Establishing an open, systems level technical basis in determining the SMR emergency planning zone (EPZ)

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The emergency planning zone (EPZ) of a Small Modular Reactor (SMR) can be smaller (in size) than traditional larger, reactor designs that are currently operating in Canada and globally. The EPZ of SMR technically depends on its "safety-in-design"; that is, integrated passive and inherent safety features are expected to reduce the probability of unanticipated accidents to be increasingly small or eliminated by design. The SMR's ability to mitigate consequences from design extension conditions is also expected. Compared to existing legacy designs, one expects a technical basis to substantiate the EPZ, rather than original recommendations (with sufficient safety margins), defined by subject matter experts. The proposed research investigates at the system level, safety-in-design of a reference SMR with passive and inherent design features (defense in depth included) such that assessment of off-site release of its radioactive inventory - the so-called source term is small, and forms the basis of defining its off-site release mechanism. This establishes the technical basis of the EPZ. In so doing, there is a need for a reference SMR, since many start-up designs are commercially protected (in detail). Yet the time evolution of low probability events is expected to be design-dependent. Further, since SMR will be utilized in unconventional and/or remote locations, the spectrum of unconventional threats (external, loss of electrical power etc.) needs re-evaluation. That is, the conservatism embedded in existing EPZ and linked evacuation plans also need review, relative to new applications. A revised, technical basis of defining the EPZ contributes to the Canadian and global nuclear knowledge base and contributes to regulatory harmonization. Finally, knowledge sharing and training of all inclusive stakeholders, via both traditional publications and existing social media platforms, advance nuclear energy, and enhance the level of acceptance and understanding of perceptions regarding nuclear energy and radiation science.