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Sustainable Fusion Steels: Whole Lifecycle Design of Tokamak Vacuum Vessel Steels – Materials Strand Project

Supervisors: Professor N. Lavery, Professor C. Pleydell-Pearce & Dr Stephen Jones (Swansea University).

Background:

The successful commercialisation of fusion energy is essential for achieving global net-zero goals and UK energy security. A major challenge is developing specialised materials that meet rigorous safety, operational, and sustainability criteria, as well as being manufacturable at scale. The core objective of this project is to achieve complete lifecycle sustainability of tokamak reactor vacuum vessel steels. This will be achieved by utilising recycled steel feedstock at the start-of-life whilst minimising radioactive waste at the end-of-life.

Technical aspects:

Fusion structural materials must meet low-activation requirements, limiting elements such as nickel and molybdenum that become long-lived under neutron exposure. These elements, however, are common residuals in recycled scrap steel, which has become the primary feedstock for the modern UK steel industry due to the widespread adoption of Electric Arc Furnace (EAF) technology. The vast quantities of steel required for a fleet of fusion reactors (hundreds of thousands of tonnes) make production via EAF routes an industrial imperative, not merely an environmental consideration.

This PhD project tackles this core conflict: How can we utilise high-volume recycled steel feedstock while adhering to stringent nuclear safety standards?

We resolve this by focusing strategically on the vacuum vessel. The vacuum vessel is a critical structural component that provides a sealed, ultra-high-vacuum environment and houses the internal components of the reactor. It experiences significantly lower neutron exposure compared to the inner blanket structures. This distinction creates a permissible threshold for residual element concentrations, allowing us to specify and control scrap streams. This research, which challenges the traditional orthodoxy of requiring virgin purity for nuclear materials, represents an engineering approach that integrates fusion deployment with existing industrial systems and circular economy principles.

Research Methodology: Computational Design & Rapid Alloy Prototyping:

The project uses an Integrated Computational Materials Engineering (ICME) approach to accelerate alloy discovery and minimise resource consumption.

  1. Computational screening: CALPHAD (Calculation of Phase Diagrams) and machine-learning tools will be used to identify reduced-activation alloy compositions before physical production.
  2. Rapid Alloy Prototyping (RAP): Selected alloys will be produced using lab-scale alloy production methods, with both synthetic and industrial scrap inputs, supported by industrial guidance on realistic scrap-stream tolerances.
  3. Manufacturing assessment: Candidate materials will be evaluated for large-scale processing routes and joining methods relevant to fusion-reactor assembly.

Training and Support:

The IGNITE project (Indigenous Green-steel for Net-zero Innovation, Technology & Enterprise) is led by Prof. Pleydell-Pearce at Swansea University and is a major national programme bringing together academia and industry. IGNITE aims to produce research that leads to a fundamental transformation of the UK steel industry through development of novel green steels and lifecycle circularity. This provides the ideal context for this project, with access to the industrial ecosystem, such as scrap processors and steel manufacturers, necessary for translation of the fundamental research into real-world impact.

The work will be conducted within MACH1 (Materials Advanced Characterisation) at Swansea University, led by Prof. Nicholas Lavery, which has an established collaboration with UKAEA on fusion steel development [1-3], particularly the NEURONE project where Swansea is leading the alloy development of next generation RAFM steels for fusion. MACH1 led the Prosperity Partnership in Rapid Product Development, a large programme of research that developed RAP for the UK steel industry. A previous pilot project, funded through UKAEA’s Fusion Industry Partners (FIP) scheme, and co-led by Dr Stephen Jones focused on the development of novel steels for fusion reactor vacuum vessels. These projects provide the technical foundation that this PhD will extend by introducing sustainability and circularity considerations.

Throughout the duration of the PhD project, the student will work alongside other IGNITE PhD students, working on similar projects involved in the transformation of the UK steel sector. In addition to their academic supervisors, these students will be supported by a dedicated IGNITE PDRA (Post Doctoral Research Associate), who will provide day-to-day guidance and technical support.

The student will acquire a comprehensive, multidisciplinary skillset essential for careers in advanced energy and manufacturing sectors, gaining expertise in computational design, alloy development, advanced materials characterisation, scientific communication, analytical skills, teamwork, project management, and collaboration across academic and industrial partners.

This experience prepares the student to be a future leader, capable of integrating materials science with large-scale industrial reality to deliver sustainable solutions for fusion energy. They will deliver a verified, sustainable material route for fusion vacuum-vessel steels, reducing reliance on virgin raw materials, lowering long-term radioactive waste, and supporting a domestic, circular, and economically viable supply chain for the UK fusion sector.

[1] D. Bowden et al. “Engineering the Next Generation of Industrially Scalable Fusion-Grade Steels”, Journal Nuclear Engineering (forthcoming at later stages of review).

[2] D. Bowden et al., “Development of Industrially Scalable High-Temperature Steels for Fusion Applications”, TMS Annual Meeting & Exhibition, Las Vegas, USA, 2025.

[3] J. Haley et al., “Complete dissolution of MX-phase nanoprecipitates in fusion steels during irradiation by heavy-ions” Journal of Nuclear Materials 596, 2024. J Nuc. Mat 10.1016/j.jnucmat.2024.155115

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.

This project will be based at Swansea University but will attend events (workshops and events) for both the Fusion CDT, as well as the IGNITE project.

This project will be mainly based in Swansea, but will bring together complementary expertise across academia, industry, and the public sector to address this complex challenge.

Internal Collaboration within Swansea University:

  • MACH1: Rapid alloy prototyping, thermodynamic modelling, fusion materials expertise.
  • ISM: Advanced mechanical testing, microstructural characterisation.
  • SAMI: Industrial scale-up, scrap characterisation, recycling process optimisation.

Industry-Academia Collaboration:

Sheffield Forgemasters: steel manufacturing expertise, industrial validation of lab-scale results, access to production-scale facilities for demonstration and industrial scale process modelling.

Tokamak Energy: specific design requirements, commercial perspective, routes to implementation in reactors.

Public Sector Engagement: UKAEA: strategic oversight, alignment with national fusion priorities, neutron activation calculations, integration with STEP programme requirements, regulatory guidance on waste classification criteria.

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

This project is being offered by Swansea University as part of the Fusion CDT Community Studentship scheme.

For further information and details of how to apply please contact: Professor Nick Lavery (N.P.Lavery@swansea.ac.uk) or Professor Cameron Pleydell-Pearce (C.Pleydell-Pearce@Swansea.ac.uk).