Steel for STEP; Making materials to contain a star
Using the Royce 25 kg VIM, our technical specialists have taken the first steps to scaling up the production of novel steels that could form vital components of fusion energy generators.
NEURONE aims to provide an industrially scalable fusion-grade advanced steel capable of operating at 650°C in a fusion breeder-blanket environment.
Fusion power plants such as the Spherical Tokamak for Energy Production (STEP) under development by the UK Atomic Energy Authority (UKAEA) require coolant operating at temperatures up to 650°C.
The steels being developed within the NEURONE programme, rely on nano-scale particles to strengthen the material and improve resilience to radiation damage. They offer an increase to the maximum operating temperature of fusion power plant components.
Steels are produced using carefully selected alloying elements, reducing residual radioactivity and forming sufficient strengthening phases to enable acceptable performance in a fusion energy environment. This is coupled with thermomechanical treatments developed to exploit these strengthening mechanisms and evolve the required microstructures.
Initially developing these materials at lab-scale, ultimately NEURONE’s aims to translate their processes to industrial-scale for the construction of future fusion power plants.
This body of research, led by Prof. Eric Palmiere and Prof. Mark Rainforth, applies alloy design, melting, casting, and thermomechanical processing to produce new steels with promising combinations of microstructural and mechanical properties to support the development of functional fusion power generators.
Dr. Yunus Azakli (Technology Platform Lead: Materials Development and Prototyping) cast a number of 25 kg Advanced Reduced Activation Ferritic Martensitic (ARAFM) steel ingots using the Consarc 25 kg VIM, demonstrating the first step towards scale-up from its initial development (at 10 kg). This ingots were subject to a journey through a number of the Advanced Metals Processing capabilities, exploring the material’s performance and properties; including Hot Rolling (FENN model 081 laboratory reversing mill) and Thermomechanical Compression (TMC) (ServoTest TMTS 61436).
This body of work successfully scaled up the manufacturing of ARAFM ingots with very tight compositional specifications from 6 kg developmental work to 20 kg. Additionally, this specific composition showed superior properties compared to EUROFER97 under consideration for the manufacture of future fusion energy generators. The work provided valuable information on the processing behaviour of these steels, demonstrating feasibility for industrial level process optimisation and scale-up.