Representation of two-phase flow in the vicinity of the repository in the 1996 performance assessment for the Waste Isolation Pilot Plant

The following ropics related to the representation of two-phase (i.e. , gas and brine) flow in the licinity of the reposito~ in the 1996 performance assessment (P.4) for the Y$’aste Isolation Pilot Plant (IVIPP) are discussed: (i) system of nordin-partial differential equations used to model two-phase flow, (ii) incorporation of repository . shafis imo model (iii) creep closure of repository. (iv) interbed fracturing, (v) gas generatio~ (vi) capillary action in waste, (~ii) borebole rnode~ (~lii) numtical SOhItjOn. and (k) gas rind btie flow across ~ecified boundaries. Twophase flow calculations are a cereal part of the 1996 WIPP P.4 and supply results that are subsequently used in the calculation of releases to the surface at the time of a drilling intrusion (i.e., spalIings, direct brine releases) and longterm releases due to radionucIide transport by flowing groundwater.