Development of safety analysis code for SCWR and its LOCA analysis of CSR1000

In this study, Transient Analysis Code Of SCWR (TACOS), with the ability of simulating transients or accidents under both supercritical water conditions and subcritical water conditions, has been developed. A 3-equation model for supercritical water flow and single phase flow, and a 4-equation drift-flux model for two-phase mixture are adopted. Coupling of the 3-equation model and 4-equation model is utilized to perform simulation of transition between supercritical and subcritical conditions. Furthermore, an illustration of heat transfer models suitable for potential boiling crisis under near-critical pressure condition is introduced and presented. The code TACOS is then applied to simulate SWAMUP trans-critical test to validate its feasibility of simulating trans-critical transients. Furthermore, validations with the Edward-O'Brian blow-down experiment data and other codes’ results are illustrated to evaluate its capacity in simulating the fast blow-down progress under both sub-critical condition and supercritical condition. At last, the Loss of Coolant Accidents (LOCAs) with a small break size and a large break size occurring at the main coolant line of Chinese Super-Critical Water-cooled Reactor (CSR1000) are simulated. The results show that CSR1000 with its official safety system design can be cooled down during the considered accidents and code TACOS has good feasibility for safety analysis of supercritical water systems.