Glass-Ceramic Wasteforms for High Level Wastes from Advanced Nuclear Fuel Reprocessing

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

Abstract

A key barrier to maturation and exploitation of glass-ceramic technology, for immobilisation of high activity waste from nuclear fuel recycle, is the gap in fundamental understanding of the molecular-scale mechanisms of phase separation and crystallization, that lead to the development of the desired phase assemblage and microstructure. These characteristics determine the long-term performance behaviour of the glass-ceramic wasteform in a geological disposal facility. The demand for increased waste loading per package, to minimise onward storage, management and disposal costs, results in a tendency towards liquid-liquid phase separation and (uncontrolled) crystallization of complex metal oxide phases. The grand challenge, to be addressed in this project, is in predictably achieving the targeted phase assemblage and microstructure, requiring a detailed understanding of the transformation process as a function of both cooling rate and melt chemistry. Controlling this phase separation and crystallization process is critical to preventing the formation of a non-durable crystal, glass, or crystal-glass interface. This understanding is of paramount importance for radioactive waste management programs in the UK, USA, and elsewhere, which seek to exploit glass-ceramic technology or, conversely, optimize conventional borosilicate glasses to improve the solubility of key fission products and actinides.
This research program is a joint collaborative enterprise between leading researchers from the US and UK who, collectively, bring mutually complementary and compatible skills, capabilities, and interests required to achieve a paradigm shift in the fundamental understanding of relevant phase separation and crystallization mechanisms in glass ceramics for radioactive waste immobilisation.

Planned Impact

The key beneficiaries who will gain from the research are:
1. Public and private sector organisations engaged in fuel cycle operation, will benefit directly from the knowledge and understanding generated by the research, which will assist in reducing the overall cost and hazard of radioactive waste management in future and legacy programmes.
2. The public will benefit from reduced future cost of civil nuclear energy generation and improved environmental outcomes as a result of more robust and holistic radioactive waste management strategies.
3. Policy makers will benefit from improved scientific underpinning of integrated fuel recycle and waste management strategies, which will assist in reducing uncertainties, leading to more accurate economic assessments.
4. The academic community will benefit from improved understanding of the molecular scale mechanisms and new experimental tools, to describe and characterise melt phase separation and crystallisation phenomena.
 
Description This project is focused primarily on understanding phase separation and crystallisation in glass-ceramic materials for the immobilisation of higher activity wastes from advanced nuclear fuel cycles, as part of a bilateral collaboration between the UK and USA. In these materials, molybdenum and zirconium are solubility limited elements, and hence the controlled partitioning of these species, into accessory crystalline phases, is considered key to increasing the incorporation rate of higher activity wastes. The project is still in progress, but already substantial progress has been made toward achieving objectives. The project has been supported by several bi-lateral visits between the partners in 2016-18.

The first phase of our research has investigated the crystallisation of CaMoO4 and Na2MoO4 from model borosilicate glasses, as a function of molybdenum and lanthanide concentration. State of the art multi-nuclear solid state NMR spectroscopy has been applied to understand the solubility mechanism of lanthanides and molybdenum in tandem and isolation. This knowledge guided the following phase of our research to control the crystallisation of the preferred CaMoO4 phase at the expense of Na2MoO4 (which has high aqueous solubility). Using NMR and X-ray absorption spectroscopies, we have demonstrated that crystallisation of Na2MoO4 can be avoided by controlling the role of alkali / alkaline earth cations in charge compensating non-bridging oxygens in the glass network. The first joint publication of research outcomes from this work was published as Patil et al., J. Nucl. Mater., 510 (2018) 539-550. Ultimately, this knowledge will be utilised to design a robust and reliable crystallisation schedule for waste canister cooling in a full scale application of this technology. The methods developed in this research have also been applied to understand the mechanisms of crystallisation in a family of novel vitusite glass-ceramics developed in an allied EPSRC sponsored project, published as Ceramics International, 43 (2017) 4687-4691. The international profile of our research in this and related projects, attracted the secondment of a PhD researcher to Sheffield, from the University of Hong Kong, to study crystallisation mechanisms of zirconia and zirconolite from complex aluminosilicate glasses. This research provided a new understanding of the controls of glass-ceramic composition and thermal history, in determining the crystallisation of zirconia and zirconolite phases from the parent glass, leading to a collaborative peer reviewed publication - Liao et al., Crystal Growth & Design, 17 (2017) 1079-1087. Building on this understanding, we can address the critical question of the influence of actinide speciation and concentration on crystallisation mechanisms, and partitioning between glass / ceramic phases, which is essential for application of these materials. This understanding was applied to investigate the thermal treatment of Prototype Fast Reactor raffinate, present on the Dounreay site, using a barium borosilicate glass matrix. This work successfully demonstrated the feasibility of PFR raffinate vitrification as a potential treatment option for this waste stream, with effective immobilisation of the radionuclide inventory in a glass matrix of superior durability to UK HLW glass compositions and, hence, suitable for interim storage and disposal; this work was published as Heath et al, J. Nucl, Mater., 508 (2018) 203-211.
Exploitation Route When matured, research could be taken up by national laboratories and government advisory bodies in designing and implementing flow sheets for immobilisation of higher activity wastes in future advanced fuel cycles.
Sectors Energy,Environment

