[en] This document presents a series of six case study analyses of groundwater flow and contaminant transport in the subsurface formations underlying the Rainier Mesa (RM) testing area at the NNSS. The analyses are designed to assess the potential over a 1,000-year period for radionuclide contamination derived from underground nuclear tests at RM to enter and migrate in saturated groundwater underlying the testing areas. The radionuclide source zones at RM consist of individual test centers corresponding to 62 unique detonations conducted in 2 shafts and 11 tunnel complexes; the E-, N-, and T-Tunnel pond systems that captured contaminated water discharged from these tunnel complexes (and continue to do so in the case of E-Tunnel); and the contaminated N- and T-Tunnel “reservoirs” that formed behind plugs installed between 1992 and 1994 to block subsequent contaminant losses into the N- and T-Tunnel ponds.