Experience in KINS on Best Estimate Calculation with Uncertainty Evaluation

In the present paper, experience of Korea Institute of Nuclear Safety (KINS) on Best Estimate (BE) calculation and uncertainty evaluation of large break loss-of-coolant accident (LB LOCA) of Korean Pressurized Water Reactor (PWR) with various type of Emergency Core Cooling System (ECCS) design is addressed. Specifically, the current status of BE code, BE calculations and uncertainty parameters and related approaches are discussed. And the specific problem such as how to recover the difficulty in treating the uncertainty related to the phenomena specific to ECCS design (e.g., upper plenum injection phenomena) is discussed. Based on the results and discussion, it is found that the present KINS-REM has been successfully developed and applied to the regulatory auditing calculations. Need of further study includes the improvement of reflood model of MARS code, uncertainty of blowdown quenching, and reconsideration of the unconcerned model and fuel conductivity degradation with burnup. (authors)