 
Description This research, as part of a wider portfolio, part sponsored by UKRI, has further developed our understanding of how advanced waste treatment technologies can radically change the risk posed by the inventory of radioactive waste consigned to geological disposal, by eliminating waste reactivity, achieving effective immobilisation of long lived radionuclides, with substantial reduction in waste volume. This evidence was provided to the House of Commons Business, Energy and Industrial Strategy Committee on the Draft National Policy statement for Geological Disposal Infrastructure. The evidence was cited as the key basis for Recommendation 5 in the Committee report, "We recommend that the Government clarifies in the NPS the level of uncertainty regarding the inventory and explains to prospective host communities how this will affect their right to reject the GDI at any point during the siting process" - as set out at paragraph 34 in the body of the report.
First Year Of Impact 2018
Sector Energy,Environment,Government, Democracy and Justice,Manufacturing, including Industrial Biotechology
Impact Types Societal,Economic,Policy & public services

 
Description Impact on Draft National Policy Statement for Geological Disposal Infrastructure
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
Impact Written evidence to the House of Commons Business, Energy and Industrial Strategy Committee on the Draft National Policy statement for Geological Disposal Infrastructure, was cited as the key basis for Recommendation 5 "We recommend that the Government clarifies in the NPS the level of uncertainty regarding the inventory and explains to prospective host communities how this will affect their right to reject the GDI at any point during the siting process" - as set out at paragraph 34 in the body of the report.
URL https://publications.parliament.uk/pa/cm201719/cmselect/cmbeis/1092/1092.pdf
 
Description NIRAB II membership
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
 
Description A new precision cutting saw for radiological materials science
Amount £10,990 (GBP)
Organisation University of Sheffield 
Sector Academic/University
Country United Kingdom
Start 04/2016 
End 03/2017
 
Description DECC - MIDAS capital grant
Amount £800,000 (GBP)
Organisation Department of Energy and Climate Change 
Sector Public
Country United Kingdom
Start 04/2015 
End 03/2016
 
Description ERDF: Royce Translational Centre
Amount £4,005,654 (GBP)
Organisation European Commission 
Department European Regional Development Fund (ERDF)
Sector Public
Country European Union (EU)
Start 02/2018 
End 03/2019
 
Description NDA - Plutonium Disposition / IAA match
Amount £214,712 (GBP)
Organisation Nuclear Decommissioning Authority NDA 
Sector Public
Country United Kingdom
Start 12/2018 
End 03/2020
 
Description NDA Bursary Scheme - Brannerite glass ceramics
Amount £45,000 (GBP)
Organisation Nuclear Decommissioning Authority NDA 
Sector Public
Country United Kingdom
Start 09/2017 
End 09/2021
 
Description NDA Bursary Scheme - Plutonium surrogates
Amount £60,000 (GBP)
Organisation Nuclear Decommissioning Authority NDA 
Sector Public
Country United Kingdom
Start 09/2017 
End 09/2017
 
Description NDA Bursary Scheme - damaged fuels
Amount £60,000 (GBP)
Organisation Nuclear Decommissioning Authority NDA 
Sector Public
Country United Kingdom
Start 09/2017 
End 09/2021
 
Description Sir Henry Royce Institute - Sheffield Build
Amount £8,770,885 (GBP)
Funding ID EP/P025285/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 03/2016 
End 03/2019
 
Description Sir Henry Royce Institute -Sheffield Equipment
Amount £15,229,114 (GBP)
Funding ID EP/P02470X/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 03/2016 
End 03/2021
 
Description Thermal Treatment of Spent Ion Exchange Resins
Amount £25,010 (GBP)
Funding ID Award value is confidential 
Organisation Ministry of Defence (MOD) 
Sector Public
Country United Kingdom
Start 11/2018 
End 03/2020
 
Description US DOE - GLAD
Amount £232,000 (GBP)
Organisation U.S. Department of Energy 
Sector Public
Country United States
Start 01/2016 
End 01/2018
 
Description UoS & Suppliers - MIDAS equipment match
Amount £335,000 (GBP)
Organisation University of Sheffield 
Sector Academic/University
Country United Kingdom
Start 04/2015 
End 03/2016
 
Description Collaboration with ESRF XMAS and DUBBLE beamlines 
Organisation European Synchrotron Radiation Facility
Country European Union (EU) 
Sector Academic/University 
PI Contribution Extended application focus of beamline techniques to XAS data acquistion in the hard X-ray regime.
Collaborator Contribution Beamline optimisation to acquire XAS data from glass and ceramic materials in support of plutonium disposition.
Impact See publications section.
Start Year 2016
 
Description Collaboration with The University of Hong Kong 
Organisation University of Hong Kong
Department Department of Microbiology
Country Hong Kong 
Sector Academic/University 
PI Contribution Application of TEM and electron diffraction methods to characterisation of zirconolite crystallisation in glass-ceramic materials.
Collaborator Contribution Application of TEM and electron diffraction methods to characterisation of zirconolite crystallisation in glass-ceramic materials.
Impact See publications section.
Start Year 2016
 
