IMX Colloquium - Materials Degradation When Fuelling a Tokamak

For any commercial Fusion device to operate it will require a source of tritium to be bred within the device using the neutrons generated in the D-T reaction. This can only be done through the neutron capture of a neutron by a lithium-6 nucleus. Different power plant concepts are looking to have the lithium held in different forms; two of the most common are either liquid lithium or solid lithium ceramics.
In this talk I will discuss some of the material science and engineering challenges associated with tritium breeding. This will start with the corrosion of structural materials by liquid lithium and show that steels in particular are highly susceptible to lithium corrosion even at moderate temperatures with significant dissolution of carbide and grain boundaries. Alterative refractory metals and ceramics will then be discussed and some issues that arise in system often described as immune to lithium corrosion.
I will then move to look at the possibility of looking at novel ceramic materials for tritium breeding, focusing on materials with higher lithium atomic fractions than conventionally proposed. This will include effect of radiation damage on the octo-lithium (Li₈XO₆) compounds (where X=Sn,Zr,Pb or Ce) and solid state interactions between Li₂O and proposed structural materials showing that there are many common issues in materials degradation between solid and liquid breeder materials. 

Bio: My first degree was in Materials Science at St Anne’s College, Oxford. This was followed by a DPhil at Corpus Christi, Oxford developing novel methods for measuring micromechanical properties in copper and nickel alloys. 
In 2009 I was awarded the Culham Centre for Fusion Energy Junior Research fellowship at St Edmund Hall. This fellowship allowed me to apply micromechanical testing methods developed in my doctoral studies to materials for fusion power – in particular irradiated tungsten alloys where I showed that implantation of helium can significantly alter mechanical behaviour of tungsten. In 2013 I was awarded a 5-year Royal Academy of Engineering Research Fellowship titled “Micro-engineering advanced alloys for extreme nuclear power environments”. This was focused on developing methods of measuring mechanical behaviour of materials at the nanoscale at temperatures up to 1300 K. In 2015 I was awarded the Institute of Materials Minerals and Mining Grunfeld Memorial Award & Medal, for a professional contribution that has had significant influence on engineering applications in the metallurgical industries and in 2022 I was awarded the title of Professor of Materials Science and Engineering.