Verification of the plant dynamics analytical code CERES. Comparison with the SAS4/SASSYS-1 code based on the analysis of the small fast reactor

The CERES was validated by the comparison of code to code with a plant dynamics analysis code SAS4A/SASSYS-1. SAS4A/SASSYS-1 is developed by Argonne National Laboratory (USA), and, it has been verified by the FFTF/EBR-II analysis results. The loss-of-offsite-power event (TBO) and the unprotected-loss-of-flow event (ULOF) of 4S reactor (August 2006 design) were analyzed by both codes. The main results as follows; (1) Almost same values were predicted for the reactor core inlet/outlet temperature, the peak temperature occurrence timing, the IHX temperature, and the secondary system temperatures in the ULOF event analysis. (2) The IHX primary inlet temperature predicted by CERES lie between the SAS4A/SASSYS-1 results both with and without thermal stratification model in the TOB event that the low temperature sodium flows out to the upper plenum. From the result, the rationality of the plenum model of CERES was confirmed. Therefore, the fundamental abilities of the CERES to analyze natural circulation and the core reactivity feedback were able to be confirmed. (author)