Xenon adsorption on geological media and implications for radionuclide signatures. (July 2018)

• Record Type: Journal Article
• Authors: Paul, M.J.; Biegalski, S.R.; Haas, D.A.; Jiang, H.; Daigle, H.; Lowrey, J.D.
• Is Part Of: Journal of environmental radioactivity. Volume 187(2018)
• Page Start: 65
• Page End: 72
• Publication Date: 2018-07
• Subjects: Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2018.01.029
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: 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. Highlights: Physical adsorption of xenon results in non-trivial retardation factors. In a dual-porosity system, the xenon will diffuse from fractures into the matrix. Diffusion into an adsorbent matrix is amplified during transient accumulation. Reactive losses are similarly amplified in an adsorbent matrix. Radioxenon signatures have between a root and linear dependence on retardation.