Investigating the Effects of Microstructure on Irradiation Damage in Fusion-Specific Ceramics – Materials Strand Project

Supervisors: Professor Tinka Marquardt (Lead) and Professor David Armstrong (University of Oxford).

For fusion to be a commercial reality it will require fuel, most likely in the form of deuterium and tritium. Whilst deuterium is readily available there is no supply chain for tritium in the quantities that will be required, due to its 13 year half life. All commercial devices will be required to be self-sufficient in tritium breeding after start up. This has never been demonstrated as feasible. Lithium containing ceramics are the leading candidate for breeding, having been developed for ITER and identified as the leading solution for  STEP tritium production and are under active consideration by multiple other commercial entities.  However little work has been done to assess the effect of lithium burn up and radiation damage on their mechanical properties, especially on the newer material such as those being developed by Oxford University. Ceramics will also find use as neutron shielding materials, most likely in the form of Tungsten carbide or borides, used to protect the magnets from neutron damage.

The deployment of ceramic materials in components promises to achieve the demanding requirements associated with commercial power plant design. As fusion enters its ‘delivery era’, there is a need for greater understanding of materials degradation in-service to continue the progress of power plant design maturity.

The focus will be on two key ceramic systems:

• Breeder ceramics such as lithium metatitanate
• Shielding ceramics such as tungsten carbide

The focus on two different system derisks the project as if one class of materials is deselected from industrial designs the student can focus on the other. Fundamental understandings of these systems will be useful to underpin fundamental understanding of ceramic material degradation.

The lithium breeder ceramics will be irradiated with heavy ions to simulate knock on damage and helium to simulate the alpha particle production during the tritium production. The focus will then on understanding how the microstructure controls the accumulation of radiation damage defects in the ceramics, followed by how this effects the mechanical behaviour. This will be conducted using micromechanical testing methods developed in Oxford and already applied to other ceramics such as SiC. By using different processing routes (direct sintering, Sol Gel, SPS) different grain boundary distributions will be produced and characterised using TEM. Understanding this link between microstructure, radiation damage and mechanical properties is vital information for robust and economical breeder blanket design.

Key Outcomes:

• Improved understanding of irradiation-induced degradation in fusion relevant ceramics
• Identification of microstructural features that enhance performance
• Development of characterisation and benchmarking techniques for fusion materials
• Contribution to UKAEA’s strategic goals in materials qualification and reactor design.

During the first six months of the PhD, materials strand students will typically travel to attend taught modules at all six of the Fusion CDT partner universities.

The project will be mainly based in Oxford, but there is the opportunity for travel to conferences and collaborations with other groups.

This project is offered by University of Oxford. For further information please contact: David Armstrong (david.armstrong@materials.ox.ac.uk).

This project may be compatible with part time study, please contact the project supervisors if you are interested in exploring this.

For details on how to apply, please visit: Apply