Investigating porosity changes and stress mechanics of corroding nuclear wastes under confined expansion

Summary

As the UK prepares to invest in new operational nuclear power plants, industry and research organisations are also looking to decommission the UK’s existing nuclear legacy facilities. Fuel cladding, and corrosion products thereof, represent one of the major challenges to waste retrievals and storage at Sellafield and the wider nuclear industry. Waste is currently housed in aged storage facilities pressing retrieval and interim storage (such as the Magnox Swarf Storage Siloes) prior to immobilisation and geological storage. The volume and porosity changes arising are complex, and overall porosity increase and volume expansion have only been observed in unconfined cases, where reaction rates are appreciable.

This PhD project will work alongside leading teams within the University of Leeds and Sellafield Ltd, to investigate the nature of waste evolution under storage conditions in order to predict volume changes and resulting forces generated on confinement packaging. Specifically, under interim storage, Magnox alloy undergoes a series of physical and chemical changes; such as corrosion reactions forming brucite, as well as with CO2 to form hydromagnesite and other magnesium hydroxycarbonate phases as a soil/clay like sediment bed, which will gradually dry-out over long timescales. Behaviour under confined conditions and over the timescales of storage (many decades) is poorly understood, resulting in significant costs to the UK taxpayer to ensure wastes are safely stored. This is an exciting interdisciplinary project, combining chemistry and civil engineering with soil mechanics and geotechnics. It will also involve a close working relationship with the nuclear industry.

CDT information

This project is part of the Centre for Doctoral Training (CDT) in SATURN (Skills And Training Underpinning a Renaissance in Nuclear). It is led from the University of Manchester and includes leading nuclear research universities in the North of England and Scottland (University of Leeds, University of Sheffield, Lancaster University, University of Liverpool, University of Strathclyde). We aim to deliver the next generation of nuclear researchers to help the UK achieve its Net Zero targets and beyond, in a collegial cohort environment. The CDT will also include technical training in the nuclear fuel cycle to ensure all candidates are familiar with the nuclear sector, and specialist research skills training.

SATURN_Nuclear_CDT

Candidates will have, or be due to obtain, a Master’s Degree or equivalent from a reputable university in an appropriate field of Engineering. Exceptional candidates with a First Class Bachelor’s Degree in an appropriate field will also be considered. Applicants are advised to check with the relevant School prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.