Analysis of void fraction in single channel using TRACE, MARS-KS, and RELAP5

The accurate prediction of the void fraction is one of the most important factors in subchannel analyses. In general, the subchannel analysis has been conducted by means of dedicated subchannel analysis codes. However, the recent development of system codes with advanced two-phase flow model and three-dimensional components has helped more accurate and precise prediction of multiphase phenomena in nuclear reactor systems. This paper aims at evaluating the applicability of three different system codes to the prediction of the void fraction based on NUPEC experiment results employed for OECD/NRC PSBT benchmark. As a first step to the full scope analysis, analysis results for single channel experiments by using TRACE 5.0 Patch 3, MARS-KS 1.3, and RELAP5/MOD3.3 Patch 4 are presented in this paper. The result indicates that all codes slightly over-predict the void fraction compared to the experimental results in general and no significant discrepancies between the codes are observed. (author)