Effect of MOx composition and homogeneity on disposal performance

About Us

The Nuclear Decommissioning Authority (NDA) has established the Plutonium Ceramics Academic Hub at the Universities of Manchester and Sheffield (PUMaS), focused on underpinning the development of ceramic materials and technologies for the safe and secure disposition of the UK’s inventory of plutonium. This represents one of the most significant challenges facing the UKs programme of remediation and restoration of the Sellafield site, expected to be complete in the 2100s.

The PUMaS hub will support ~20 PhD students along with research staff, creating a vibrant and dynamic research environment with PhD cohort training, skills and networking events built into the PhD programmes. As a member of the PUMaS hub you will be based within state-of-the-art facilities such as the Henry Royce Institute, the UKs centre for advanced materials science, giving access to and training on leading materials science and engineering techniques.

This PhD will include industrial supervision from either NDA, Sellafield Ltd. or Nuclear Waste Services (NWS) to provide focus on tackling industrially significant issues with regards to the safe and secure disposition of the UKs inventory of plutonium and this will permit exchange of your work directly to the industry partners. Furthermore, there will be extensive opportunities to travel and attend conferences and meetings within the UK and internationally as well as collaborate with our academic and industry partners – accessing national or international facilities, for example at the UK National Nuclear Laboratory (UKNNL), Diamond Light Source (DLS) or the European Synchrotron Radiation Facility (ESRF).

About the Project:

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

Expectations and Rewards

During the PhD you will be expected to:

–         Work with and support the PUMaS Hub, nuclear fuels and RADER research groups

–         Have a sound work ethic allowing you to manage your project with an independence.

–         Provide regular updates and technical outcomes to your industry supervisor at NDA, SL or NWS and present updates at annual NDA and NWS conferences

–         Attend and present at both local and international conferences.

–         Partake in graduate teaching, supervision or training of Masters students

–         Be able to obtain baseline security vetting (BPSS)

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.