Development of a radioactive waste decontamination process - Application to chemically decontaminated metal alloys

The use of nuclear energy makes it possible to produce large amounts of electricity while minimising the production of greenhouse gases. However, the management of nuclear waste remains a major challenge, particularly contaminated metal waste. Chemical decontamination (eg. COREMIX) is very effective, but generates large volumes of secondary effluents, which in turn require costly decontamination using specific resins. This work focuses on the development of a pre-treatment process for radioactive metal effluents with the aim of reducing the amount of resins required. To this end, a hydroxide precipitation protocol was developed on synthetic samples before being optimised on simulated samples and validated on radioactive effluents. Other precipitation methods such as sulphide, phosphate and electrocoagulation were investigated to make the protocol versatile and adaptable on a large scale. Although adjustments had to be made to suit the composition of the waste, the protocols developed enabled the effluents to be effectively decontaminated while significantly reducing the volume of resin required. (author)