Understanding glass melt chemistry in thermal treatment of nuclear waste

This fully funded 3.5 year PhD project, which is part of the TRANSCEND programme, is intended to develop a deeper understanding of how glass chemistry can be used to maximise waste incorporation while minimising volatilisation during the nuclear waste vitrification. Specific aims are to understand the waste incorporation reactions and radionuclide incorporation mechanisms for a variety of representative wastes. These aims will be addressed by undertaking 1) investigations of quenched melts of a variety of glass forming compositions produced at various time intervals; 2) investigations of the final equilibrium glass compositions and 3) real time measurements of the off-gas from the melts.

While borosilicate glasses are most commonly used for nuclear waste immobilisation, such glasses have limited compatibility with, for example, wastestreams with significant halide, molybdate or actinide contents. Thus the project will look at the different behaviours of conventional borosilicate, aluminosilicate (calcium aluminosilicates have a greater capacity for chloride containing wastes) and titanosilicate (potentially attractive for high soda and molybdate wastes) glass and melts. Incorporation of specific species into a glass is determined both by the final glass structure and the role of specific species within that structure (both of which are related to the melt structure) as well as kinetically favoured species that are formed during the melt process, which if volatile, lead to notable losses from the melt. The precise wastes and glasses to be studied in this project will be decided through discussion with the industry funders as the project develops.

The successful applicant will work in the Immobilisation Science Laboratory at the University of Sheffield, a world-leaching centre for nuclear waste research, alongside 45 other PhD students. You will have access to the brand new £2M suite of dedicated radiation-controlled laboratory facilities and will have the opportunity to perform experiments using state-of-the-art facilities at the University. We strongly encourage applicants to take a short placement within the nuclear industry (e.g. NNL, Sellafield Ltd. etc.).

This industry funded project would suit a candidate with a 1st or 2:1 Bachelor or Masters degree in any of the following: materials science, chemistry, chemical engineering, physics, geology or related subjects.