EVALUATION OF THALES SUBCHANNEL CODE BEHAVIOR FOR LOSS OF FLOW AND RCP ROTOR SEIZURE SCENARIOS

摘要

KEPCO Nuclear Fuel (KNF) recently developed a new subchannel analysis code called THALES (Thermal Hydraulic AnaLyzer for Enhanced Simulation of core). To benchmark the code independently, its performance and characteristics are examined by simulating loss of flow and RCP rotor seizure scenarios of Shinkori 3&4. The core inlet and outlet conditions are taken from Shinkori 3&4 design with PLUS7 fuel. VIPRE-01 code is used for comparison. VIPRE-01 code was developed by EPRI and has been used widely. The above transients were simulated with the same correlation options. For the comparison between the codes, we chose CE-1 CHF correlation, which are available in both codes. CE-1 correlation was developed for CE type fuel. The comparison shows that the code predictions are close. The key parameter is minimum departure from nucleate boiling ratio (MDNBR). The maximum difference in MDNBR is less than 3%. The axial location of MDNBR is very close though the channel exhibiting MDNBR is different. However, the channel is located symmetrically and the radial power values of the channel are the same. Then, THALES code is used to examine PLUS7 fuel performance with KCE-1 CHF correlation which is developed for PLUS7 fuel. The effect of using KCE-1 correlation improves MDNBR showing the effect of improved fuel performance. Lastly, the effect of axial power shape is examined. Several different axial power shapes are examined to identify the most limiting shape, which is one of top-skewed profile.