Brannerite glass ceramic wasteforms for immobilisation of nuclear fuel residues.

Lead Research Organisation: University of Sheffield
Department Name: Materials Science and Engineering

Abstract

This project seeks to address the requirement for treating damaged and degraded nuclear fuel materials present on the Sellafield site, immobilising these highly radioactive wastes in a glass-ceramic wasteform suitable for long term storage and final disposal. These materials range from wet sludges to dry granular materials. At present, there is no accepted waste treatment route or this material.

We propose to develop a suite of novel glass-ceramic wasteforms for this purpose, based on synthetic brannerite, UTi2O6. The fuel residues are principally 96% UO2, with 3% fission products and 1% plutonium dissolved as a solid solution. It has been shown that geochemically altered natural mineral brannerites retain their uranium inventory for hundreds of millions of years, even after radiation induced amorphisation by alpha-decay. Natural brannerites have been shown to incorporate up to 4 wt% water, providing confidence that a synthetic brannerite wasteform will be compatible with processing of wet fuel residues.

This project will design and develop develop glass-ceramic brannerite wasteforms, in which the highly durable brannerite ceramic phase, based on UTi2O6, incorporates long lived U and Pu, with a less durable glass phase to incorporate the short lived fission products.

These ceramic wasteforms will be fabricated using the unique Hot Isostatic Pressing (HIP) facility for radiological materials, at the University of Sheffield. Materials will be characterised by X-ray diffraction, electron microscopy with X-ray analysis, Raman spectroscopy, pycnometry,thermal analysis, and U L3 edge X-ray Absorption Spectroscopy (collaboration with Brookhaven National Laboratory).

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509735/1 01/10/2016 30/09/2021
1963750 Studentship EP/N509735/1 16/10/2017 15/03/2021 Malin Dixon Wilkins
 
Description Insights into the underlying crystal chemistry of the brannerite structure, as full ceramic phases and as ceramics phase within glass-ceramic composite systems. This work encompasses a wide range of different brannerite-structured materials, with the aim of furthering our understanding of these materials to ensure our knowledge base of candidate nuclear waste disposal materials is comprehensive.
Exploitation Route The research I am currently undertaking is essential chemistry that we need to understand before this material can be properly used as a nuclear wasteform. By giving the nuclear industry (espeically the decommissioning sector) the underpinning science, they can begin to examine the scale-up of these materials.
Sectors Energy,Environment,Other

 
Description THERAMIN Project - Thermal treatment for radioactive waste minimization and hazard reduction 
Organisation THERAMIN Project
Country Finland 
Sector Charity/Non Profit 
PI Contribution The THERAMIN project is a Euratom funded training, research, and innovation project, with a focus on thermal treatment technologies for radioactive waste minimization. We (me and colleagues from the University of Sheffield) have expertise in one such technology - Hot Isostatic Pressing (HIP) My contributions include attendance at the THERAMIN summer school, where I presented a poster including some preliminary work I have done on HIPed UTi2O6 glass-ceramics, as well as attendance at the end of project THERAMIN conference, where I presented a 15 minute talk on further work I have done on HIPed UTi2O6 glass-ceramics.
Collaborator Contribution The THERAMIN project is a Euratom funded training, research, and innovation project, with a focus on thermal treatment technologies for radioactive waste minimization. We (me and colleagues from the University of Sheffield) have expertise in one such technology - Hot Isostatic Pressing (HIP). The other partners have expertise in other thermal treatment technologies, including in-can vitrification, the GeoMelt technology, thermal gasification, and cement encapsulation. I had the opportunity to learn about these techniques, as well as visit the CEA Marcoule site and see some of their equipment in-person. Other parts of the THERAMIN project include waste acceptance criteria, as well as organisations working on nuclear waste acceptance criteria and related policy.
Impact Conference proceedings article, currently (11/02/2020) in review, for publication in a special edition of IOP conference proceedings series of books.
Start Year 2017