Impact of helium from nuclear transmutation and from plasma on tritium trapping in fusion structural and plasma-facing component

Background: Future fusion energy concepts such as ITER, DEMO or STEP rely upon deuterium-tritium (D-T) fusion reaction, which holds the promise of generating limitless clean energy. But tritium availability on earth is scarce (less than 30 kg), making it a very expensive fuel, and tritium is a radiological hazard. Therefore, understanding in-service pathways of tritium loss and proper tritium accountancy is crucial to the success of future fusion energy systems. A key challenge is tritium can be trapped strongly by radiation-induced & plasma-induced microstructural defects under fusion-relevant extreme environments. For structural material candidates like RAFM or ODS steels, these defects are vacancy-type/interstitial-type extended defects, and high concentration of gas-stabilized helium (He)-vacancy clusters and He-filled cavities. Helium in materials originate from (n, α) transmutation reaction by 14 MeV neutrons from D-T fusion. Further, helium will also be introduced directly from the plasma in W-based plasma-facing components (PFCs). Vacancy clusters and He-filled cavities are likely to be the major tritium traps in fusion in-vessel components. Due to this, serious concerns remain on two overarching issues: firstly, tritium trapped in materials is deleterious to fuel self-sufficiency requirement of a fusion power plant and the second concern is safety in case of a loss of vacuum accident (LOVA) where tritium trapped in components may be released to the environment. Therefore, it is essential to ensure minimal tritium retention occurs, which necessitates a thorough understanding of hydrogen isotope interaction with microstructural defects in fusion materials.

The Project: This PhD will study the effect of irradiation-induced & plasma-induced microstructure degradation on tritium trapping in fusion first-wall/blanket materials and PFCs. The study will focus on the two following sub-areas : (i) Understanding the role of He-bubbles on tritium trapping under synergistic irradiation and plasma exposure in PFCs (pure W and additively manufactured W alloys). (ii) Understanding the effect of He-filled cavities and He/dpa ratio on tritium trapping in RAFM and ODS steels.

Supervision and International Collaborations: You will be based at the University of Birmingham and will be co-supervised by the UKAEA’s Tritium Fuel Cycle division (https://ccfe.ukaea.uk/divisions/h3at). 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 Oak Ridge National Lab/University of Tennessee in the US, CEA-Cadarache & University of Paris-Saclay in France, and Forschungszentrum Jülich in Germany. You will work in a diverse, inclusive, friendly and collaborative environment that nurtures excellence and innovation to tackle some of the world’s biggest challenges, such as fusion energy. You will be given proper mentorship for a successful post-PhD career.

Who we are looking for: A first or upper-second-class degree in an appropriate discipline: materials science and engineering, nuclear/chemical/mechanical/aerospace engineering, physics, plasma-physics, condensed-matter physics. No prior experience is mandatory. Some exposure to microstructural characterisation, hydrogen materials interaction and/or, fission/fusion basics would be advantageous. A self-motivated, inquisitive, genuine and driven individual.

Contact: Please contact Professor Arunodaya Bhattacharya – a.bhattacharya.1@bham.ac.uk and/or Dr. Rosemary Brown – rosemary.brown@ukaea.uk to discuss your motivation. Include the following: CV and transcripts.