USE OF PERFORMANCE ASSESSMENT INFORMATION TO EVALUATE ALTERNATIVE YUCCA MOUNTAIN PERFORMANCE STANDARDS By:

The continuing advance of scientific knowledge and the evolution of performance assessment capabilities for the proposed spent fuel and HLW repository at Yucca Mountain have resulted in the means to evaluate the appropriateness of Yucca Mountain performance regulations. This paper provides some examples of how performance assessment information has been used to evaluate Yucca Mountain regulations as well as a description of how regulatory thinking has been influenced by these performance assessments. BACKGROUND Regulations governing the performance of geologic repositories for the disposal of spent fuel and HLW in the US have evolved for more than 20 years. Regulations governing site selection and radiological health and safety were developed by both the US Nuclear Regulatory Commission (NRC) and the US Environmental Protection Agency (EPA). The technical criteria in NRC’s 10 CFR Part 60 were first promulgated in 1983 (1). Part 60 contains a series of prescriptive, quantitative criteria on a variety of components of a geologic repository system. For example, NRC provided quantitative limits on: minimum groundwater travel time from the engineere