The purpose of this report is to <,locument the sensitivity of the drift-scale thermal-hydrologic- chemical (THC) seepage model (SNL 2007 [DIRS 177404]) to heterogeneities in permeability and capillarity, which could affect predicted fluxes and chemistries of water and gases seeping into the emplacement drifts. This report has been developed following Technical Work Plan for: Revision of Model Reports for Near-Field and In-Drift Water Chemistry (SNL 2007 [DIRS 179287]).

The purpose of this report is to document the thermal-hydrologic-chemical (THC) seepage model and model simulations. The simulations predict the composition of fracture water that could potentially seep into repository emplacement drifts and the composition of the associated gas phase. The THC seepage model is not used to feed the total system performance assessment (TSPA) for the license application (LA).