The Development of Advanced Technologies and Modelling Capabilities to Improve the Safety and Performance of Nuclear Fuel

Lead Research Organisation: University of Manchester
Department Name: Mechanical Aerospace and Civil Eng

Abstract

The main factors that limit the performance of nuclear fuels are related to cladding failure due to interactions with the fuel pellet and reactor coolant. Improvements to our understanding of the cladding failure mechanisms will enhance our ability to predict their effects, leading both to improvements in the safety and operation of current fuels, and to technological developments that will produce improved fuel, cladding, and coating materials. The research tasks below seek to address each of these issues in turn, from the perspective of both current and advanced fuel designs.Aomistic modelling research will focus on the input that atomic scale simulations make in describing the behaviour of micro-structural defects. This will refine our understanding of the fundamental physical processes that degrade fuel performance, and will result in improvements to current semi-empirical fuel performance models. The simulations will focus upon the interaction of fission products, radiation damage and dislocations, processes responsible for macroscopic observables such as fission gas release and irradiation induced creep.Fuel and cladding dimensional changes resulting from thermo-mechanical and irradiation conditions produce complex pellet-clad mechanical interactions (PCMI) that are known to cause fuel failure, especially under accident conditions. Models for PCMI failure based on ramp-test data have been developed, but these are highly empirical and therefore of limited applicability. However, advances in finite element (FE) modelling now permit the development of detailed models, and techniques such as the extended FE method can be applied to model crack growth and crack tip stresses and strains accurately whilst taking into account residual and applied stress redistribution. This research will investigate the development of pellet crack patterns and pellet-clad interface stresses under both normal and off-normal conditions. Mechanistic models for pellet failure and cladding damage will be developed.Research into composite cladding will investigate the potential for silicon carbide composites to provide significantly better performance compared with existing cladding materials. A new approach will be investigated, based on a solid SiC inner tube wrapped with SiC fibers and bonded using SiC vapour infiltration. The research will address fundamental aspects of this new concept, including: characterisation of the relationship between both design and manufacturing parameters and mechanical strength; ability of the tube to remain impermeable against fission products; and resistance to oxidation and fission product attack at high temperatures. Although UO2 has been used for many years as a fuel material, promising new materials have ben developed that could offer advantages in terms of safety and performance. The objective of this research is to identify alternative fuel materials and fuel forms; to evaluate their physical properties such as thermal conductivity; assess their reactivity with water using autoclave testing; and to assess industrially-feasible manufacturing routes. Candidate materials include alloys such as U3Si2, U-Mo, U-Zr and covalent compounds such as carbides and nitrides (in the latter case with additives to reduce the reaction rate in water). TRISO coated fuel particles manufactured by chemical vapour deposition (CVD) have demonstrated remarkable performance, but are known to be susceptible to attack by fission products such as Pa. This research will provide a fundamental understanding of these issues and will investigate alternative materials and processes to provide improved performance. The high temperature mechanical properties of coatings will be examined to understand the effects of manufacturing conditions. The mechanisms of fission product transport will be studied with a view to introducing materials and microstructural changes that will improve performance in this respect.

