UNIGRAF: Understanding and improving graphite for nuclear fission
Lead Research Organisation:
University of Bristol
Department Name: Interface Analysis Centre
Abstract
Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.
Publications
Liu D
(2017)
Towards understanding the influence of porosity on mechanical and fracture behaviour of quasi-brittle materials: experiments and modelling.
in International journal of fracture
Liu D
(2017)
On the damage and fracture of nuclear graphite at multiple length-scales
in Journal of Nuclear Materials
Liu D
(2017)
Deformation and fracture of carbonaceous materials using in situ micro-mechanical testing
in Carbon
März B
(2018)
Near-surface structure and residual stress in as-machined synthetic graphite
in Materials & Design
Šavija B
(2019)
Modelling of deformation and fracture for a model quasi-brittle material with controlled porosity: Synthetic versus real microstructure
in Engineering Fracture Mechanics
Šavija B
(2018)
Modelling deformation and fracture of Gilsocarbon graphite subject to service environments
in Journal of Nuclear Materials
Šavija B
(2016)
Experimentally informed multi-scale modelling of mechanical properties of quasi-brittle nuclear graphite
in Engineering Fracture Mechanics
| Description | 1. Assisted with the interpretation of service-acquired and test reactor-acquired X-ray diffraction data for AGR reactor core graphite. This is enabling both novel interpretation and understanding for evaluating long-term integrity. 2. Microstructure-based FE modeling has successfully predicted the role of both neutron damage and CO2 oxidation on the deformation and fracture of AGR reactor core graphite. These data have been made available to EDF energy as a basis for improved understanding and inputs into their safety cases. Contributed to Case Study for the current Bristol REF submission. |
| Sector | Energy |
| Impact Types | Economic |
| Description | Graphite X-ray diffraction data analysis , Phase 1 |
| Amount | £40,000 (GBP) |
| Funding ID | 4840479529 |
| Organisation | EDF Energy |
| Sector | Private |
| Country | United Kingdom |
| Start | 01/2017 |
| End | 08/2017 |
| Description | Modelling at the test specimen length-scale deformation and fracture of unirradiated and irradiated Gilsocarbon graphite |
| Amount | £30,000 (GBP) |
| Organisation | EDF Energy |
| Sector | Private |
| Country | United Kingdom |
| Start | 02/2016 |
| End | 10/2016 |
| Description | Modelling the deformation and fracture of irradiated Gilsocarbon graphite |
| Amount | £27,000 (GBP) |
| Organisation | EDF Energy |
| Sector | Private |
| Country | United Kingdom |
| Start | 09/2015 |
| End | 01/2016 |
| Title | Resistivity measurement under load and temperature of graphite |
| Description | Measurement of resistivity of tensile test specimens over a temperature range developed in conjunction with Dr Bryan Roebuck at NPL |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2017 |
| Provided To Others? | No |
| Impact | Provides new insights on the fracture and deformation of reactor core type graphite |
| Title | Microstructural based FE model developed and applied in conjunction with Profressor E Schlangen Technical University of Delft |
| Description | Model has been applied to predict the deformation and fracture properties of un- and irradiated reactor core graphite and will be applied to the Sinosteelgraphite used in the current project [ |
| Type Of Material | Computer model/algorithm |
| Year Produced | 2016 |
| Provided To Others? | Yes |
| Impact | Allows prediction of properties of reactor core graphite when subject to service environment....temperature , neutron dose and oxidizing environment |
| Description | Graphite X-Ray Diffraction Data Analysis |
| Organisation | EDF Energy |
