Development of Monazite based Glass-Ceramic Nuclear Wasteforms for Plutonium Immobilization

Project Code: EPSRC_2023_09

Project Introduction

To ensure the safe disposal of plutonium, different scientific technologies are being studied to confine it within ceramics or glass-ceramic matrix composites. Currently, the nuclear industry considers Hot Isostatic Pressing (HIPing) as the most promising technology for the synthesis of such materials. Research on the subject has started in the past 5 to 10 years with UK nuclear industry interested in understanding the fundamental processes affecting the material's properties and the technical aspects related to the HIPing of nuclear materials. This PhD project concerns with the development of monazite-based glass-ceramic matrix composites using our newly established HIPing facility combining the chemical flexibility of the glass phase and excellent chemical durability of the ceramic phase to design novel materials for plutonium management. 

Project Details

Background 

To ensure the safe disposal of plutonium, different scientific technologies are being studied to confine it within ceramics or glass-ceramic matrix composites. Currently, the nuclear industry considers Hot Isostatic Pressing (HIPing) as the most promising technology for the synthesis of such materials. There is ongoing research on understanding the fundamental processes affecting the material properties and the technical aspects related to the HIPing of nuclear materials. This PhD project concerns with the development of monazite-based glass-ceramic matrix composites using HIPing combining the chemical flexibility of the glass phase and excellent chemical durability of the ceramic phase to design novel materials for plutonium and other minor actinide management. 

The research will be undertaken on the synthesis, characterisation, and evolution under simulated disposal conditions of monazite-based glass-ceramics. The ceramic component in the glass-ceramic is chosen based on mineralogical evidence. The natural mineral monazite, which contains radioactive uranium and thorium, has remained structurally and chemically stable on a geological timescale and hence, synthetic monazite is proposed as a promising ceramic wasteform. Monazites crystallize in a monoclinic crystal system and the rare earth (RE) site is coordinated to nine oxygen atoms resulting in the formation of a distorted REO9 polyhedron. As a result of distortion, the RE site in monazite offers greater chemical flexibility and allows for the incorporation of plutonium in addition to minor actinides (e.g., Np, Am, Cm) and neutron absorbers (e.g., Gd). The glass in the glass-ceramic will be an alumino-borosilicate glass which can accommodate other radioactive impurities arising from the nuclear fuel cycle. Thus, glass-monazite matrices will enable a higher waste loading while maintaining superior structural and chemical durability along with the necessary chemical flexibility to accommodate any impurities. 

Research Objectives 

This project deals with the synthesis and characterization of cerium-doped glass-monazite samples with cerium acting as a non-radioactive surrogate for plutonium and studying the radiation stability and chemical durability of the synthesised wasteforms. The project involves using solution routes combined with HIPing for materials synthesis and characterisations tools such as XRD, SEM, EDS, EBSD, TEM, ICP-MS and nanoindentation for materials qualification. The synthesised materials will be irradiated using our MIAMI TEM with an in-situ ion irradiation facility and DCF-Cumbria to evaluate their radiation stability. Corrosion studies simulating geological disposal conditions will be undertaken to establish the chemical durability of the materials. Scientific findings from synthesis, irradiation and corrosion studies will be utilised to further improve the design and chemical composition to obtain the necessary wasteform that satisfies the industry requirements. 

Characterisation Techniques 

 The candidate will be trained in the use of following techniques/tools.  

1. Materials synthesis using Hot Isostatic Pressing (HIPing) 
2. Materials characterisation using XRD, XRF, SEM, EDX, FIB, TEM and nanoindentation. 
3. Corrosion studies using ICP-MS/OES, SEM and cryo-TEM. 

Entry Requirements

Applicants are expected to have a masters level degree in Physics, Chemistry, Materials Sciences, or a related subject. Basic knowledge of solid-state inorganic chemistry, crystal structures, and characterization techniques (e.g., XRD, SEM) is desirable, but not essential.  

This call is open to UK Applicants only. 

Applicants should be of outstanding quality and exceptionally motivated.

The studentships are funded for 3 years subject to satisfactory annual performance and progression review, and will provide for tuition fees and a tax-free stipend paid monthly.

Please note that there are more projects than funded studentships available and therefore this is a competitive application process which will include an interview. Shortlisted candidates will be contacted for an interview in person or via Teams. After interview the most outstanding applicants will be offered a studentship.

Queries about the application process are welcome and should be directed by email to [Email Address Removed].

Informal enquiries about individual projects should be directed to the lead supervisor listed for each project.

Application details

• Complete the Expression of Interest Form 2023
• Provide copies of transcripts and certificates of all relevant academic and/or any professional qualifications.
• Provide references from two individuals

Completed forms, including all relevant documents should be submitted via-email to [Email Address Removed]

Please note: if you do not attach all the relevant documentation prior to the closing date of 15 June 2023 your application will not be considered.