Understanding in-service degradation of conventional & reduced activation tungsten carbide for [...]

A 3.5-year UK PhD studentship is available at the University of Birmingham with a tax-free stipend. The project is co-funded by Tokamak Energy as part of the University’s Prosperity Partnership and will be collaborated with world-leading institutes in Germany, France and the US.

Background: Fusion energy holds promise to provide safe, carbon-free, reliable and near-limitless energy. Tokamak Energy, a UK-based private fusion company, and the UK’s Spherical Tokamak for Energy Production (STEP) programme aims to demonstrate commercial fusion by combining spherical tokamak (ST) designs with high-temperature superconducting (HTS) magnet technology. However, the smaller ST reactor size brings the hot fusion plasma closer to a life limiting component called a “centre-column”, that contains the HTS magnets. These magnets are susceptible to failure by radiation damage/heat, and the in-vessel fusion conditions will be severe – simultaneous presence of neutron bombardment, a wide temperature range (cryogenic to >1000 °C), intense plasma particle exposure in plasma-facing regions (>1019 particles.m-2.s-1 of deuterium, tritium, impurities etc.) and high-heat flux (HHF), few tens of MW/m2 to several GW/m2 during plasma disruptions. Minimal radiation doses, on the order of milli-dpa, have been shown to degrade REBCO performance. Moreover, the magnets must be maintained below their critical temperature to avoid quenching, a sudden transition to the normal conducting state. Therefore, high-performance, spatially efficient shielding materials are needed to sufficiently attenuate neutrons/gammas and simultaneously prevent any exposure to heat-flux or plasma-particles.

Guided by neutronics, most promising shielding concepts involve novel materials: reduced-activation binder tungsten carbide (rab-WC) and TE’s proprietary di-tungsten pentaboride (W2B5), protected in the plasma facing regions by a metallic tungsten armour. Little is known regarding in-service degradation of these materials over their wide envisaged temperature range from cryogenic to >750 °C, which is a major design challenge because shielding failure would mean centre-column failure.

The Project: This PhD will study the effect of irradiation-induced, and high heat-flux induced degradation of WC shielding materials. The study will focus on revealing the following key questions:

• Understanding the effect of irradiation dose and temperature on radiation-induced amorphization (RIA).
• Quantifying the anisotropic swelling and swelling-induced microcracking phenomenon in conventional WC and rab-WC.
• Understanding the safe operating lower temperature limit of rab-WC in an irradiation environment.

Supervision and International Collaborations: You will be based at the University of Birmingham and will be co-supervised by industry leaders from Tokamak Energy. 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 Forschungszentrum Jülich in Germany, CNRS/ University of Paris-Saclay in France, Oak Ridge National Lab/University of Tennessee in the US, UK Atomic Energy Authority and industrial materials manufacturers. You will work as part of the University of Birmingham and Tokamak Energy’s Prosperity Partnership team in a diverse, inclusive, multi-cultural and collaborative environment that nurtures excellence and innovation to tackle some of the world’s biggest challenges. Besides targeting academic success, this PhD will provide you the necessary mentorship so that you can have a prosperous post-PhD career.

Who we are looking for: A first or upper-second-class degree in an appropriate discipline such as materials science and engineering, nuclear engineering, chemical engineering, physics, or mechanical engineering. No prior experience is mandatory. Some knowledge of fusion basics and/or microstructural characterisation would be advantageous. A driven individual with an inquisitive mind.

Contact: Informal inquiries should be sent to Professor Arun Bhattacharya and Dr. Samara Levine. Please include your CV and transcripts.