Ensuring the Safety of Nuclear Waste Contaiment
Meet Thalia Standish
Dr. David Shoesmith and Dr. Jamie Noël
Corrosion and degradation of nuclear fuel waste containers
NSERC Canadian Graduate Scholarship -Doctoral
Mitacs Accelerate Internship
T. E. Standish, M. Yari, D. W. Shoesmith, and J. J. Noël. “Crevice Corrosion of Grade-2 Titanium in Saline Solutions at Different Temperatures and Oxygen Concentrations,” J. Electrochem. Soc., vol. 164, pp. C788-C795, 2017.
T. E. Standish, D. Zagidulin, S. Ramamurthy, J. J. Noël, P. G. Keech, and D. W. Shoesmith, “Galvanic Corrosion of Copper-Coated Carbon Steel for Used Nuclear Fuel Containers,” Corros. Eng. Sci. Techn., vol. 52, pp. 65-69, 2017
T. E. Standish, J. Chen, R. Jacklin, P. Jakupi, S. Ramamurthy, P. Keech, and D. W. Shoesmith. “Corrosion of Copper-Coated Steel High Level Nuclear Waste Containers Under Permanent Disposal Conditions,” Electrochim. Acta, vol. 211, pp. 331–342, 2016.
Standish is in her fourth year of her PhD. During her degree she did an eight-month internship at the Nuclear Waste Management Organization, where she used high-power computing and software to conduct her research. After her degree, Standish is hoping to pursue industry working in imaging materials and examining material degradation.
Containing and storing spent nuclear fuel on the time scale of 100,000s of years is a national challenge currently facing Canada. Though nuclear power currently meets more than 50% of Ontario’s power production, finding a safe and permanent storage system for this radioactive fuel is still an elusive goal yet to be meet. Currently nuclear fuel is store in temporary storage facility, but the goal is to find a permanent storage solution. Dr. David Shoesmith and Dr. Jamie Noel from Western Science’s Chemistry department co-supervise Thalia Standish, a PhD candidate, working to investigate the longevity of the propose containment systems.
The current proposed permeant solution is to bury steel containers coated with copper deep into the ground; however, any container must be able to resist the corrosion of the groundwater percolating down to towards the buried containers. Standish’s research evaluates the corrosion rates of these material under conditions expected underground and how these systems preform over time. Standish looks primarily at what happens to these systems when a defect is present in the copper coating and the steel can interact with water and dissolved oxygen. When this occurs the steel has the potential to undergo accelerated corrosion because it is now reacting with both the copper and groundwater.
To address this, Standish uses electrochemistry and image analysis to see how the corrosion happens and progresses while deterring the influence of different environmental parameters. By taking plates of steel that have been coated in copper, Standish makes 2 mm wide cylinders that have a small hole drilled through the copper coating to the copper-steel interface that’s 0.5 mm wide. The samples are then placed into solution and undergo different electrochemical conditions to analyze the rate of corrosion and the performance of these materials.
To examine the changes in the surfaces, Standish uses state-of-art imaging instruments such as micro computed tomography (micro-CT), which is a non-destructive 3D imaging technique. This technique allows Standish to examine the material in-situ without removing the samples from solution and changing the environment. She is therefore able to image over different time points and see how the corrosion is progressing over time allowing for a realistic measurement of the material under the conditions excepted deep underground.
From this work, the research has produced a database that tells the user the amount of steel lost and rate of that corrosion under different environmental conditions. This provides an essential safety tool for determining how these materials should perform over their expected lifetimes and addressing the what-if questions regarding worst outcome scenarios.