The purposes of this analysis are: (1) Categorize (as Category 1, Category 2, or Beyond Category 2) internal event sequences that may occur before permanent closure of the repository at Yucca Mountain. (2) Categorize external event sequences that may occur before permanent closure of the repository at Yucca Mountain. This includes examining DBGM-1 seismic classifications and upgrading to DBGM-2, if appropriate, to ensure Beyond Category 2 categorization. (3) State the design and operational requirements that are invoked to make the categorization assignments valid. (4) Indicate the amount of material put at risk by Category 1 and Category 2 event sequences. (5) Estimate frequencies of Category 1 event sequences at the maximum capacity and receipt rate of the repository. (6) Distinguish occurrences associated with normal operations from event sequences. It is beyond the scope of the analysis to propose design requirements that may be required to control radiological exposure associated with normal operations. (7) Provide a convenient compilation of the results of the analysis in tabular form. The results of this analysis are used as inputs to the consequence analyses in an iterative design process that is depicted in Figure 1. Categorization of event sequences for permanent retrieval of waste from the repository is beyond the scope of this analysis. Cleanup activities that take place after an event sequence and other responses to abnormal events are also beyond the scope of the analysis.