Daniel Long
PhD Student - Imperial College London
Project Title: Modelling Delayed Hydride Cracking and Crack Growth in Zirconium Cladding
Daniel Long completed an MEngSc in Mechanical Engineering at the National University of Ireland, Galway. His research project there led him to pursue a PhD with the Computational Micromechanics group, supervised by Prof. Fionn Dunne at Imperial College London. Daniel’s PhD project is sponsored by Rolls-Royce and aims to develop computational models to enable understanding of delayed hydride cracking (DHC) in zirconium alloys.
DHC is a phenomenon which can occur in metallic alloys subjected to thermal cycling. At elevated temperatures, hydrogen diffuses preferentially to crack tips and precipitates at high concentrations, forming hydride phases. These hydride precipitates give rise to stress concentration at crack tips and can influence crack growth-rates significantly. DHC is of particular interest in zirconium alloys, which are used as cladding material in nuclear reactors. The project aims to develop novel crystal plasticity models, coupled with hydrogen diffusion models (accounting for hydride formation and dissolution), building upon a computational modelling framework developed by Dr David Wilson, which enabled mechanistic understanding of fatigue crack growth in zirconium alloys. The influence of hydrogen content on crack growth rate and direction in zirconium alloys under cyclic loading will be investigated, and hence, a more mechanistic understanding of cyclic crack growth characteristics in real materials will be gained. More generally, this work aims to provide an understanding of the influence of microstructural characteristics on crack growth-rate, acceleration, deceleration, and tortuosity.
“Pursuing a PhD linked with the nuclear energy sector has been an excellent decision for me. There is a vast network of students, academics, and industrial workers with shared goals and ambition, creating a very useful collaborative environment.”