Preliminary application of eutectic reaction model on boron carbide and stainless steel to severe accident simulation of sodium-cooled fast reactors

Yamano, Hidemasa   ; Morita, Koji*

For a severe accident (SA) simulation of sodium-cooled fast reactors, a eutectic reaction model between boron carbide (BC) and stainless steel (SS) has been developed to be incorporated into the SA simulation codes: SIMMER-III/IV. To confirm the applicability of SIMMER-IV involving the eutectic reaction model to reactor simulations, this study has preliminarily applied this code with the newly developed physical model to a SA simulation of a large-scale SFR designed in Japan. The simulation results show that the eutectic reaction is caused by the contact between the liquid SS and the broken BC pellets which are released to the coolant channel after the failure of cladding which is melted by the mixture of liquid SS and fuel particles coming from the neighboring fuel assemblies. The liquid eutectic material formed by the reaction stayed in the control assembly and the neighboring fuel assemblies. This preliminary simulation shows that the spreading area of BC-SS eutectic formation is limited within this calculation time.