UF4, ThF4 Solubility in LiF–NaF–KF Melt

Fast-Spectrum Fluoride Molten Salt Reactor (FFMSR) with Ultimately Reduced Radiotoxicity of Nuclear Wastes

“…In addition to the predicted solubility data from thermodynamic calculations [2], recently actualized high solubility data of various fluorides of actinides and lanthanides specifically in the LiF-NaF-KF eutectic mixture (traditionally named as FLiNaK) [3][4][5][6] reportedly could allow utilizing the high enough energy neutrons for the U-Pu breeding cycle aided by a high heavy element inventory (2.8 t/m 3 ) and a small neutron moderating capability [7].…”

“…The author and associates have successfully performed a follow-up calculation not only for FLiNaK but also NaF-KF-UF 4 system as a matrix of the fuel salt [8,9]. Their efforts have borne a fruit as a nuclear reactor plant using a mixture of NaF-KF-UF 4 fertile and NaF-KF-TRUF 3 fissile as the fuel salt incorporated with designated online chemical processes based upon the oxide selective precipitation process with extremely low heavy element released to the environment which was nominated as the fast-spectrum fluoride molten salt reactor (FFMSR) [10][11][12].…”

“…During the freezing process, almost 75% of the fuel salt was solidified at 500°C as the same composition as the liquid phase. Eventually 0.47LiF-0.515BeF 2 -0.015ThF 4 containing very small amount of 233 UF 4 solidified as eutectic at 370°C [13]. This freezing process was evaluated as nuclear criticality safety in the fuel salt drain tank, and it became as a basis of the technological feasibility.…”

“…In serious attempt to use hexagonal PuF 3 as a fissile instead of monoclinic 233 UF 4 in 0.72LiF-0.16BeF 2 -0.12ThF 4 , it had been treated as the solubility of PuF 3 . The term "solubility" has been used as a convenient synopsis of "liquefied fraction" on the phase diagram [14].…”

“…The elaborated solubility measurements in FLiNaK by Russian scientists [3][4][5][6] should have been more appropriately respected if they had made the chemical composition of alkali fluoride matrix of liquefied samples analytically quantified instead of their customary practice in which the matrix had been always assumed as FLiNaK, even if they have found no UF 4 or PuF 3 but 2KF-UF 4 , 7KF-6UF 4 , KPu 2 F 7 , KPuF 4 , and NaPuF 4 in the solidified residue by the X-ray diffractometric analysis.…”