Main Results of Phase IV BEMUSE Project. Simulation of LBLOCA in a NPP

Phase IV of BEMUSE Program is connected with previous phase II, being a necessary step for an uncertainty analysis: the simulation of the reference scenario and sensitivity analysis. Present phase analyses a LBLOCA scenario in Zion 1 NPP, a 4 loop PWR unit. Thirteen participants coming from ten different countries have taken part in the Phase IV of the program. The BEMUSE (Best Estimate Methods plus Uncertainty and Sensitivity Evaluation) Program has been promoted by the Working Group on Accident Management and Analysis (GAMA) and endorsed by the Committee on the Safety of Nuclear Installations (CSNI). The paper presents the results of the calculations performed by participants and emphasizes its usefulness for future uncertainty evaluation, to be performed in next phase. The objectives of the activity are basically to simulate the LBLOCA reproducing the phenomena associated to the scenario and also to build a common, well-known, basis for the future comparison of uncertainty evaluation results among different methodologies and codes. Following activities performed in phase II, a list of sensitivity calculations was proposed and performed by participants to study the influence of different parameters such as material properties or initial and boundary conditions, upon the behaviour of the most relevant parameters related to the scenario.