Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 4; Validation of a multi-phase model for eutectic reaction between stainless steel and boron carbide

Liu, X.*; Morita, Koji*; Yamano, Hidemasa   

In our previous study, a two-dimensional fast reactor safety analysis code, SIMMER-III, was extended to include a physical model to simulate the eutectic reaction between stainless steel (SS) and BC. Based on experimental knowledge on eutectic reaction, the growth of eutectic material was modeled according to a parabolic rate law. Heat and mass transfer behaviors among reactor materials including a eutectic composition in solid and liquid phases were also modeled considering both equilibrium and non-equilibrium processes in phase change. Physical properties of the eutectic composition were also formulated based on experimental measurements for 5 mass% BC-SS composition. In this study, we extended the eutectic reaction model to SIMMER-IV, a three-dimensional counterpart of SIMMER-III. We performed validation analysis using SIMMER-III and SIMMER-IV with the developed model based on an experiment, where a BC pellet was immersed into a molten SS pool. Boron concentration in the pool was measured at several time points and the boron concentration after solidification of the molten pool was compared with the experiment post analysis result. Simulation results of boron distribution are comparable to the experimental results.