Degradation of the thermal and mechanical properties SiCf/SiCm composite with irradiation

Lead Research Organisation: University of Bristol
Department Name: Physics

Abstract

An exciting opportunity to contribute to the application of SiC-based ceramic matrix composites in nuclear fission and its translation to fusion. For this project the MSE-F group (UKAEA) will supply four different grades of SiCf/SiCm available from international industrial partners. The PhD student on this project will be based at the University of Bristol and is anticipated to spend a significant amount of time at UKAEA to conduct relevant experiments, such as micromechanical testing and Focus Ion Beam tomography characterisation.
Materials able to operate at extreme temperatures, resisting high-flux neutron irradiation damage while remaining structurally stable are needed for components in nuclear fission, e.g., as accident tolerant fuel cladding, as well as nuclear fusion including STEP (Spherical Tokamak for Energy Production) and DEMO. In particular, it has been recognised that silicon-carbide (SiC) fibre reinforced SiC matrix composites (SiCf/SiCm), which has low neutron absorption, high thermal conductivity, high fracture toughness, excellent chemical/mechanical stability at elevated temperatures (e.g., ~1000C), are able to provide the highest thermodynamic efficiency nuclear structural components.
During this project, the PhD student will first conduct a review regarding the available irradiation data in open literature for this class of materials, and design subsequent irradiation experiments using energetic ions, protons or neutrons. The irradiated samples will be examined in terms of their micro-mechanical properties, depends on the thickness of the surface irradiated layer, conventional nano-indentation or more sophisticated micro-cantilever bending/pillar compression tests will be conducted. The thermal conductivity degradation of the SiC fibre and matrix, which is a function of the irradiation damage, will be measured using high-resolution TTR (transient thermoreflectance) method which is unique in the UK where Bristol has about 20 years' experience.
In addition, a unique in situ high temperature X-ray micro-tomography technique will be used to investigate the deformation and fracture of unirradiated SiCf/SiCm. This will study only the effect of service temperature on the material's mechanical behaviour in terms of strength/failure strain, crack initiation and propagation when loaded under conditions similar to service.

Planned Impact

It cannot be overstated how important reducing CO2 emissions are in both electricity production for homes and industry but also in reducing road pollution by replacing petrol/diesel cars with electric cars in the next 20 years. These ambitions will require a large growth in electricity production from low carbon sources that are both reliable and secure and must include nuclear power in this energy mix. Such a future will empower the vision of a prosperous, secure nation with clean energy. To do this the UK needs more than 100 PhD level people per year to enter the nuclear industry. This CDT will impact this vision by producing 70, or more, both highly and broadly trained scientists and engineers, in nuclear power technologies, capable of leading the UK new build and decommissioning programmes for future decades. These students will have experience of international nuclear facilities e.g. ANSTO, ICN Pitesti, Oak Ridge, Mol, as well as a UK wide perspective that covers aspects of nuclear from its history, economics, policy, safety and regulation together with the technical understanding of reactor physics, thermal hydraulics, materials, fuel cycle, waste and decommissioning and new reactor designs. These individuals will have the skill set to lead the industry forward and make the UK competitive in a global new build market worth an estimated £1.2tn. Equally important is reducing the costs of future UK projects e.g. Wylfa, Sizewell C by 30%, to allow the industry and new build programme to grow, which will be worth £75bn domestically and employ tens of thousands per project.

We will deliver a series of bespoke training courses, including on-line e-learning courses, in Nuclear Fuel Cycle, Waste and Decommissioning; Policy and Regulation; Nuclear Safety Management; Materials for Reactor Systems, Innovation in Nuclear Technology; Reactor Operation and Design and Responsible Research. These courses can be used more widely than just the CDT educating students in other CDTs with a need for nuclear skills, other university courses related to nuclear energy and possibly for industry as continual professional development courses and will impact the proposed Level 8 Apprenticeship schemes the nuclear industry are pursuing to fill the high level skills gap.

The CDT will deliver world-class research in a broad field of nuclear disciplines and disseminate this work through outreach to the public and media, international conferences, published journal articles and conference proceedings. It will produce patents where appropriate and deliver impact through start-up companies, aided by Imperial Innovations, who have a track record of turning research ideas into real solutions. By working and listening to industry, and through the close relationships supervisory staff have with industrial counterparts, we can deliver projects that directly impact on the business of the sponsors and their research strategies. There is already a track record of this in the current CDT in both fission and fusion fields. For example there is a student (Richard Pearson) helping Tokamak Energy engage with new technologies as part of his PhD in the ICO CDT and as a result Tokamak Energy are offering the new CDT up to 5 studentships.

Another impact we expect is an increasing number of female students in the CDT who will impact the industry as future leaders to help the nuclear sector reach its target of 40% by 2030.
The last major impact of the CDT will be in its broadening scope from the previous CDT. The nuclear industry needs to embrace innovation in areas such as big data analytics and robotics to help it meet its cost reduction targets and the CDT will help the industry engage with these areas e.g. through the Bristol robotics hub or Big Data Institute at Imperial.

All this will be delivered at a remarkable value to both government and the industry with direct funding from industry matching the levels of investment from EPSRC.

Publications

10 25 50

Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S023844/1 31/03/2019 29/09/2027
2764488 Studentship EP/S023844/1 30/09/2022 29/09/2026 Daniel Cogbill