Risk assessment methodology for operating a bedded salt repository for unreprocessed spent fuel

This paper summarizes a six-month (approx. 1 man-year) study performed for Sandia National Laboratories (SNL) by General Atomic Company (CA). The purpose of the study was to assemble a methodology to be used in assessing the public health risks associated with the operating phase of a bedded salt repository for disposing of unreprocessed spent nuclear fuel. The basic methodology selected for this purpose was probabilistic risk assessment (PRA). The study focused on a determination of releases of radionuclides (RNs) from the repository to its environe (atmosphere, surface land and waters, subterranean strata, and ground water). The methodology was broad enough to include all anticipated operations, including retrieval. This paper briefly describes the reference repository used as the basis for assembling and exercising the methodology, the types of facility analyses needed for a public health risk assessment, the preliminary screening needed to focus attention in the important areas of analysis, the event and fault trees developed to structure the accident scenarios and to guide the numerical analyses, the frequency and RN release analyses developed from those trees, and the results and conclusions from the study.