Study of Breeding Performance in a Heat Pipe Cooled Traveling Wave Reactor With Th and U Fuels

Heat pipe cooled traveling wave reactor (HPTWR) is a newly proposed heat pipe reactor. The HPTWR can achieve the low enrichment of loaded fuel, high power density, and long-term continuous operation for the power supply of decentralized electricity markets. Due to the excellent breeding capability of the HPTWR, the Th fuel is also added into the breeding fuel region of the reactor to achieve the Th-U fuel cycle in this work. The Monte Carlo code RMC is used to obtain the reactivity swing, propagation of axial power peak, burnup and the productions of bred fissile nuclides for the HPTWR with Th and U fuels. The study shows that the HPTWR with 14.3% 235U enrichment of ignition fuel and 20% 235U enrichment of breeding fuel can continuously operate for 41 years without refueling when the mass fraction of 232Th in heavy metals of breeding fuel region is 50% at the initial time. The propagation velocity of axial power peak and total burnup for the HPTWR with the Th and U fuels is about 0.3659 cm/years and 89.32 GWd/THM during the 41 years operation respectively. The productions of the bred 239Pu, 241Pu and 233U in the HPTWR with Th and U fuels are about 356.40 kg of 239Pu, 1.57 kg of 241Pu and 199.94 kg of 233U at the end of life respectively. The obtained results in this study demonstrate that the HPTWR can achieve the Th fuel breeding in the case of the low 235U enrichment loading (≤ 20%) and long-term continuous operation (> 40 years).