Influence of hydrogen on irradiation damage features in Zr-based alloys

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Project Description: (maximum of 4,000 characters)EPSRC staff reading the project details will be trying to determine which of our research areas the project fits into (it could be more than one). To help them do this, project details provided should be as specific as possible and clearly describe:1) the research questions the project is trying to address/the objectives of the project; 2) the approach that will be taken to answer these questions (what the student will actually be doing); 3) the novel engineering and/or physical sciences content of the research (the science that places it within EPSRC's remit).If you think you know which EPSRC research areas are relevant to the project, it would be helpful to include this. The project description should be written so as to be understandable by an educated lay-person and any acronyms should be defined. Zirconium based materials are used for fuel rod cladding tubes and fuel assembly structuralcomponents in civil nuclear reactors. Hydrogen content has been shown to play an important role inenhancing irradiation induced growth in some Zr alloys, however little is known about the mechanisms that govern this effect. This project aims to use a range of techniques to investigate correlations between hydrogen and changes in irradiation damage evolution, thereby providing new insight into the mechanisms that affect growth. This key question this project will focus on is:What are the mechanistic reasons for the effect of hydrogen on irradiation damage and irradiationinduced growth?A carefully selected set of samples of Zr based alloys irradiated in the Vogtle reactor has been provided by Westinghouse. The unique matrix includes samples with and without hydrogen precharging,irradiated to four different fast neutron fluence levels. XRD line profile analysis and TEM will be used to quantitatively compare how loop structures develop as function of fluence. TEM and APT will be used to understand any differences in chemical segregation and to investigate the association of loops with hydrogen localization. Given the inherent difficulties associated with mapping hydrogen, additional surrogate samples will be produced by proton irradiation of deuterium charged material, facilitating identification of H/D localization by APT. The overall aim of the project is to increase our understanding of how hydrogen affects irradiation damage, thereby enabling development of improved modelling tools and the confidence to predict how to achieve improved utilization of expensive fuel and reduce waste.EPSRC themes: Advanced Materials, Energy & Decarbonisation