UC Irvine

PUREX (Plutonium Uranium Reduction Extraction) is one of the most commonly used, and perhaps most studied solvent extraction (SX) process for the recycling of uranium and plutonium from spent nuclear fuel. This process employs tributyl phosphate (TBP) as its extracting agent which facilitates the transfer of metal ions from the aqueous phase into the organic solvent by forming complexes around the metal ions. However, the metal extraction mechanism and phase separation involve many molecular level events, including third phase formation, that are not well understood. This research utilizes atomistic molecular dynamics (MD) simulations in conjunction with experimental work to elucidate molecular-level processes involved in a SX system. A major part of this research project is dedicated to the optimization and validation of the force fields for the species that are present in the SX system. Utilizing the optimized force fields for each species for MD studies, in conjunction with experimental works, we gain new insights into the conformational behaviors of the TBP molecule in its bulk liquid as well as in n-dodecane solution. We also report, for the first time, the dimerization and trimerization constants of TBP in several n-alkane diluents via both MD and FTIR studies.