PhD Studentship: Effect of MOx Composition and Homogeneity on Disposal Performance

No. of candidates: 1

This project is fully funded by the Nuclear Decommissioning Authority (NDA) and includes tuition fees at the Home (UK) rate and standard annual UKRI stipend, which is £20,780 for academic year 2025/26.

Disposal mixed uranium and plutonium oxide (D-MOx) is a potential candidate for disposition of the UKs Pu inventory, immobilising it within a stable form prior to disposal in a geological disposal facility, a highly engineered subterranean structure designed to store the waste for >100,000 years. Historically, two industrial scale powder processing routes have been used to manufacture MOx materials, the micronized master blend (MIMAS) the Short Binderless Route (SBR). Due to the differences in the powder mixing the resultant MOx pellets contain varying levels of Pu homogeneity in the final product, for D-MOx the addition of neutron poisons during the different powder processing stages may also lead to variation in their homogeneity through the pellet. It is unclear the effect that these Pu rich islands and the degree of neutron poison homogeneity will affect the performance under disposal conditions, where issues such as aqueous durability are a key concern due to groundwater penetration. Thus, to inform D-MOx manufacturing processes an understanding of the effect of the Pu and neutron poison homogeneity on performance this project will look to answer the following using surrogate (non-active) and uranium active trials.

• How does powder processing and final homogeneity of the ceramic affect its performance?
• How do the key differences in the microstructure, chemistry and physical properties fundamentally affect this performance?

For this project, you will be based at the University of Manchester within the Nuclear Fuels and Radioactive Waste and Environment research groups. You will have access to state-of-the-art nuclear laboratories within the Henry Royce Institute and National Nuclear User Facilities (NNUF) for Radioactive waste managing and environmental remediation (RADER). You will utilise (where necessary), radioactive materials handling facilities, advanced materials characterisation techniques such as scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray diffraction (XRD) to study the materials at the micro and nanoscale and analytical techniques such as mass spectrometry (MS) as well as access to national and international facilities for example synchrotron based experiments.

More information on these facilities can be found;

• Henry Royce Institute Nuclear Facilities
• https://www.nnuf.ac.uk/simfuel-and-alpha-active-material-manufacturing-and-characterisation-facility
• https://www.nnuf.ac.uk/rader

There will be many rewards:

• Working as part of a large and experienced team across the cohorts will ensure a supportive environment and that you will always have someone to help.
• Opportunities to develop training and skills in a range of technical areas including radioactive materials handling, state of the art materials manufacturing, characterisation and testing equipment.
• Flexible and hybrid working is supported.
• Receipt of a competitive, tax-free stipend.
• Numerous opportunities for local and international collaboration and travel.
• Opportunities to develop a range of non-technical skills (presentation, organisation, leadership) through bespoke training programme of the Hub, mentoring and a broad range of university training and development courses.

To apply, please contact Dr Robert Harrison - r.w.harrison@manchester.ac.uk. Please include details of your current level of study, academic background and any relevant experience and include a paragraph about your motivation to study this PhD project.

Deadline: 31.07.25

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