Discretization Sensitivity Studies for Dynamic Event Tree Analyses

摘要

The ADAPT (Analysis of Dynamic Accident Progression Trees) software is a tool which can generate dynamic event trees (DETs) using a system simulation tool and a user-specified set of branching rules. The DETs which are generated by ADAPT are a type of discrete DETs. Discrete DETs only branch at specific points in the system state space (i.e., specific times or specific process conditions). Under the ADAPT methodology, the cumulative probability distributions for the failure of passive components or for the occurrence of phenomena (e.g. pipe rupture, containment failure) are discretized and the physical values corresponding to the discrete probability values are used as branching conditions. Whenever discretization of an inherently continuous process is proposed in a methodology, the question of how fine of a discretization is necessary to capture all relevant information must be addressed, particularly for non-linear processes. Exploratory work is being performed to address this issue with the ADAPT methodology. An example case is analyzed using different probability distribution discretization schemes on a set of branching conditions.