for verifying compliance with the pending Comprehensive Nuclear-Test-Ban Treaty. A fundamental challenge in applying this technology for detecting underground nuclear explosions is estimating the timing and magnitude of the radionuclide signatures. While the primary mechanism for transport is advective transport, either through barometric pumping or thermally driven advection, diffusive transport in the surrounding matrix also plays a secondary role. From the study of primordial noble gas signatures, it is known that xenon has a strong physical adsorption affinity in shale formations. Given the unselective nature of physical adsorption, isotherm measurements reported here show that non-trivial amounts of xenon adsorb on a variety of media, in addition to shale. A dual-porosity model is then discussed demonstrating that sorption amplifies the diffusive uptake of an adsorbing matrix from a fracture. This effect may reduce the radioxenon signature down to approximately one-tenth, similar to primordial xenon isotopic signatures.
放射性惰性气体的检测是核查是否遵守即将生效的《全面禁止核试验条约》的一项主要技术。将该技术应用于探测地下核爆炸的一个根本挑战是估算放射性核素特征的时间和强度。虽然传输的主要机制是平流传输，要么通过气压抽吸，要么通过热驱动平流，但周围介质中的扩散传输也起次要作用。从对原始惰性气体特征的研究可知，氙在页岩地层中具有很强的物理吸附亲和力。鉴于物理吸附的非选择性，此处报道的等温线测量结果表明，除了页岩之外，大量的氙还吸附在各种介质上。然后讨论了一个双孔隙度模型，该模型表明吸附作用会放大吸附性基质从裂缝中的扩散吸收。这种效应可能会使放射性氙特征降低到大约十分之一，类似于原始氙同位素特征。
