Demonstration of the E-BEPU Methodology for LB-LOCA in NPP with PWR Reactor

The paper presents preliminary results for the application of the new Extended Best Estimate Plus Uncertainty (E-BEPU) methodology developed in the framework of the Horizon-2020 NARSIS project. The approach is risk-informed combined deterministic and probabilistic methodology dedicated to Nuclear Power Plant (NPP) systematic design verification and to enhance Defence-in-Depth (DiD). It assumes application of the best-estimate computer code, realistic input data for initial and boundary conditions and plant systems availability based on Probabilistic Safety Analysis (PSA). It extends the scope of the uncertainty analysis to include the availability of safety systems as an additional uncertain item. The generic large Generation III Pressurized Water Reactor (PWR) design with core thermal power of 4500 MW defined in the NARSIS project was applied. The surge line LB-LOCA, a postulated initiating event, was studied as an example of design basis type event. This study is the first practical application of the E-BEPU methodology, which is under development in the NARSIS Project.