| Department | EDF Energy Nuclear Generation |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | ABSTRACT Dr Mark Bradford (EDF Energy) provided examples of x-ray diffraction data acquired from specimens of Gilsocarbon graphite in unirradiated and irradiated conditions. These have been subject to different temperatures and neutron doses. A preliminary evaluation was undertaken of these data to establish if there was the potential to determine the macro-strain (stress), micro-strain (stress) and crystallite size. The analyses, including application of the procedure described by Williamson and Hall, indicated that it may be possible to evaluate these parameters from a detailed consideration of x-ray diffraction (XRD) peak position, peak shape and width. CONCLUSIONS A preliminary examination of the x-ray diffraction 2? traces has been undertaken to further address changes that arise in the Gilsocarbon graphite when subject to neutron irradiation. The approach has centred on application of the Williamson-Hall method to allow separation of coherence length (crystallite size) and micro-strain. Within the constraints when this method is adopted, the measured changes with increasing neutron irradiation include: • An expansion of the c lattice parameter. • A reduction in the a lattice parameter. • A reduction in average coherence length (crystallite size). • An increase in compressive micro-strain. However, to implement this analysis required assumptions relating to individual peak profiles and omission of the 101 diffraction peak. As a consequence, there is a need to provide a rationale for both of these assumptions, which can be linked to the complex atomic structure of the graphite. RECOMMENDATIONS The work described in this report meets the contract specification to provide a preliminary evaluation of specimens selected for the Blackstone programme. Both unirradiated and neutron-irradiated x-ray diffraction 2? traces have been further analysed. This demonstrates that it is possible to obtain a measure of coherence length (crystallite size) and micro-strain using the Williamson-Hall procedure. However, in order to implement the procedure assumptions have been required to achieve realistic measurements. The analyses have identified that there is more information embedded in these x-ray diffraction traces that can be further interrogated. Hence, as a minimum the following could be rigorously revisited: • A detailed analysis of specific peak profiles, such as the 002. • Overlap of the 100 and 101 diffraction peaks, their origin and the basis for exclusion of the 101 peak from the Williamson-Hall analyses. One potential interpretation of the overlap is that it is a result of complex interactions between hexagonal graphite and the turbostratic structure. • Further exploration of the correlation between the atomic-scale structure in both unirradiated and irradiated graphite, and the resultant x-ray diffraction traces. To achieve this requires a consideration of atomic-scale model predictions and the associated impact on the specific diffraction peak positions and profiles. Certainly, there is a need to deconvolute contributions from neutron dose, temperature and mass loss if appropriate data are available. |
| Collaborator Contribution | Supplied data. |
| Impact | Oral presentation at the 6th EDF Graphite Conference, 15-18 October 2018, Kendal, UK: Analyses of X-Ray Diffraction Data Obtained from Unirradiated and Irradiated Gilsocarbon Graphite James E Darnbrough1,†, Keith R Hallam1, Peter EJ Flewitt1, Mark R Bradford2 1University of Bristol, Interface Analysis Centre, School of Physics, Tyndall Avenue, Bristol, BS8 1TL 2EDF Energy, Barnett Way, Barnwood, Gloucester, GL4 3RS †Current address: University of Oxford, Department of Materials, Parks Road, Oxford, OX1 3PH Journal paper in preparation: The nano-structure of unirradiated and irradiated synthetic graphite James E Darnbrough1,†, Keith R Hallam1, Peter EJ Flewitt1*, Mark R Bradford2 1University of Bristol, Interface Analysis Centre, School of Physics, Tyndall Avenue, Bristol, BS8 1TL 2EDF Energy, Barnett Way, Barnwood, Gloucester, GL4 3RS †Current address: University of Oxford, Department of Materials, Parks Road, Oxford, OX1 3PH |
| Start Year | 2016 |
| Description | Project progress meetings |
| Organisation | EDF Energy |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Technical advice |
| Collaborator Contribution | Plant knowledge |
| Impact | Ongoing |
| Start Year | 2016 |
| Description | Graphite Core Committee (EDF Energy, UK) |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Industry/Business |
| Results and Impact | Specialist expert group. |
| Year(s) Of Engagement Activity | 2015,2016,2017 |
| Description | Vice-Chair (Nuclear), Energy of Materials Group, IoM3 |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | -- |
| Year(s) Of Engagement Activity | 2015,2016,2017,2018 |