Comparison and analysis of breeding performance of common fuels for molten salt reactor

As the fourth generation advanced nuclear energy system, molten salt reactor has the advantages of good neutron economy, high intrinsic safety, on-line refueling and burn thorium fuel. For molten salt fast neutron reactor and molten salt thermal neutron reactor, the critical performance and conversion ratio of nine fuel salts commonly used in molten salt reactor at the beginning of cycle are calculated by MCNP5, and the factors affecting the conversion coefficient are analyzed by neutron balance method. According to the analysis of the calculated results at the beginning of cycle, ²³³U has higher average fission neutron number and smaller neutron capture cross section, which is conducive to improving the effective multiplication factor and fuel utilization. In addition, the neutron capture cross section of ²³Na in the reactor is larger than that of 7 Li, so the effective multiplication factor of fuel salt containing ²³Na is relatively low, but the influence of ²³Na in the thermal reactor is smaller, so ²³Na is more suitable for fast reactor. (authors)