Ab-initio molecular dynamics study of lanthanides in liquid sodium

Abstract To mitigate the fuel cladding chemical interaction (FCCI) phenomena in liquid sodium cooled fast reactors, a fundamental understanding of the lanthanide (Ln) transport through liquid Na Cs filled pores in U Zr fuel is necessary. In this study, we investigate three abundant Ln fission products diffusion coefficients in liquid Na at multiple temperatures. By utilization of Ab-initio Molecular Dynamics, the Ln diffusivities are found to be in the magnitude order of liquid diffusion ( 10 − 5 cm 2 / s ) and the temperature dependence of the diffusivity for different lanthanides in liquid sodium was explored. It is also observed that dilute concentration of Pr and Nd led to a significant change in Na diffusivity. The structural and electronic properties of Na Ln metallic systems have been investigated. The total coordination number shows dependence on both the temperature and the composition.