Preliminary neutronics and thermal analysis of a heat pipe cooled traveling wave reactor

Abstract

Heat pipe cooled traveling wave reactor (HPTWR) is a novel concept of heat pipe reactor, which adopts neutron breeding wave to pursue Uranium-Plutonium breeding. In this paper, the cladding material, power output, and axial breeding fuel region length of the HPTWR are optimized in order to achieve the safe operation of reactor with reactor neutronics and HP thermal analysis. Monte Carlo neutron transport code RMC is used to obtain the neutronics results (reactivity, consumption and breeding of nuclear fuel, and power distribution). A heat pipe (HP) code based on thermal resistance–capacitance network model (TRCNM) is developed to analyze the heat transfer characteristics of HP using the power distribution of fuel element obtained by RMC code in the optimized HPTWR. Results show the optimized HPTWR can achieve 70 MWth power output and 46 years continuous operation. The highest temperature peak of HP wall in the highest power fuel element of reactor appears at beginning of cycle (BOC) and is about 1800 K. Due to the flattening of axial power distribution with propagation of traveling wave, the temperature peak of HP wall gradually decreases to about 1784.6 K at end of cycle (EOC), which can reduce the thermal stress of HP wall and improve the safety of reactor. The corresponding heat transfer margin of HP in the highest power fuel element is always above 19.0% during the whole reactor operation, which helps to ensure the safe operation of the optimized HPTWR.