The investigation of thermal neutron scattering data for molten salt Flibe

Abstract

Based on the dynamics of Flibe (2LiF-BeF 2 ), the thermal neutron scattering library (TSL) is generated by NJOY in this paper. We worked on the TSL data through the microscopic analysis. With the increas of temperature and translational weight of liquid Flibe, the inelastic scattering cross section decreases and the average energy of secondary neutron increases. Using TSL of Flibe, the critical calculation for molten salt reactor is also conducted by MCNP. Result shows the k eff is influenced by thermal neutron scattering obviously (about 0.8%). It is suggested that thermal neutron data should be taken into account in molten salt reactor.

Key Nuclear Data Impacting Reactivity in Advanced Reactors

“…Thermal scattering data for FLiBe-a compound combining LiF and BeF2-is currently under preparation and is intended to be included with the next ENDF/B release (Zhu and Hawari 2017). In reported test calculations in which researchers processed their own FLiBe data, an impact in the range 260-800 pcm was found for the multiplication factor in a molten salt system containing FLiBe, the magnitude of the effect being dependent on the temperature (Mei et al 2013).…”

“…Since these uncertainty data are missing in the released libraries, a specific quantification of the impact cannot be performed. However, an impact on the order of few hundred pcm can be inferred since an impact of the consideration of FLiBe thermal scattering data in the range 260-800 pcm was found for the multiplication factor in a molten salt system as described in Section 4.2 (Mei et al 2013).…”

Effect of FLiBe thermal neutron scattering on reactivity of molten salt reactor

“…where E and E ′ are the incident and outgoing neutron energy, µ is the cosine of the scattering angle, σ b is the characteristic bound scattering cross section of material, and κT is thermal energy in eV [1]. S (α, β) is computed using phonon spectrum, which is performed by LEAPR module of NJOY.…”

“…In a thermal neutron reactor, when neutron energy exceeds 4 eV, the binding energy within the molecule is not important in the process of neutrons colliding with the target nucleus [1]. It can be assumed that the target nucleus is stationary and unbound.…”

Thermal neutron scattering data for liquid molten salt LiF-BeF2

“…Several works have been done to generate the thermal neutron scattering data for liquid molten salt LiF-BeF2. Mei and Cai [5] generated the thermal neutron scattering data based on the dynamics of for molten salt Flibe. They used the solid crystalline models and density functional theory (DFT) simulations to calculate the solid-type spectrum and performed the effective width model [6] to treat the diffusive mode in calculations.…”