Consideration of Co incorporation behavior in oxide film under advanced boiling water reactor conditions

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Boiling water reactors (BWRs) operates in high-purity water at temperatures up to 288C in saturated steam and water at pressure ~70 Bar and most structural components and piping are made out of stainless steel thanks to their good strength and corrosion resistance properties. However, when stainless steel corrodes in high temperature water, non-radioactive cobalt 59, which is an impurity in structural materials, is released into the water, gets activated and become radioactive Co-60. This Co-60 in the reactor coolant water can then be incorporated within the oxide film of the structural materials in the BWR and cause workers to be irradiated during inspection and maintenance. To reduce occupational exposure of workers, water chemistry of coolant is adequately controlled and new build plants will probably apply on-line NobleChem (OLNC) with hydrogen water chemistry (HWC) in combination with zinc injection in the water to reduces the Co-60 incorporation and mitigate the corrosive behaviour of structural materials. However the mechanistic understanding of the Co incorporation in the oxide is not fully understood. Therefore the aim of this project is to develop a scientific understanding of the synergisms of different water chemistry treatments on oxide evolution so that the water chemistry of the next generation power plants can be optimized. The project will be carried out at the Materials Performance Centre, part of the Department of Materials and one the centres of the Nuclear Dalton Institute at the University of Manchester. The centre has extensive expertise in microstructural characterization, metallurgy, oxidation, and structural integrity of nuclear components and has a large number of state-of-the-art material characterization facilities and autoclaves for replicating nuclear environments. The successful candidate will acquire skills in materials performance and will become proficient in the materials and microstructural characterization, which include secondary electron microscopy (SEM), focused ion beam (FIB), transmission electron microscopy (TEM), X-ray diffraction (XRD) and other advanced characterization techniques.