Methods and Techniques Used to Convey Total System Performance Assessment Analyses and Results for Site Recommendation at Yucca Mountain, Nevada, USA

Total System Performance Assessment (TSPA) is used as a key decision-making tool for the potential geologic repository for high level radioactive waste at Yucca Mountain, Nevada, USA. Because of the complexity and uncertainty involved in a post-closure performance assessment, an important goal is to produce a transparent document describing the assumptions, the intermediate steps, the results, and the conclusions of the analyses. An important objective for a TSPA analysis is to illustrate confidence in performance projections of the potential repository given a complex system of interconnected process models, data, and abstractions. The methods and techniques used for the recent TSPA analyses demonstrate an effective process to portray complex models and results with transparency and credibility.