Radiation effects in reduced activation ferritic-martensitic (RAFM) steel welds for fusion first-wall/blanket applications

About the Project

A 3.5-year UK PhD studentship is available at the University of Birmingham with a tax-free stipend at UKRI rate. The project is collaborated with Oxford Sigma, Karlsruhe Institute of Technology (KIT) in Germany, French National Centre for Scientific Research (CNRS)’s JANNUS irradiation facility and CEA-Saclay.

Background:

RAFM steels are promising candidates for most fusion reactor first-wall/blanket concepts. A key challenge is the very narrow safe operating temperature window envisaged for RAFM steels, between 350 – 550 °C, in an irradiation environment of fusion reactors [1,2]. The lower temperature limit, which is a major design-limiting challenge for Demonstration Power Plant (DEMO), is imposed due to the well-known low-temperature hardening/embrittlement (LTHE) phenomenon under irradiation, where the steel hardens with severe loss of ductility & toughness [1-3]. The upper temperature limit is imposed due to cyclic softening, poor creep strength and creep-fatigue coupling in this class of materials [1,4]. In addition to base material, a key requirement for fusion in-vessel components is understanding radiation tolerance of welds because complex and large fusion in-vessel components will inevitably need to be joined together. Presently, very little is known regarding irradiation effects in welds of RAFM steels [1]. This seriously limits our understanding of safe operating limits of these welds in fusion’s extreme environment with very high neutron doses (80 to 150 displacements per atom), elevated temperatures and with simultaneous presence of gaseous transmutation products like helium (He) and hydrogen (H) – which can synergistically modify the microstructure development in materials [5]. This PhD will reveal the key irradiation-induced microstructure phenomenon in RAFM welds using in-situ & ex-situ energetic ion irradiations as a surrogate for neutron irradiations and reveal the microstructure origins of RAFM weld degradation expected in fusion-relevant conditions.

The Project:

Using in-situ & ex-situ ion irradiations, this PhD project will evaluate the effect of irradiation and transmutant gases on microstructure evolution in e-beam-, laser- and TIG-welded RAFM steels – the knowledge of which is currently limited in the fusion community. Some key questions to study include, but not limited to:

(i) Understanding the effect of irradiation dose & temperature on microstructure evolution in RAFM welds & heat-affected zones.

(ii) Understanding helium’s role on vacancy-type and interstitial-type extended defects in welds.

(iii) Triple synergy between ballistic damage and He/H on weld microstructural evolution.

Supervision and International Collaborations: You will be based at the University of Birmingham and will be co-supervised by Oxford Sigma (https://oxfordsigma.com/). You will have a unique opportunity to engage with fusion leaders from KIT/Germany, and JANNuS facility at CNRS-Orsay & CEA-Saclay in France. As a member of the Fission & Fusion Energy Sciences group you will work in a friendly, diverse, inclusive and collaborative environment that nurtures excellence and innovation in fission/fusion energy. Besides targeting academic success, this PhD will provide you the necessary mentorship for 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, physics, chemistry, nuclear engineering, fusion/nuclear energy, chemical engineering, or mechanical engineering to name a few. No prior experience is mandatory. Knowledge of nuclear materials would be advantageous. A driven individual with an inquisitive mind.

How to apply:

Informal inquiries should be sent to Professor Arun Bhattacharya – a.bhattacharya.1@bham.ac.uk, Dr. Alasdair Morrison (alasdair.morrison@oxfordsigma.com). Please include your CV and transcripts. Apply online on this link: https://sits.bham.ac.uk/lpages/EPS024.htm

Funding notes:

Funding available for UK students only.