Advanced chemistry and corrosion studies under hot water conditions relevant to LWR coolant

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This student will be investigating hot water corrosion of nuclear reactor steels using advanced materials characterisation, under the supervision of Dr Tomas Martin, Dr Oliver Payton and Dr Rob Burrows of NNL. The next generation of nuclear reactors in the UK, beginning with Hinckley Point C, will eschew the UK-specific gas-cooled design for the water-cooled type of reactor more commonly found in other countries with nuclear power. These light water reactors (LWR) will have significantly different components and operational design, and as such the mechanisms of corrosion, stress and fatigue in these components will be dramatically different from those currently studied in UK industry and academia. Similar pressurised water cooling systems will be used for fusion reactors such as ITER and DEMO, and will have many of the same corrosion issues.This PhD project will investigate the effects of noble-metal addition to the coolant of Boiling Water Reactors (BWRs) such as those proposed at Wylfa and Oldbury in the UK. BWRs have had a historical issue with stress corrosion cracking (SCC), where corrosion from the water coolant results in cracking of components under mechanical stress. In the USA, this problem is mitigated by changing the coolant water chemistry, injecting hydrogen, zinc and platinum to the water to reduce the effect of radiolysis and limit free radical species. Whilst the addition of these species has been confirmed to help prevent the growth of stress corrosion cracks in operational reactors, there has been little investigation of this changed water chemistry on new reactors during commissioning and testing, and on the The project will develop an autoclave testing facility in partnership with NNL and expose a series of steel and nickel alloys to LWR water conditions and a variety of water chemistries to better understand the mechanism behind corrosion and its inhibition by noble metal injection. These specimens will be characterised with a wide range of state-of-the-art surface and materials analysis techniques, including electron microscopy, electron backscatter diffraction, X-ray diffraction and focused ion beam milling. By creating small cantilevers of stressed material, the effect of localised SCC will be explored using high resolution chemistry mapping tools such as transmission electron microscopy and atom probe tomography. In addition to the main research work using autoclave corrosion experiments, the project will probe the mechanism of corrosion at the nanoscale using electronic mapping of the workfunction using the NanoESCA combined with live imaging of corrosion using high-speed atomic force microscopy in a liquid cell.