An application of direct statistical method for kinetics parameters in TMSR-SF1

[Background] Kinetics parameters play an important role on reactor safety analysis and dynamic behavior. Thorium-based molten salt experiment reactor with solid fuel (TMSR-SF1) is a new kind of reactor. Using Monte Carlo code to calculate kinetics parameters is in favor of its nuclear safety license. [Purpose] This study aims at realizing the direct statistical calculation of kinetics parameters in Monte Carlo code, and applying this method to obtain the effective delayed neutron fraction and effective neutron generation time of TMSR-SF1. [Methods] We implant the direct statistical method into MCNP (Monte Carlo N Particle Transport Code) code by tallying the fission neutron type and fly time, and verify its accuracy with multiple ICSBEP (International Criticality Safety Benchmark Evaluation Project) benchmark. [Results] The benchmark kinetics parameters calculated by direct statistical method are consistent with experiment measured value (± 5% deviation). The effective delayed neutron fraction and effective neutron generation time of TMSR-SF1 we obtained, are close to that of conjugate flux method based on MCNP code. [Conclusion] It is reliable to use direct statistical method to calculate kinetics parameters of TMSR-SF1. (authors)