Study on the System Simulation for the Heat Pipe Failure Transient of Heat Pipe Cooled Reactor

Heat Pipe cooled Reactor (HPR) has the advantages of compact structure, high power capacity, high reliability, and inherent safety. It is often considered to have no loss of flow or loss of coolant accident during the heat pipe cooled reactor operation, because there is no flowing coolant working across the major equipment (the coolant only evaporates, condenses and transfers inside the heat pipe) and the working pressure is low. However, due to the limitations of the thermo-physical properties of the fluids inside the tube and the structure of the wick, the heat pipe has an inherent working temperature range, and the heat flux at the hot end is likely to change sharply which could result in the failure of the heat pipe. While the heat pipes are closely arranged in the reactor, an abnormal operation of a single heat pipe may lead to the continuous failure of multiple heat pipes around it in a short time. Thus, the impact of such accidents on the operation safety and reactor reliability should be considered in the heat pipe nuclear reactor design and safety analysis. This paper provides a system-level simulation scheme to analyze the possible consequences of such kind of accident in a rectangular heat pipe reactor. In addition, the important indexes safety margin of the reactor during the transient of heat pipe failure is evaluated and calculated.