Analysis on the Direct Vessel Injection Line Break Accident at APR+ Standard Design

APR+ (Advanced Power Reactor +) is the newest design variation of APR1400. The main characteristics of APR+, compared with APR1400, are passive safety systems and dedicated systems for severe accident mitigation. APR+ is under review for standard design certification. In this study, thermal hydraulic analysis on the Direct Vessel Injection (DVI) line break accident postulated in APR+ design was performed. Comparisons of the major parameters which can represent the overall accident behavior during DVI line break accident, several discrepancies between this study and reference data were found and such discrepancies include actuation timing of SIPs and SITs, and also include parameter behaviors of break flow rate and PCT at the accident initiation. These differences were mainly from the different thermal hydraulic models in simulation codes. The behavioral differences for break flow as well as peak cladding temperatures will be examined further as a next step for this study