The science
Fusion power plants such as the Spherical Tokamak for Energy Production (STEP) require coolant operating temperatures up to 650°C. This is to increase the efficiency of the plant, enabling additional electricity to be generated.
The steels being developed within the NEURONE programme, rely on nano-scale particles to strengthen the material and improve resilience to radiation damage. These steels are designed to offer an increase to the maximum operating temperature of fusion plant components.
These steels are produced using carefully selected alloying elements, reducing residual radioactivity, yet enabling the alloy to form sufficient strengthening phases to enable acceptable performance in a fusion environment. We couple this with thermomechanical treatments which are developed to exploit these strengthening mechanisms and evolve the microstructures we require.
We do all of this with a view to ensure that what we produce in the lab, is achievable at scale in industry. This is because ultimately, these steels will be utilised in future fusion plants, and will rely on industrial upscaling and processing.
Typical microstructure of NEURONE alloy. Shown using electron backscatter diffraction imaging, whereby crystallite orientation is visible.
Objectives and timeline
Aim
Develop and deliver an industrially scalable fusion-grade advanced steel capable of operating at 650°C in a fusion breeder-blanket environment.
Objectives
- Produce the representative advanced steel at tonnage-scale for use in the LIBRTI breeder blanket mock-up.
- Deliver the first iteration of a materials property handbook providing both baseline and irradiated material property data for a final selected steel variant.
- Produce a steel which offers both thermodynamic and irradiation stability within a fusion environment.
- Understand and manipulate defect sinks through controlled precipitate evolution, second phase interface optimisation and novel microstructure design.
- Development of thermomechanical treatments (TMTs) to deliver the required microstructures and offer scalability of process parameters to industrial scale.
- Better understand and manage the governing factors behind steel performance in a fusion plant, namely through the interaction of thermal creep, irradiation damage and ultimately (synergistic) irradiation creep effects.
- Assess and down select the optimal joining/welding approaches that minimise the in-service degradation of the alloy, towards delivery of a breeder blanket mock-up.
Timeline
NEURONE officially commenced in 2024 within the Fusion Futures funded LIBRTI programme. NEURONE will continue to run until early 2028.
Preparing a lab-scale melt of NEURONE alloy using the centrifugal caster.
Partners
NEURONE is working with over 70 collaborators across 12 organisations to deliver scalable, fusion-grade commercial steel by 2028.
The partner organisations and their roles are:
Government:
- UKAEA: Programme management, establishing technical direction and operational requirements.
- Australian Nuclear Science and Technology Organisation (ANSTO): Neutron irradiation of material using the Open Pool Australian Lightwater (OPAL) reactor.
Academia:
- Swansea University: Alloy development and screening within the MACH1 laboratory. Mechanical testing and analysis within the Institute for Structural Materials (ISM).
- University of Sheffield: Alloy development and screening.
- University of Birmingham: Alloy development and screening. Proton irradiation and synergistic effects.
- University of Manchester: Material characterisation (primarily using transmission electron microscopy (TEM)).
- University of Oxford: Material characterisation (primarily using atom probe microscopy (APT)). Hot nanoindentation of materials.
- University of Bristol: Assessing high thermal flux exposure of fusion-grade steels.
- Imperial College London: Atomistic modelling of precipitate stability and defect interaction within fusion-grade steels. Mechanical testing utilising Materials Testing 2.0 methodologies and data-rich techniques.
- University of Strathclyde Glasgow: Assessment of various manufacturing techniques towards a mock-up component.
Industry:
- Materials Processing Institute: Upscaling to kilogram and tonnage sizes. Subsequent alloy thermomechanical treatments (TMTs).
- Sheffield Forgemasters International Limited: Ingot solidification modelling and upscaling to multi-tonne scale.
NEURONE work packages and partners
Achievements
NEURONE officially commenced in 2024 and has so far made a number of major achievements, including:
- NEURONE has successfully produced the first multi-tonne UK reduced-activation ferritic martensitic steel, demonstrating the UK’s capability to scale up production for advanced variants in the future – Read the article.
- Successful production of over 50 alloy variants, advancing the search for an optimal fusion-ready steel.
- Established compositional space and process methodology using thermomechanical treatments (TMTs) – publication imminent
- Establishment of a comprehensive testing framework, including irradiation campaigns in material test reactors worldwide.
- Investigated irradiation stability of VN precipitates – Read the publication.
- Developed atomistic modelling capability to predict stability of MX precipitates in steel whilst under irradiation – publication imminent.
- Supporting 6 PDRAs, 9 student placements (to date) and 10 PhD projects within the programme.
