Pyroprocessing of spent nuclear fuels is an electrochemical separation method where spent metallic fuel is dissolved in a molten salt bath to allow uranium (U) and plutonium (Pu) to be isolated from fission products (FPs) and other impurities. This allows the useful materials to be reused in mixed oxide fuel (MOx) or further refined to new reactor fuel. Monitoring the changing concentrations of U, Pu, FPs and other species inside a molten salt vessel presents a unique challenge which laser-induced breakdown spectroscopy (LIBS) may be able to overcome, due to its ability to simultaneously analyse multiple elements using a single measurement with stand-off capability in situ. In this study, samples of praseodymium (Pr), holmium (Ho) and erbium (Er) chloride (LnCl3) in LiCl + KCl eutectic (LKE) salt were analysed with LIBS. Multiple laser pulse energies were tested to maximise the signal to background ratio, the best results were obtained at the lowest pulse energy of 85 mJ per pulse. Forward interval Partial Least Squares (iPLS) regression was used to create predicted versus measured concentration models for each element. This method achieved Root Mean Squared Error of Cross Validation (RMSECV) values of between 3.20 × 10-3 and 16.3 × 10-3 mmolLn gLKE-1 for single lanthanide samples and 2.84 × 10-3 and 7.62 × 10-3 mmolLn gLKE-1 for mixed samples of all three lanthanide elements. Limits of quantification of between 1000 and 9000 ppm suggest LIBS should be a candidate for on-line analysis of elemental concentrations during pyroprocessing.

The feasibility of employing ion-exchange resins for the selective removal of uranium from a complex waste effluent has been investigated. The source of the effluent is a treatment process to reduce the volume of a spent uranium containing catalyst prior to its immobilisation and disposal in South Korea. Commercial anion exchange and chelation resins have been screened, along with an in-house synthesized polyamine functionalized resin. The Langmuir isotherm model produced the best fit for UO₂ ²⁺ binding to all resins, with Purolite MTS957, a mixed sulfonic/phosphonic acid functionalised resin, showing the highest equilibrium adsorption capacity for UO₂ ²⁺, 96.15 mg g⁻¹. The Modified Dose-Response Model was found to adequately represent breakthrough across all flow rates used and for all resins tested under dynamic testing conditions. The maximum uranium loading capacities under dynamic conditions for simulant and real wastes were established as 131.52 mg g⁻¹ and 68.62 mg g⁻¹, respectively. Purolite MTS957 effectively decontaminated the real effluent to uranium levels below the Korean release limit of 1 mg L⁻¹. Over 99.9% uranium was successfully eluted from the resin bed in under 20 BV with a mixed sodium carbonate/sulfate eluent.