Globally, many nuclear power reactors are coming to the end of their 40-year operating life. Due to rising energy demands, our energy needs won’t be covered by the planned new builds, hence many efforts are being made to extend currently running nuclear power plants up to 60 years.
My DPhil is partnered with Vattenfall, who own the Ringhals reactors in Sweden. My research is focused specifically on the microstructural changes in welds from the pressurisers that have been thermally aged at 345°C for up to 295,000h. Pressurisers are unique in the fact that they are the only part of a Pressurized Water Reactor (PWR) in the primary loop that aren’t irradiated. Focusing on thermal aging and comparing this with irradiated samples will bring new insight into the reasons for degradation of nuclear reactor materials over time.
Thanks to previous research, we know that alloy-rich clusters form throughout the pressuriser steel but specifically affect the Submerged Arc Welds (SAW). The welds display extensive influence of thermal embrittlement and hardening. I am using many techniques to help my investigation such as, Nano-indentation, Focused Ion Beam (FIB) and Atom Probe Tomography (APT). These methods will me identify where the clusters are forming and how this is affecting the mechanical properties of the pressuriser steel such as hardening.
