COMMENTS ON AN EVALUATION OF THE 1992 PERFORMANCE ASSESSMENT FOR THE WASTE-ISOLATION-PILOT-PLANT

The following topics are discussed in a review of the 1992 performance assessment (PA) for the Waste Isolation Pilot Plant (WIPP): (1) inclu sion of potash mining and other disruptions in the definition of possi ble futures at the WIPP, (2) definition of future drilling rates in th e vicinity of the WIPP, (3) possible non-conservatisms in analysis ass umptions, (4) characterization of uncertainty in solubilities, and (5) characterization of uncertainty in distribution coefficients. With re spect to (1) and (2), the 1992 WIPP PA attempted to follow guidance in the US Environmental Protection Agency's (EPA's) standard for the geo logical disposal of radioactive waste, 40 CFR 191. Many of the reviewe r's comments relate to the EPA's recent guidance in 40 CFR 194 on asse ssing compliance with 40 CFR 191, which was not published until early 1996 and which makes many changes from the guidance given in 40 CFR 19 1. The 1996 WIPP PA, which will support a compliance certification app lication to the EPA, will follow the guidance in 40 CFR 194. With resp ect to (3), (4) and (5), the WIPP PA tries to avoid both deliberate co nservatism and deliberate non-conservatism. The 1992 WIPP PA attempted to use all the information available to it consistent with the requir ements to incorporate uncertainty in PA results and to use 'reasonable expectation' as the criterion for assessing compliance with 40 CFR 19 1. Since 1992, many additional results related to solubilities and dis tribution coefficients have become available. The 1996 WIPP PA will in corporate these new results. (C) 1997 Elsevier Science S.A.