Overpressure Protection Analysis Methodology with RAMONA-3B

Abstract

The purpose of this paper is to present a methodology proposed to perform the analysis of the most severe pressurization transient in a BWR system with the RAMONA-3B code. The results of the analysis are compared against the Final Safety Analysis Report (FSAR) of the Laguna Verde Nuclear Power Plant (CLV). Comparisons of data from pressurization events recorded at the plant and simulated with RAMONA-3B with conservative results are also presented. The objective of the analysis is to determine the maximum pressure peak reached in the vessel bottom and to show compliance with the ASME Boiler and Pressure Vessel Code. The evaluation of several pressure increase transients has shown that the isolation valve closure is the most severe event when credit is taken only for indirect derived scrams, therefore, it is used as the overpressure protection basis event. The reactor protection system via high flux scram acts to shut down the reactor avoiding serious damages to the nuclear system.