Florent Lemort

Test of actinide-lanthanide separation in an aluminum-based pyrochemical system

Abstract The investigation of the actinide and lanthanide distribution between a liquid metal and a molten fluoride salt shows a significant increase of the separation coefficient by using an aluminum-based pyrochemical system instead of a zinc-based system. The obtained values partly depend on the LiF/AlF3 ratio and can reach more than 30 000 when AlF3 is in excess with regard to the formation of the cryolite (Li3 AlF6). Furthermore, in the metal phase, the aluminum interacts with the lanthanides to a lesser extent than in other usual metallic solvents. This opens a new way to explore the feasibility of the separation of actinides and lanthanides in the field of nuclear fuel reprocessing.

Modeling and estimating the distribution of trivalent actinides and lanthanides between molten fluorides and liquid metal

Abstract Separation of actinides and lanthanides between a fluorinated phase rich in LiF and a metallic phase showed that the deviation ( E ) between the theoretical and experimental results for the trivalent actinides and lanthanides can be described using a relative ionic potential Δ PI between Li + and the cations An 3+ or Ln 3+ , such that for each of the two groups E = α Δ PI + β , where α is temperature-dependent and β varies with the nature of the system. The results obtained in the MSBR development program were analyzed to determine α at various temperatures for both series of elements, and to propose expressions for Δ G ° f (AnF 3 ) versus temperature in the liquid phase (where An represents Np, Am, Cm or Cf). E was measured for U(III) and La(III) in the LiF–CaF 2 /Zn–Mg system at 720°C, and an empirical model was developed to simulate the distribution of all the trivalent actinides and lanthanides in the same system.