Grant: Discovery Launch Supplement

In the fight against climate change, many governments have given renewed focus to nuclear energy due to its low greenhouse gas emissions and consistent baseload power relative to weather-based, intermittent renewables. Moreover, next-generation nuclear reactor designs such as molten salt reactors (MSRs) offer advantages such as high output temperatures, allowing the heat to be used in industrial processes currently reliant on fossil fuels or thermal energy storage, complementing intermittent renewable energy. MSR designs use either chloride or fluoride-based molten salt as a coolant, with the fissile fuel typically dissolved into the salt. MSRs also operate at lower vapour pressures and higher temperatures compared to water-cooled nuclear power plants (NPPs) and thus provide safety advantages and higher thermal efficiencies. Furthermore, MSRs offer the possibility of using both uranium and thorium-based fuel as well as reprocessed spent fuel from other NPPs, reducing the used fuel inventory for long-term storage. Despite the benefits offered by MSRs, a major barrier to the commercial deployment of MSRs stems from the corrosion that structural alloys (like stainless steel and nickel alloys) undergo in molten salts, which if weakened by corrosion, can lead to major structural failure. In partnership with the Colorado School of Mines (Mines), the Canadian Nuclear Laboratories (CNL), and the Canadian Light Source (CLS), Prof. Situm's research group is testing novel strategies to mitigate this corrosion, such as inserting a sacrificial rod of zirconium into the molten salt which will corrode in place of the structural alloys, or using special alloys designed and developed by Mines with additive manufacturing (AM) techniques that can allow one side to be resistant to corrosion while the rest of the material retains full strength. Since these strategies will be implemented within a nuclear reactor, the group is also simulating the effects of radiation on these materials by inducing helium buildup within them to see if the corrosion mitigation strategies still work as expected. Prof. Situm's state-of-the-art research laboratory allows in situ electrochemistry and Raman spectroscopy to be performed to monitor and characterize the corrosion process in real-time, with ex situ characterization being performed at CNL and the CLS. Overall, the results of this research will contribute to a broader effort to deploy MSRs to help Canada meet its greenhouse gas emission targets laid out in the Paris Climate Accord, and is of interest to both companies developing MSR designs and governmental regulatory bodies such as the Canadian Nuclear Safety Commission (CNSC). If Canada can resume the role previously played by Atomic Energy of Canada Limited (AECL) in exporting Canadian-made nuclear reactors internationally, this can help developing countries who lack the technical expertise to create a nuclear program to obtain safe, clean energy.