Ultra-High-Performance Concrete Containments for Safer Small Modular Reactors

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Offering more affordable nuclear energy, small modular reactors (SMRs) are critical to Canada's low-carbon energy future. However, given the lack of experience with SMRs, their safeguards and security pose a major challenge, as emphasized by the Canadian Nuclear Safety Commission. This project addresses SMR safeguards and security pertaining to concrete containment structures. Traditionally, concrete containment structures are either pre-stressed concrete or reinforced-concrete with steel liners. However, given Canada's hostile weather conditions, the safety of conventional concrete containment structures can be jeopardized by an increased risk of concrete degradation due to freeze-and-thawing cycles or corrosion of reinforcing bars and prestressing tendons. These risks can be further exacerbated by the SMR's elevated temperatures and high internal pressure, particularly during accidents. This project proposes a new type of concrete containment structures based on ultra-high performance concrete (UHPC). UHPC exhibits a strength exceeding four times that of conventional concrete while providing an intrinsically dense microstructure, remarkable toughness, and almost impermeability to deteriorating agents. These features are advantageous for improving the robustness, radiation shielding, and leak-tightness of concrete containment structures. A new tool for optimizing UHPC mixture design will be developed while valorizing domestic materials (steel slag and magnetite sand) to produce heavy-weight, high-radiation shielding UHPC featuring high energy absorption capacity needed to resist high internal pressure, particularly during accidents. The expected pervasive impacts of this research include supporting regulatory decision making on novel concrete containment structures (with higher safety functions) as an alternative to traditional options; propelling the safety of SMR facility workers, the environment, and the public; improving the Defense-in-Depth of SMR nuclear facilities, and fostering Canada's far-front global leadership in the nuclear energy sector.