Abstract
Materials from GeoMelt® In-Container Vitrification (ICV)™ of simulant UK nuclear wastes were characterised to understand the partitioning of elements, including inactive surrogates for radionuclide species of interest, within the heterogeneous products. Aqueous durability analysis was performed to assess the potential disposability of the resulting wasteforms. The vitrification trial aimed to immobilise a variety of simulant legacy waste streams representative of decommissioning operations in the UK, including plutonium contaminated material, Magnox sludges and ion-exchange materials, which were vitrified upon the addition of glass forming additives. Two trials with different wastes were characterised, with the resultant vitreous wasteforms comprising olivine and pyroxene crystalline minerals within glassy matrices. Plutonium surrogate elements were immobilised within the glassy fraction rather than partitioning into crystalline phases. All vitrified products exhibited comparable or improved durability to existing UK high level waste vitrified nuclear wasteforms over a 28 day period.
Highlights
Radioactive wastes arising from current and legacy nuclear fuel cycle operations pose a signiicant decommissioning challenge to the UK due to the volume and complexity of the wastes
Both the light and dark region XRD patterns are displayed in Fig. 2, revealing a largely glassy material with relections identiied as clinoenstatite (MgSiO3) and alpha iron
The materials characterised in this study were produced through incontainer vitriication of UK simulant wastes, combined with glass forming additives
Summary
Radioactive wastes arising from current and legacy nuclear fuel cycle operations pose a signiicant decommissioning challenge to the UK due to the volume and complexity of the wastes. Higher activity radioactive wastes in the UK include some irradiated nuclear fuels and highly active liquors from reprocessing This category includes larger volume, moderate activity intermediate level wastes (ILW) such as: sludges, locs, activated metals, ion-exchange resins, and other miscellaneous materials (Nuclear Decomissioning Authority, 2016, 2019a). These typically arise due to fuel handling operations, site decommissioning, contact handling of plutonium, and operational activities. This has driven research, both in the UK and internationally, towards expanding vitriication or other thermal treatment technologies for ILW waste streams as an option within a toolkit of immobilisation technologies (Radioactive Waste Management (RWM), 2017; Bennett et al, 2001)
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