A Neutron Diffraction Study of Molten LiCl-KCl-LaCl3

The LiCl-KCl salt system has generated significant industrial interest the use in next generation molten salt reactors, and for the processing of certain spent nuclear fuels. Experimental and theoretical structures of both LiCl and KCl have been reported since as early as the 1950s, however the structure of the eutectic composition (40.5 LiCl : 59.5 KCl (mol%)) remains theoretical. The low melting point (353 C) of the eutectic composition allows for the dissolution of additional cations, such as those resulting from fission or corrosion reactions, including lanthanides, at industrially achievable temperatures. In the proposed work we aim to determine the structure of the compositional end-members, LiCl and KCl, and to explore the structure of the industrially attractive eutectic composition, or LKE. LaCl3 will be incorporated into LKE and the influence of the molten structure observed as its concentration is increased, with pure molten LaCl3 also be characterised. Lithium-7 LiCl will be utilised to ensure high quality data is obtained, overcoming the issue of high neutron absorption from Lithium-6. Experimental data will be used in conjunction with machine learning molecular dynamics models to determine structure factors of these systems.