Solubility of PuF3 in molten 2 LiF-BeF2

Equilibrium distribution of lanthanum, neodymium, and thorium between fluoride salt melts and liquid bismuth

“…Studies of lanthanide and thorium extraction from fluoride salt melts into liquid bismuth with lithium admixtures as a reducing agent are of interest for the purification of liquid salt reactor (LSR) fuel salts from soluble fission products in the form of lanthanide and actinide trifluorides [1][2][3][4][5][6][7]. Ferris [3,4] and, later, Moriyama [5,6] studied this type of extraction for one and two liquid LSR schemes with fuel salts based on LiF-BeF 2 and LiF-BeF 2 -ThF 4 .…”

“…Ferris [3,4] and, later, Moriyama [5,6] studied this type of extraction for one and two liquid LSR schemes with fuel salts based on LiF-BeF 2 and LiF-BeF 2 -ThF 4 . They showed that the general equation of the reaction describing the equilibrium distribution of element M between fluo ride salt melt and liquid metal (Bi) had the form MF n(salt) + nLi (Bi) = M (Bi) + nLiF (salt) , (1) where n is the valence of extracted element M in the salt phase at a given temperature.…”

“…Under experimental conditions, the x LiF value was almost constant, and the concentrations of solutions in each phase were fairly low [1][2][3]. It fol lows that the activity coefficients of all the compo The element (extracted element and lithium) dis tribution coefficient between the liquid metallic and salt phases is determined as the ratio between its mole fractions in liquid metal and salt melt, (4) where . An analysis of the separation data on lanthanides and actinides in two phase molten flu oride salt/liquid metal systems at 500-700°С [1][2][3][4][5][6][7] showed that salt mixture composition variations sub stantially changed salt distribution coefficients.…”

“…The D(М 1 )/D(М 2 ) separation coefficient between trivalent elements does not depend on the fraction of LiF in the fuel salt because the influence on their extractibility is similar in character [3][4][5][6][7]. The separation of rare earth metals from each other is [3][4][5][6][7]. Tri and tet ravalent elements form complexes (e.g., LiLaF 4 and Li 2 ThF 6 ) due to their strong polarizing ability, whereas mono and divalent elements show weak tendency to complex formation.…”

“…At the same time, the table shows that, for quite a number of two phase compositions, the K' value from (4) decreases for each element as the con centration of free fluoride ions in melts increases: EFF = (LiF, mol %)-2(ВeF 2 , mol %)-3(ThF 4 , mol %). Some data, however, show that this simple correlation cannot fully take into account all the aspects of the influence of solvent composition [3][4][5][6][7]. In addition, in modern concepts of fast LSR burners and multipli ers, the concentrations of lanthanides and actinides in fuel salts, including LiF-NaF-BeF 2 , LiF-NaF-KF, or LiF-BeF 2 -ThF 4, compositions, can reach 2-5 and 0.1-0.3 mol %, respectively.…”