Modeling Gas and Brine Migration for Assessing Compliance of the WIPP

Vaughn, P.; Butcher, B.; Helton, J.; Swift, P.; ,

Modeling Gas and Brine Migration for Assessing Compliance of the WIPP

by P. Vaughn, Sandia Natl Lab, Albuquerque, United States,
B. Butcher, Sandia Natl Lab, Albuquerque, United States,
J. Helton, Sandia Natl Lab, Albuquerque, United States,
P. Swift, Sandia Natl Lab, Albuquerque, United States,

Document Type: Proceeding Paper

Part of: High Level Radioactive Waste Management 1993

Abstract:

The U.S. Department of Energy (DOE) is developing the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico as a facility for the long-term disposal of defense-related transuranic (TRU) wastes. Use of the WIPP for waste disposal is contingent on demonstrations of compliance with applicable regulations of the U.S. Environmental Protection Agency (EPA). This paper addresses issues related to modeling gas and brine migration at the WIPP for compliance with both EPA 40 CFR 191 (the Standard) and 40 CFR 268.6 (the RCRA). At the request of the WIPP Project Integration Office (WPIO) of the DOE, the WIPP Performance Assessment (PA) Department of Sandia National Laboratories (SNL) has completed preliminary uncertainty and sensitivity analyses of gas and brine migration away from the undisturbed repository. This paper contains descriptions of the numerical model and simulations, including model geometries and parameter values, and a summary of major conclusions from sensitivity analyses. Because significant transport of contaminants can only occur in a fluid (gas or brine) medium, two-phase flow modeling can provide an estimate of the distance to which contaminants can migrate. Migration of gas or brine beyond the RCRA 'disposal-unit boundary' or the Standard's accessible environment constitutes a potential, but not certain, violation and may require additional evaluations of contaminant concentrations.

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