Analysis of a PSB-VVER small break LOCA experiment with APROS and TRACE system codes

Best-estimate thermal–hydraulic system codes are widely used for the analysis of various postulated events of NPPs, therefore, an extensive verification and validation of these codes is essential. In the current study, an SB-LOCA scenario (CL-4.1-03) of the PSB-VVER integral test facility has been investigated using NRC's novel system code, TRACE, and the Finnish APROS, which had already been in long use at our Institution. PSB-VVER is currently the most comprehensive physical model of the VVER-type reactors, particularly VVER-1000, in most of the aspects. The experiment under study was carried out in 2004 in the framework of an OECD NEA benchmark. The obtained results have been compared to the benchmark and to each other both from a qualitative and quantitative point of view. As a figure of merit, the improved FFTBM-SM and the SARBM quantitative methods were used. Furthermore, the main lessons learnt during the model development are also presented.