Description DELTA (Dortmunder ELekTronenspeicherring-Anlage) 
Organisation Technical University of Dortmund
Department Dortmund Electron Storage Ring System (DELTA)
Country Germany 
Sector Academic/University 
PI Contribution Development of beamline XAS applications to low concentration detection in disordered systems and expansion of international user programme.
Collaborator Contribution Acquisition of XAS data in hard X-ray regime.
Impact See publications section.
Start Year 2016
 
Description PNNL 
Organisation U.S. Department of Energy
Department Pacific Northwest National Laboratory
Country United States 
Sector Public 
PI Contribution Investigation and understanding of phase separation and crystallisation in glass-ceramics for immobilisation of high level radioactive waste from future fuel cycles.
Collaborator Contribution Investigation and understanding of phase separation and crystallisation in glass-ceramics for immobilisation of high level radioactive waste from future fuel cycles.
Impact See publications section.
Start Year 2015
 
Description Rutgers University 
Organisation Rutgers University
Department Materials Science and Engineering
Country United States 
Sector Academic/University 
PI Contribution Investigation and understanding of phase separation and crystallisation in glass-ceramics for immobilisation of high level radioactive waste from future fuel cycles.
Collaborator Contribution Investigation and understanding of phase separation and crystallisation in glass-ceramics for immobilisation of high level radioactive waste from future fuel cycles.
Impact See publication section.
Start Year 2015
 
Description Washington State University at Pullman 
Organisation Washington State University
Country United States 
Sector Academic/University 
PI Contribution Investigation and understanding of phase separation and crystallisation in glass-ceramics for immobilisation of high level radioactive waste from future fuel cycles.
Collaborator Contribution Investigation and understanding of phase separation and crystallisation in glass-ceramics for immobilisation of high level radioactive waste from future fuel cycles.
Impact See publications section.
Start Year 2015
 
Description IAEA Summer School on Radiation Effects on Radioactive Wasteforms 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Organised Joint ICTP-IAEA Workshop on Radiation Effects in Nuclear Waste Forms and their Consequences for Storage and Disposal, 12-16 September 2016, with engagement of over 30 international researchers.
Year(s) Of Engagement Activity 2017
URL http://indico.ictp.it/event/7633/
 
Description IAEA Workshop on Management Strategies for Separated Plutonium 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Expert workshop to identify and assess options for managing separated plutonium stockpiles, the presentations and discussion will input into an IAEA Technical Document.
Year(s) Of Engagement Activity 2018
 
Description International Plutonium Pathways Workshop 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact International workshop to assess the current status of plutonium management strategy internationally. Presentation and discussion will input into expert summary report to be published by Federation of American Scientists.
Year(s) Of Engagement Activity 2018
 
Description Interview with BBC Radio Cumbria 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Media (as a channel to the public)
Results and Impact Prof. Neil Hyatt was interviewed live on BBC Radio Cumbria, discussing the end of nuclear fuel reprocessing operations at THORP and Sellafield decommissioning challenges.
Year(s) Of Engagement Activity 2019
 
Description Interview with Daily Mail newspaper: GDF siting 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact Interview with Daily Mail newspaper on launch of siting process for UK Geological Disposal Facility for radioactive waste.
Year(s) Of Engagement Activity 2018
 
Description MRS Scientific Basis for Nuclear Waste Management XL 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Organised flagship 40th anniversary MRS symposium on scientific basis for nuclear waste management, showcasing research in multiple EPSRC sponsored projects.
Year(s) Of Engagement Activity 2017
 
Description Media and public engagement workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact Delivered a media and public engagement skills summer school for postgraduate and postdoctoral researchers in DISTINCTIVE consortium, which was open to attendance to EPSRC sponsored researchers in nuclear energy.
Year(s) Of Engagement Activity 2016
 
Description New Scientist Interview: SMRs 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview on potential for advanced modular reactor technology for New Scientist magazine.
Year(s) Of Engagement Activity 2018
 
Description Organised: MRS Scientific Basis for Nuclear Waste Management Symposium, 2018 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Organised the MRS Scientific Basis for Nuclear Waste Management Symposium, 2018, which attracted more than 100 experts from around the world for a 4 day symposium on state of the art research outcomes in the field.
Year(s) Of Engagement Activity 2018
 
Description Participation in International Glass Working Group 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Participation in International Glass Working Group - dissemination of research outcomes from multiple EPSRC sponsored projects with the aim of developing a state of the art unified model for glass corrosion, relevant to radioactive waste disposal; participation in expert group designing collaborative international experiments using International Standard Glass.
Year(s) Of Engagement Activity 2017
 
Description Sheffield scientists pioneer new method for managing radioactive waste 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Television interview as part of World Science day, discussing radioactive waste management research associated with EPSRC sponsored projects.
Year(s) Of Engagement Activity 2017
URL https://vimeo.com/191056195