Planned Impact

Private sector beneficiaries of the research will include designers and suppliers of nuclear fuels; suppliers of intermediary products such as fuel cladding and components; providers of specialist licensing services such as consultancy groups; and operators of nuclear power plants. In the longer term, improvements in coated particle technology will assist implementation of the HTR system, that can supply high temperature heat to a range of industries. All of the proposed research is linked with improvements in the performance and safety of nuclear fuel, which is expected to translate directly into reduced risk, providing a direct benefit to the public. The nuclear regulator will also benefit from access to improved fundamental understanding and modelling methods. The private sector will benefit through improvements in the competitiveness of the products that can be manufactured at the UK's nuclear fuel fabrication facility at Springfields, which will also benefit the supply chain for this business. Specialist consulting organisations will benefit from the analysis that will be required to validate and license any potential new fuel products that arise as a result of the proposed work. Nuclear power plant operators will benefit from improvements to the fuel product capabilities (by extending fuel lifetimes and reducing failure rates, for example), and also from improvements in fundamental understanding of life-limiting phenomena, which will allow better fuel models to be developed, potentially enhancing operational flexibility. The public will benefit from improvements in fuel capability and hence improved safety margins, and may also realise some economic benefit flowing from improvements in plant operations. The proposed work will also enhance the capability of UK academia and result in the training of young researchers who would be of immediate value to both private industry and public sctor bodies. Both Universities have excellent relationships with the nuclear industry and public bodies associated with nuclear energy in the UK. Agreements are in place with a majority of the UK's key nuclear industry and public sector organisations (EDF, British Energy, Westinghouse, Rolls-Royce, National Nuclear Lab, AMEC, Serco, etc.), and many of these have been involved in formulating the proposed research. Accordingly, robust arrangements are already in place for industry collaboration in the proposed research, as evidenced by the attached letters of support for the proposal, and channels for dissemination of the research results are already well established. Engagement will be ensured by working closely with the partner organisations, and providing opportunities for researchers to spend periods of time working with industry partners. The results of the research will be disseminated both at industry-focussed events such as workshops, and at wider events such as seminars. The partners will establish a web-site to engage a wider audience in the outcomes of the research activities, and will utilise their respective public affairs departments to ensure that the research is afforded a high visibility within their respective nuclear-focussed activities. As mentioned, both Universities have extensive collaborative links with private and public sector organisations, including other Universities in the UK and overseas. Both have collaborated together in previous and current EPSRC programmes such as KNOO and DIAMOND. The UK nuclear industry is well placed to exploit the benefits from the proposed research. Both Universities have established mechanisms for ensuring that the benefits of academic research are properly exploited and protected. Impact activities will be co-ordinated by the PI, but undertaken by all academic staff involved as appropriate, and the partners will benefit from the advice and involvement of Dr John Roberts, the External Liason Manager at the Dalton Nuclear Institute.

Publications

10 25 50

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Gentile M (2015) Palladium interaction with silicon carbide in Journal of Nuclear Materials

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Turner J (2013) The thermal performance of fuel matrix material in a CO2 atmosphere in Journal of Nuclear Materials

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Mella R (2015) Modelling explicit fracture of nuclear fuel pellets using peridynamics in Journal of Nuclear Materials

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Murphy S (2015) Xe diffusion and bubble nucleation around edge dislocations in UO 2 in Journal of Nuclear Materials

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Murphy S (2014) Pipe diffusion at dislocations in UO2 in Journal of Nuclear Materials

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Cooper MW (2014) A many-body potential approach to modelling the thermomechanical properties of actinide oxides. in Journal of physics. Condensed matter : an Institute of Physics journal

 
Description The research has allowed us to identify promising approaches to the development of new nuclear fuel and cladding materials that offer significant advantages in respect of performance under normal operating conditions, and especially under fault conditions where fuel cooling has been compromised. We have also made significant advances in our understanding of the performance of advanced TRISO coated particle fuels, and in particular the relationships between manufacturing conditions, fuel microstructure, and subsequent in-reactor performance. Finally, we have made considerable advances in our ability to apply molecular dynamics modelling to accurately predict the properties of materials that have not yet been manufactured. This will be invaluable in assessing a very broad range of candidate materials prior to committing experimental resources.
Exploitation Route Our findings will be taken forward in the frame of the EPSRC-funded PACIFIC project, and in the frame of additional academic and national laboratory research recommended by NIRAB. The research also has the potential to be utilised by our industrial partners Westinghouse, Rolls-Royce, and NNL.
Sectors Energy

 
Description The findings on materials properties for a range of novel fuel compounds have been used within the collaboration to identify promising new fuel materials. Some of our results have already been used by our industry partners (Westinghouse and Rolls-Royce) to identify ways to improve the performance of existing and new fuel products. Specific examples include potential composite fuel materials, such as UO2 with additions such as Mo, and SiC-SiC ceramic cladding materials that offer significantly improved accident performance compared with current Zr-based cladding alloys. The results have also fed directly into the elaboration of UK research policy, via the recommendations of the Government's Nuclear Innovation and Research Advisory Board (NIRAB) in late 2016.
First Year Of Impact 2014
Sector Energy,Manufacturing, including Industrial Biotechology
Impact Types Economic,Policy & public services

 
Description Participation in NIRAB by Prof. Abram, Prof. Lees, and Prof. Grimes
Geographic Reach National 
Policy Influence Type Membership of a guidance committee
Impact The research that is being recommended by NIRAB will be important in improving the safety and economic performance of current and future UK nuclear power facilities, as well as UK environmental impacts and UK education and training.
 
