Dynamic Safety Analysis of a Subcritical Advanced Burner Reactor

A customized dynamic safety model is developed and used to analyze the safety characteristics of the Subcritical Advanced Burner Reactor (SABR), a fast transmutation reactor driven by a tokamak fusion neutron source. Loss-of-flow accidents (LOFAs), loss–of–heat sink accidents (LOHSAs), and loss-of-power accidents (LOPAs) are analyzed taking into account the effects of feedback mechanisms, control rod insertion, and terminating electrical power to the neutron source. The core avoids fuel melting and coolant boiling without corrective action for 50% (failure of one of two pumps) loss of heat sink (LOHSA) and loss of flow (LOFA). For 100% (failure of both pumps) LOFAs, LOHSAs, and LOPAs without corrective action, coolant boiling (1156 K)/fuel melting (1473 K) occur at about 25 s/36 s, 35 s/84 s, and 25 s/36 s, respectively, after pump failure unless corrective control action is taken before this time, in which case the core power can be reduced to the decay heat level by shutting off the plasma power source. The present passive heat removal system is not sufficient to remove the decay heat, and both fuel melting and coolant boiling ultimately occur in the 100% LOFAs and LOHSAs (failure of both pumps) in either the primary or secondary system indicating the need to provide other means for decay heat removal.