DWPF Mode C probablistic safety analysis

This report documents the probabilistic safety analysis (PSA) developed for Mode C operation of the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS). The DWPF Mode C PSA is a bounding accident analysis with a primary objective of quantifying the maximum credible radiological source terms and consequences associated with the significant accident types identified during the facility hazard evaluation. A detailed discussion of the methodologies used and the results obtained is presented. The final output of the DWPF Mode C PSA is a set of bounding credible scenarios that conservatively encompass all of the credible accident progression sequences postulated to occur in the DWPF. For each bounding credible scenario, radiological consequences, source terms, and an associated frequency of occurrence are presented. Comparisons to the applicable acceptance criteria demonstrate that the radiological risks posed to offsite and co-located receptors due to these scenarios are well below the acceptance criteria, and are therefore acceptable. The results further demonstrate that there are no events lying just below the design basis credibility threshold that possess unacceptable consequences, or consequences that are markedly higher than those for the bounding credible scenarios. These results define the safety envelope for Mode C operation of the DWPF, and verify the sufficiency of the safety features and systems employed to protect the facility