The reactor pressure vessel (RPV) is the primary containment vessel in light water nuclear power plants. During operation, RPVs become embrittled due to neutron irradiation at elevated temperature. Replacing the RPV is prohibitively expensive, and the operational lifetime of the power plant is limited by the safe operational lifetime of the RPV. It is therefore critical that we can accurately and reliably predict embrittlement of RPV steels to optimise the safe operational lifetime of reactors.
To do this, we must understand the fundamental degradation mechanisms that control embrittlement. Previous work has shown that significant embrittlement occurs due to the formation of solute clusters. However, the nature of these features (i.e. their composition and whether they are distinct phases) is still contentious, which has significant implications for our ability to accurately predict their formation and evolution and during service.
This project, in collaboration with Rolls-Royce Plc, will use Atom Probe Tomography (APT) alongside correlative techniques such as Transmission Electron Microscopy (TEM) and Small Angle Neutron Scattering (SANS) to investigate clustering in a range of model steels with systematic changes in their composition, after exposure to thermal treatments and neutron irradiation. The advanced characterisation will be complemented with hardness testing, with the aim of understanding better the link between cluster formation and embrittlement. This still has several key unknowns, such as the role of solute Mn, and how to accurately link the influence of precipitates to noted yield strength/hardening.
The use of state-of-the-art APT instruments, such as a LEAP 6000, will further enable investigations towards improving the accuracy of compositional measurements made by APT. The findings from this work will be critical in understanding the nature and mechanisms of formation of hardening features in RPV steels, and the data generated will support more accurate predictions of RPV properties through-life.
This project is fully funded by Rolls Royce and it is restricted to Home applicants. The studentship will cover fees at Home rate and stipend of at least £21,708 pa.
