Post-Test-Analysis and Nodalization Studies of OECD LOFT Experiment LP-02-6 with RELAP5/MOD2 CY36-02, August 1992. International Agreement Report

摘要

The report presents the results and analysis of nine post-test calculations of the Experiment LP-02-6 by using RELAP5/MOD2 CY36-02 computer code with different nodalizations. Starting with a 'standard nodalization' the authors have reduced the number of volumes and junctions as well as the number of radial zones in the fuel rods, for different nodalization studies. Except for the cladding temperatures, only small discrepancies have been observed for the other main parameters of the results of runs using different nodalizations but reduced number of volumes and junctions usually have lead to a decreased running time for the problem. The time behaviors of the cladding temperatures have been significantly affected by the chosen nodalizations. The most comparable results with the experimental data have been achieved by using medium number of nodes. With respect to high mass-flux, early bottom-up rewetting, one of the key-events of Experiment LP-02-6 as well as of most of the other LOFT large break experiments, RELAP5/MOD2 was not able to predict the phenomenon except with a certain manipulation by initiating the reflood option.