Transient analyses on overpower transients of small modular natural circulation Lead-cooled fast reactor SNCLFR-100

Abstract In order to investigate the transient safety characteristics, Unprotected Transient Overpower (UTOP) and Protected Transient Overpower (PTOP) of small modular natural circulation lead-cooled fast reactor SNCLFR-100 were performed using MPC_LBE, a multi-physics coupled safety analysis code for lead-based reactor. The simulation results indicated that the negative reactivity feedback effect of the reactor during transient slowed down the accident process, and the natural circulation capability of the reactor ensured the heat removal from the core after accident. Under both UTOP and PTOP transient conditions, the peak temperatures of coolant and fuel pellet in the hottest channel of the core did not exceed the safety design limits. The reactor could re-establish a new steady state through natural circulation in UTOP transient, and it was shut down safely after reactor scram triggered in PTOP transient.