Performance assessment for the Waste Isolation Pilot Plant: From regulation to calculation for 40 CFR 191.13

The Waste Isolation Pilot Plant (WIPP) is being developed by the U.S. Department of Energy as a disposal facility for transuranic waste and must comply with several environmental regulations, including the U.S. Environmental Protection Agency's standard for geologic disposal of radioactive waste (40 CFR 191). Procedures used in recent performance assessments for the WIPP to translate regulations into a structure that facilitates quantitative analysis we described. Topics considered include (I) development of a clear conceptual representation for problems that are initially ill-defined, (2) conversion of qualitative guidance into numerical calculations, (3) explicit incorporation of different types of uncertainty (i.e., aleatory and epistemic) into analysis outcomes, (4) requirements for efficient computation and models at different levels of complexity, (5) use of sensitivity analysis to guide additional data collection and future calculations, (6) requirements for results to be presented and explained to audiences with different interests and levels of sophistication, and (7) ambiguity with respect to final uses of the analysis and its outcomes. The need to address similar concepts and problems arises in many analyses.