Preliminary identification of potentially disruptive scenarios at the Greater Confinement Disposal Facility, Area 5 of the Nevada Test Site

摘要

The Greater Confinement Disposal location is being evaluated to determine whether defense-generated transuranic waste buried at this location complies with the Containment Requirements established by the US Environmental Protection Agency. One step in determining compliance is to identify those combinations of events and processes (scenarios) that define possible future states of the disposal system for which performance assessments must be performed. An established scenario-development procedure was used to identify a comprehensive set of mutually exclusive scenarios. To assure completeness, 761 features, events, processes, and other listings (FEPS) were compiled from 11 references. This number was reduced to 205 primarily through the elimination of duplications. The 205 FEPs were screened based on site-specific, goal-specific, and regulatory criteria. Four events survived screening and were used in preliminary scenario development: (1) exploratory drilling penetrates a GCD borehole, (2) drilling of a withdrawal/injection well penetrates a GCD borehole, (3) subsidence occurs at the RWMS, and (4) irrigation occurs at the RWMS. A logic diagram was used to develop 16 scenarios from the four events. No screening of these scenarios was attempted at this time. Additional screening of the currently retained events and processes will be based on additional data and information from site-characterization activities. When screening of the events and processes is completed, a final set of scenarios will be developed and screened based on consequence and probability of occurrence.