Safety analyses of 10 MWth Forced Circulation LBE-cooled Fast Reactor during unprotected transients

Abstract

In order to evaluate its safety performance, a 10MWth Forced Circulation LBE-cooled Fast Reactor (FCLFR) was simulated by a Neutronics and Thermal-hydraulics Coupled simulation program (NTC) under three transient accidents which were unprotected transient overpower (UTOP), unprotected loss of flow (ULOF) and unprotected loss of heat sink (ULOHS). The simulation results showed that the reactor could survive both ULOF and UTOP transients and a new steady state was re-established without human or active device intervention. The ULOHS simulation showed that the core power could decrease to the decay heat level due to the negative reactivity feedbacks. At the later stage of this transient, the core temperatures increased very slowly, providing sufficient time (at least 4500s) for the operator to activate the decay heat removal (DHR) system.