Development of Containment Failure Probability and Uncertainty Analysis Program, COFUN-M

Abstract

The feature of the COFUN-M is quantification of the containment state by point estimate value, importance analysis, sensitivity analysis and uncertainty analysis for internal and seismic event. The uncertainty analysis process of the level 2 PSA is that a level 1 PSA uncertainty propagate to a level 2 PSA uncertainty. In order to perform uncertainty analysis in the COFUN-M code, we need to prepare the input. The basic event probability data including probability distribution were needed and would be used for the level 1 PSA uncertainty analysis. To perform uncertainty analysis in a level 2 PSA, it is necessary to define the split fractional branch point and define the probability distribution and priority. Once the input is ready, uncertainty analysis is performed via Monte Carlo sampling. Finally, the uncertainty analysis is performed for the end point of the PDS, CET, STC and LERF. One of the outstanding characteristics of the COFUN-M is to perform level 2 PSA for multi-unit accident. The one of format of multi-unit level 2 PSA is combination of STCs but the combinations could be too many to acquire insight itself. The COFUN-M provides user-defined combination which makes STC combinations classified.