Description Review of Nuclear Fuel Technology for Future UK Research Needs, delivered to DECC
Geographic Reach National 
Policy Influence Type Citation in other policy documents
Impact The NNL/Manchester reports have influenced the development of nuclear research policy within DECC and BIS, and this will have significant impacts on UK economic activities and on research/training/education in nuclear technology.
 
Description German Academic Exchange Service Travel Award
Amount € 8,000 (EUR)
Organisation German Academic Exchange Service (DAAD) 
Sector Public
Country United States
Start 09/2013 
End 05/2014
 
Description Nuclear Fuel Centre of Excellence
Amount £8,000,000 (GBP)
Organisation Department for Business, Energy & Industrial Strategy 
Sector Public
Country United Kingdom
Start 12/2013 
End 03/2014
 
Title Laser-based ceramic joining technology 
Description A laser-based technique for joining ceramic nuclear fuel components using ceramic brazing has been developed. This can be applied to investigate the production of advanced ceramic fuel claddings that offer significantly greater temperature capabilities compared with existing Zr-alloy claddings. 
Type Of Material Technology assay or reagent 
Provided To Others? No  
Impact The ability to join silicon carbide composite materials offers the possibility of utilising the material to produce fuel rod claddings with very high temperature capabilities. This could provide a large improvement in safety compared with existing metallic cladding materials. The joining capability will enable a range of potential ceramic brazing compounds to be explored, in order to identify compounds that are capable of surviving inside the core of an operating reactor. The University of Manchester, in collaboration with Rolls-Royce, is pursuing a patent for this technique. 
 
Title Molecular Dynamics modelling of advanced actinide oxides 
Description Molecular dynamics techniques have been extended to allow the prediction of fundamental properties such as thermal conductivity for a range of actinide oxides. 
Type Of Material Model of mechanisms or symptoms - in vitro 
Year Produced 2011 
Provided To Others? Yes  
Impact The modelling techniques allow the identification of promising fuel materials in advance of experimental preparation and determination of thermo-physical properties. This will result in a more efficient identification of promising new materials, saving experimental time and effort. 
 
Title Preparation of TRISO particles with ZrC coatings 
Description A new capability to produce TRISO coated fuel particles with a ZrC coating has been developed and installed at Manchester. This utilises existing expertise in the production of SiC-coated particles, but extends the capability to develop fuels with a higher temperature capability. 
Type Of Material Technology assay or reagent 
Provided To Others? No  
Impact This will facilitate current research conducted in the frame of EPSRC and European programmes, as well as offering an important new opportunity to conduct further research into Generation-IV fuels in support of the new NIRAB research recommendations for the UK. 
 
Description Collaboration with NNL, Westinghouse, and Rolls-Royce 
Organisation National Nuclear Laboratory
Country United Kingdom 
Sector Public 
PI Contribution Manchester, NNL, and Westinghouse have jointly contributed to developing a research vision for nuclear fuel in the UK. Manchester and NNL have developed this into a technology review and research plan that has been submitted to DECC, partly via the Government's new Nuclear Innovation and Research Advisory Board (NIRAB). Manchester and NNL have also developed a proposal to Government to establish a new Nuclear Fuel Centre of Excellence (NFCE) for the UK. This proposal has been submitted to BIS, and this has resulted in the award of a grant of £8m to NNL and Manchester to establish a new suite of research facilities. These were officially launched on 13 October 2014. Subsequently, NNL and Manchester submitted proposals to DECC to establish an Accident Tolerant Fuels capability within the NFCE. This resulted in the award of £1.5m to NNL and £1m to Manchester in April 2015. These facilities are of major importance to EPSRC-funded research projects such as PACIFIC.
Collaborator Contribution Imperial College have contributed to the development and review of the UK's future nuclear fuel research programme, not least through the contributions of Prof. Robin Grimes and Prof. Bill Lee through their role on NIRAB.
Impact In addition to the outcomes listed above, experts from NNL and Westinghouse have assisted in reviewing and guiding the research outcomes. NNL have also assisted in offering training and safety advice to researchers in the collaboration.
Start Year 2009
 
