Building a Body of Knowledge to Inform a Technology-Agnostic Iterative Safety Assessment Methodology for Fusion Facilities

Recent years have seen the achievement of important milestones in the harnessing of fusion energy for potential commercial applications. However, even ambitious timelines place the commissioning of a commercial pilot plant at least a decade away. The path to commercialization will involve the development of a commercially viable design, featuring a robust safety and reliability case that (1) comprehensively characterizes system safety, (2) facilitates regulator interactions via industry standard analytical methods, and (3) can build confidence with potential stakeholders. This path benefits from fusion not being burdened with some of the hazards associated with fission (e.g. criticality, decay heat), and therefore lends itself to a “clean slate” approach to design and safety assessment. The Electric Power Research Institute (EPRI) and Vanderbilt University (VU) have demonstrated a technology-neutral safety-in-design (SiD) methodology that incorporates risk and reliability considerations into each stage of the design, thereby incrementally building the safety and reliability case for a technology. The SiD methodology was originally developed for assessing early-stage advanced fission reactors, addressing challenges associated with limited operational experience, unfamiliar systems, and unique radiological, chemical, and other industrial hazards, thus supporting a technology-agnostic, flexible approach. The SiD methodology leverages established qualitative and semi-quantitative process hazard assessment methods, offering a practical means for developing the building blocks for quantitative risk assessment (if needed), and supports efficient early engagement with regulators. EPRI and VU, with fusion community members, utilities, and regulators, are evaluating the application of the SiD methodology to fusion technology. This paper presents an initial outline of a body of knowledge (BoK) that identifies and categorizes papers, reports, and technical standards reflective of academic and industry efforts in topical areas related to fusion safety and reliability. BoK development is a common approach to capture and describe the state of the art in a technical domain; for example, the BoK process has been used to perform the initial organization of the state of the art in areas such as systems engineering, environmental engineering, and project management. Here, BoK development is intended to provide the fusion community with access to a compendium of technical information to draw on during design, safety analysis, and early engagement with regulators and stakeholders. To date, more than 100 documents have been identified to form the BoK for the SiD application to commercial fusion plants. We have presently organized this documentation into seven topical areas: (1) a description of fusion technologies, (2) previous fusion safety analyses, (3) reliability studies, (4) safety analysis insights from nonfusion facilities, (5) fusion regulation and relevant technical guidance, (6) safety, environment, fuel cycle, and decommissioning studies, and (7) commissioning and operation studies. Preliminary engagement with the fusion community indicates that the SiD approach can inform and support fusion technology developers seeking to mature commercially relevant designs and build robust safety and reliability cases for technologies in an environment characterized by evolving regulatory regimes and limited operational experience.