The Waste Isolation Pilot Plant (WIPP) is under development by the U.S. Department of Energy (DOE) for the geologic disposal of transuranic waste. The construction of complementary cumulative distribution fimctions (CCDFS) for total radionuclide release from the WIPP to the accessible environment is described. The resultant CCDFS (i) combine releases due to cuttings~d cavings, spallings, direct brine release, and long-term transportin flowing groundwater, (ii) fall substantially to the left of the boundary line specified by the U.S. Environmental Protection Agency's (EPA's) standard40 CFR 191 for the geologic disposal of radioactive waste, and (iii) constitute an important component of the DOE's successfid Compliance Certification Application to the EPA for %.heWIPP.Insights and perspectives gained in the performance assessment (PA) that led to these CCDFS are described, including the importance of (i) an iterative approach to PA, (ii) uncertainty and sensitivity analysis, (iii) a clear conceptual model for the analysis, (iv) the separation of stochastic (i.e., aleatory) and subjective (i.e., epistemic) uncertainty,(v) quality assuranceprocedures, (vi) early involvement of peer reviewers, regulators, and stakeholders, (vii) avoidance of conservative assumptions, and (viii) adequate documentation.