Investigation of the eutectic reaction among core materials in a core disruptive accident of sodium cooled reactor is of importance since reactor criticality will be affected by the change in reactivity after eutectic reaction. In our previous study, a two-dimensional fast reactor safety analysis code, SIMMER-III, was extended to include a multi-phase model to simulate the eutectic reaction between stainless steel (SS) and boron carbide (B~4~C). 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 core materials including an 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% B~4~C-SS composition. In this study, we extended the eutectic reaction model for 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 B~4~C pellet was immersed into a molten SS pool. The eutectic reaction consumes solid B~4~C and liquid SS, and then the liquid eutectic composition is produced at the early stage of reaction due to the high temperature of molten SS. Movement of the eutectic material in the molten pool leads to the redistribution of boron element. Molten SS pool then freezes to solid SS and movement of eutectic material is stopped by surrounding solid SS. 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 results of post test analysis. Simulation results of boron distribution were reasonable in comparison with the experimental results.


Study on Eutectic Melting Behavior of Control Rod Materials in Core Disruptive Accidents of Sodium-Cooled Fast Reactors: Validation of a Multi-Phase Model for Eutectic Reaction Between Stainless Steel and Boron Carbide

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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