Dynamic Safety Analysis of a Subcritical Advanced Burner Reactor

Abstract

Nuclear power provides the only technically credible option for impacting climate change in the next century. The ultimate disposal of long lived transuranics (TRU) in spent nuclear fuel is the central technical issue preventing the expansion of nuclear power. Georgia Tech's Subcritical Advanced Burner Reactor (SABR) aims to close the back end of the nuclear fuel cycle by destroying TRU. SABR is composed of 10 physically separate but neutronically coupled pool type fast reactors. In this thesis, we develop a customized dynamic safety model and use it to analyze the safety characteristics of SABR. We simulate Loss of Flow Accidents, Loss of Heat Sink Accidents, and Loss of Power Accidents. We analyze the effect of various shutdown mechanisms such as inserting control rods and shutting the fusion reactor off. The core avoids failure (no fuel melting or coolant boiling) for 50 % (failure of 1 of 2 pumps) Lost of Heat Sink (LOHSA) and Loss of Flow (LOFA) accidents without any corrective action being taken. For 100 % (failure of both pumps) LOFAs and LOHSAs, coolant boiling (1156 K) and fuel melting (1473 K) occur at about 25s and 35s, respectively, after pump failure unless corrective control action is taken before this time, in which case the core can be shut down without fuel melting or coolant boiling 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) unless some other means is provided for decay heat removal. We make recommendations on how to improve the passive safety characteristics of SABR.