PRELIMINARY DEVELOPMENT OF A SEISMIC PRA MODEL USING FRANX/CAFTA/ACUBE/UNCERT

摘要

In the wake of the Fukushima Daiichi accident, the US NRC will require seismic probabilistic risk assessments (SPRAs) for selected US commercial nuclear power plants. As such, new techniques and tools are being developed to meet this demand. To explore the capabilities of these tools, Scientech is developing a demonstration SPRA using preliminary data for its Fermi Unit 2 SPRA project. The demo analysis focuses on tools in the Electric Power Research Institute's (EPRI's) suite of programs, namely FRANX, CAFTA, ACUBE and UNCERT. Specifically, the newly developed seismic analysis add-on for FRANX is being used in conjunction with existing CAFTA programs to create and quantify a top logic model that will be further analyzed by ACUBE and UNCERT. A focus was placed on the ability to use these programs to create the seismic model in such a way that minimal effort is required to transition into the final SPRA model. This paper describes how a number of FRANX and CAFTA features facilitate this ability. Due to the preliminary nature of this project, the hazard curve and fragility information initially were approximated. The hazard curve was later replaced with the 100 Hz fractile curves that will be used in the SPRA. Because representative generic fragilities were developed for the top risk significant components in the IEPRA model and other modifications are of a preliminary nature, however, the results are presented as a description of the techniques used and a comparison of quantification results between techniques.