BIAPWS Award 2010
Angela Bradbury at Serco's Materials and Component Research Laboratory (MCRL) at Risley
Through co-sponsorship by BIAPWS and Serco Technical Consulting Services (TCS), I undertook a placement within the Materials and Component Research Laboratory (MCRL) at Risley in 2010. As I am studying Materials Science (as part of the Natural Sciences Tripos at Cambridge University), I enjoyed the opportunity to apply my theoretical knowledge to a commercial application. In addition, my time at Serco enabled me to develop invaluable skills including writing reports, statistical analysis, presenting data and working in a team.
The performance of austenitic stainless steels exposed to pressurized water reactor (PWR) primary coolant conditions has generally been good. Nevertheless, there have been some occurrences of stress corrosion cracking (SCC), particularly in coastal nuclear plants and marine propulsion systems where the presence of saline deposits is an ever constant threat. This has prompted concerns for safety, system availability and whole-life costs - concerns not only affecting existing operational systems, but also important for optimising design and fabrication in future developments.
There is extensive evidence in the open literature that the surface condition of engineering alloys, including the degree of surface roughness, the level of residual stress and surface hardness or phase transformation due to local cold work, can influence their susceptibility to environmentally assisted cracking (EAC). Serco, in collaboration with the National Physical Laboratory (NPL), have undertaken a unique approach to this topic, combining their expertise and facilities for near-surface characterisation of mechanical and material properties and for stress corrosion evaluation. My task was to write a report bringing together the relevant work during last few years. This comprised a summary of the established knowledge, a literature review of externally published work and findings of recent internal projects (both completed and ongoing).
There was a particular focus on one project at Serco, which investigates the low-temperature SCC of unsensitised 304L specimens after milling, grinding and dressing. As I was involved in producing the final report which was due to be finished at the end of September, part of my work was to analyse the results of the SCC testing. I was asked to present my analysis at a meeting with the scientists we have been collaborating with at NPL, including a discussion relating the results to the work done at NPL. It was gratifying to be so involved in developing the understanding of a topic which affects real-life systems, and I also gained experience of presenting to experts and fielding their questions about my work.
To widen my understanding of current practices actually employed in industry, I undertook visits to Rolls-Royce and Rugeley Power Station, where I learnt about machining, inspection and repair processes from site engineers. In order to provide recommendations for industry, I also reviewed potential surface modification techniques and non-destructive evaluation of surface characteristics.
The project has allowed me to meet people working in a wide range of roles including technical consultants, engineers, and expert scientists, and has helped me understand how I might fit into a company such as Serco. I have thoroughly enjoyed the responsibility I have been given, whilst knowing that I could always ask for help when I needed it. I would like to thank BIAPWS and Serco for my sponsorship, and in particular Kevin Mottershead, my line manager and an excellent mentor.