Impact of gamma-irradiation on the palladium behaviour in the PUREX process

International audienceThe PUREX process uses 30 percent Vol tri-n-butylphosphate (TBP) diluted in TetraPropylen Hydrogen (TPH, an hydrocarbon diluent) to selectively extract uranium(VI) and plutonium(IV) towards fission products such as ruthenium, molybdene, cesium, palladium, etc. In this process, the solvent is subject to radiolysis, which could result in a modification of the solution composition and the occurrence of cruds. The main consequence of these phenomena is a change in the extraction properties of the solvent, especially in terms of efficiency and selectivity. Many papers report detailed qualitative and quantitative investigations of TBP-TPH degradation due to radiolysis. However, very few data report the influence of the radiolysis on the palladium behaviour. Indeed, some degraded products could interact with palladium to form either complexes or precipitates.In this study, the impact of the radiolytic degradation of TBP-TPH on the palladium behaviour will be thoroughly discussed. For that purpose, a fine characterization of the precipitates formed by et61543;-irradiation of the biphasic system TBP-TPH//Pd-HNO3 will be detailed