Noble gas diffusion through variably-saturated rock: implications for verification of subsurface nuclear events
Date:
Los Alamos, NM
Poster at LANL Student Symposium
Los Alamos National Laboratory
Abstract:
Gas transport through variably-saturated geologic media has important applications for nuclear nonproliferation, as noble gas detection is one of the best candidates for the verification of clandestine underground nuclear events. The transport properties of porous geologic media with respect to such gases are of fundamental importance in developing accurate predictive transport models to determine the origin of detected nuclear signatures. We therefore aim to characterize the diffusion of gaseous krypton, xenon, and sulfur hexafluoride (SF6) through intact porous rock with varying degrees of liquid saturation in order to quantify vapor diffusion coefficients and relate them to changes in rock saturation. We conducted a series of diffusion cell experiments using intact tuff cores at varying saturations. We fit the experimental results using Finite Element Heat and Mass (FEHM) numerical model simulations to calculate effective vapor phase diffusion coefficients for each gas and saturation. Results will be used to develop more accurate transport models for subsurface fission product releases, which have implications for treaty verification, repository science, and radioactive contaminant transport.