Modeling and Safety Analysis of Sco2 Brayton Cycle Reactor System Under Loss of Coolant Accident (Loca)

Abstract

In this work, the SCO2 blowdown model is developed, the system transient behavior during the LOCA process is simulated, and the threat to the main equipment is evaluated. The results show that the accident process is closely related to the SCO2 state at different break locations. When LOCA occurs at the reactor inlet and outlet, the break discharge rate is small, but the reactor fuel temperature will increase significantly at the accident late stage. The compressor outlet LOCA has the largest discharge rate and the shortest coolant phase transition time (720 s, break diameter is 4 mm). In addition, the pre-pressurized containment can effectively reduce the amount of coolant leakage and maintain SCO2 in the supercritical state. However, for the compressor inlet LOCA, if the break area is further increased, even with the protection of the containment and inventory control system, the supercritical failure of SCO2 is inevitable.

Keywords: Supercritical carbon dioxide, Brayton cycle, LOCA, Safety analysis, Critical flow, Phase transition