Description Collaboration with NNL, Westinghouse, and Rolls-Royce 
Organisation Rolls Royce Group Plc
Country United Kingdom 
Sector Private 
PI Contribution Manchester, NNL, and Westinghouse have jointly contributed to developing a research vision for nuclear fuel in the UK. Manchester and NNL have developed this into a technology review and research plan that has been submitted to DECC, partly via the Government's new Nuclear Innovation and Research Advisory Board (NIRAB). Manchester and NNL have also developed a proposal to Government to establish a new Nuclear Fuel Centre of Excellence (NFCE) for the UK. This proposal has been submitted to BIS, and this has resulted in the award of a grant of £8m to NNL and Manchester to establish a new suite of research facilities. These were officially launched on 13 October 2014. Subsequently, NNL and Manchester submitted proposals to DECC to establish an Accident Tolerant Fuels capability within the NFCE. This resulted in the award of £1.5m to NNL and £1m to Manchester in April 2015. These facilities are of major importance to EPSRC-funded research projects such as PACIFIC.
Collaborator Contribution Imperial College have contributed to the development and review of the UK's future nuclear fuel research programme, not least through the contributions of Prof. Robin Grimes and Prof. Bill Lee through their role on NIRAB.
Impact In addition to the outcomes listed above, experts from NNL and Westinghouse have assisted in reviewing and guiding the research outcomes. NNL have also assisted in offering training and safety advice to researchers in the collaboration.
Start Year 2009
 
Description Collaboration with NNL, Westinghouse, and Rolls-Royce 
Organisation Westinghouse
Country United States 
Sector Private 
PI Contribution Manchester, NNL, and Westinghouse have jointly contributed to developing a research vision for nuclear fuel in the UK. Manchester and NNL have developed this into a technology review and research plan that has been submitted to DECC, partly via the Government's new Nuclear Innovation and Research Advisory Board (NIRAB). Manchester and NNL have also developed a proposal to Government to establish a new Nuclear Fuel Centre of Excellence (NFCE) for the UK. This proposal has been submitted to BIS, and this has resulted in the award of a grant of £8m to NNL and Manchester to establish a new suite of research facilities. These were officially launched on 13 October 2014. Subsequently, NNL and Manchester submitted proposals to DECC to establish an Accident Tolerant Fuels capability within the NFCE. This resulted in the award of £1.5m to NNL and £1m to Manchester in April 2015. These facilities are of major importance to EPSRC-funded research projects such as PACIFIC.
Collaborator Contribution Imperial College have contributed to the development and review of the UK's future nuclear fuel research programme, not least through the contributions of Prof. Robin Grimes and Prof. Bill Lee through their role on NIRAB.
Impact In addition to the outcomes listed above, experts from NNL and Westinghouse have assisted in reviewing and guiding the research outcomes. NNL have also assisted in offering training and safety advice to researchers in the collaboration.
Start Year 2009
 
Description Annual talk to Cumbria IMechE 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact The talks always stimulate engaging discussions amongst practising engineers.

Several attendees remain in regular contact and follow the development of research outcomes.
Year(s) Of Engagement Activity 2009,2010,2011,2012,2013
 
Description Presentation to Edinburgh International Science Festival 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact The talk was followed by an open discussion session that stimulated a long and engaging dialogue with members of the public concerning advances in nuclear fuel technology and the ways in which these could be applied to improve safety and economic benefits.

Several members of the public continued to engage by email etc. and continued to engage with research activities undertaken by the academic partners engaged in this grant.
Year(s) Of Engagement Activity 2013
 
Description Smallpeice Trust Talks 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Schools
Results and Impact Provided a talk on outcomes of nuclear fuel research and to demonstrate how this can impact on the safety and economics of nuclear power.

Several students continue to engage via email after the talks, and some have remained in contact subsequently.
Year(s) Of Engagement Activity 2010,2011,2012,2013,2014