Liquid lithium breeder blankets combined with vanadium alloys, particularly V-4Cr-4Ti (V44), are a highly promising concept capable of achieving high tritium breeding ratios with much lower Li-6 enrichment than other blanket designs. V44 is selected for its excellent compatibility with liquid lithium, alongside high thermal conductivity, low neutron activation, good irradiation tolerance like swelling resistance, and good thermal creep strength. Specifically for fusion applications, baseline V44 offers a much higher high operating temperature window (~400 to >700 °C), as compared to reduced activation ferritic-martensitic steels. The lower temperature limit of ~400 °C is imposed due to the complexity of managing low temperature hardening-embrittlement (LTHE) phenomenon of structural components under irradiation – which causes toughness loss and loss of ductility below 400 °C. The upper temperature limit of 700 °C is currently imposed from structural integrity viewpoint because of thermal softening and creep strength loss in V44.
A key challenge is that complex large-scale engineering structures like the first-wall/blanket for fusion will inevitably require joining. Electron beam (e-beam) welding is currently the primary technique for V44 in fusion applications. However, little is known about in-service degradation and failure modes of V44 e-beam welds under fusion-relevant conditions which can be used to postulate structural design criteria. Welds—often structural weak points—must withstand fusion’s extreme environment: elevated operating temperatures (upto 700-750 °C), high neutron doses (up to 150-200 displacements per atom, dpa), and the presence of helium/hydrogen from transmutation. The relationship between welding process, post-weld heat treatments (PWHTs), and radiation tolerance remains poorly understood, limiting the ability to inform design and safety criteria.
Project Scope: This project will address the engineering grand challenge of understanding degradation and failure modes in V44 e-beam welds under fusion-relevant conditions, with a focus on blanket design. Key questions include:
- Understanding the effect of irradiation dose and temperature on hardening regimes of e-beam welds and identify the safe operating temperature window for blanket operations.
- Quantifying the role of helium on the safe operating temperature window for welds and postulate safety criteria based on experimental data
- Elucidate the effect of e-beam environmental conditions on irradiation performance.
Supervision and International Collaborations: You will be based at the University of Birmingham and co-supervised by industry leaders from EPRI (https://www.epri.com/). This project will involve multi-national collaborators, and so you will have a unique opportunity to work with renowned experts from world-recognized institutes such as CNRS IJCLab (France), Karlsruhe Institute of Technology (Germany) and Tokamak Energy (UK). You will work as part of the Fusion Engineering CDT cohort in a diverse, inclusive, multi-cultural and collaborative environment that nurtures excellence and innovation to tackle some of the world’s biggest challenges such as fusion energy.
Who we are looking for: A first or upper-second-class degree in an appropriate discipline such as nuclear engineering, chemical engineering, physics, chemistry, mechanical engineering, materials engineering to name a few. A driven individual with an inquisitive mind.
For Informal inquiries, contact: Professor Arun Bhattacharya – a.bhattacharya.1@bham.ac.uk or Dr. Andrew Sowder (asowder@epri.com)Please include your CV and transcripts.
This EngD project is set within the Fusion Engineering CDT at the University of Birmhingham. Students will recieve a 3-month training programme in fusion engineering at the start of the course, delivered across the CDT partner universities. For further information about the CDT, please visit the website or send an email to hello@fusion-engineering-cdt.ac.uk.
Apply for this project now at the University of Brimingham at https://www.birmingham.ac.uk/study/postgraduate/apply.
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