The purpose of this methods report is to document: (1) the origin, and the methods used in the development of a comprehensive list of features, events, and/or processes (FEPs) that could potentially affect the postclosure performance of the Yucca Mountain disposal system; (2) the methodology and guidance used to screen FEPs for inclusion or exclusion from Total System Performance Assessment for the License Application (TSPA-LA) analysis; (3) the methodology and guidance used to create scenario classes; and (4) compliance with NUREG-1804 (NRC 2003.

The purpose of this analysis report is to document the screening decisions and technical bases for inclusion or exclusion of each FEP identified as relevant to the TSPA and the Yucca Mountain disposal system, in accordance with the regulatory screening criteria identified for the Yucca Mountain Site.

This analysis documents the screening analysis for postclosure criticality features, events, and
processes (FEPs). It addresses the probability of criticality events resulting from degradation
processes as well as disruptive events (i.e., seismic, igneous, and rockfall). Probability
evaluations are performed utilizing the configuration generator model described in Configuration
Generator Model for In-Package Criticality1, a component of the methodology from Disposal