(In)Consistencies Among Nuclear Facility Safety Analysis Terminology in the United States: An Exercise in Semantics or a Call for Consistency?

Within the United States, applicable rules and regulations related to the performance, documentation, and review of nuclear facility safety assessments are dependent on the ownership (e.g., commercially versus government owned) and nature (e.g., reactors, and front-end versus back-end of the fuel cycle) of the nuclear facility in question. In the United States, the nuclear facility regulatory framework has evolved over an extended time period; this has led to a set of standards, handbooks, and general guidance for documenting the performance of nuclear facility safety analyses that contain disjointed terminology. In addition to existing regulatory frameworks and safety analysis approaches, the U.S. Nuclear Regulatory Commission (NRC) and U.S. Department of Energy (DOE) are each in the process of independently developing new or revised risk-informed safety analysis/decision-making processes for nuclear facilities—independently. In cognizance of these near-term updates to options for nuclear facility safety analyses within the United States, the authors performed a limited-scope comparative analysis examining linguistic differences, and implications for safety assessment, of some of the most common safety analysis terminology used within the DOE and NRC contexts. We examine in detail deviations in terminology, definitions, and categorizations related to frequency binning and safety significance of controls and structures, systems, and components.Although substantial content similarities exist between these rules and guidance documents, the associated terminology definitions and implementations vary based on the ownership and nature of the nuclear facility, producing opportunities for miscommunication among even expert nuclear facility safety analysts, depending on the regulatory context within which their experience was gained. This conclusion, which should not be taken lightly when considering public perceptions of nuclear facility siting and deployment today, leads us to address the potential for terminology harmonization within the U.S. nuclear industry in order to improve public understanding of nuclear facility risks and benefits. Specifically, we discuss potential benefits afforded by terminology harmonization (e.g., improved ability to participate in risk dialogues), impediments and drawbacks to achieving harmonization (e.g., sector-specific legislation and federal regulations), and potential consequences of nonharmonization, including impacts on public confidence in nuclear safety analyses. With this in mind, we suggest potential options for improving the consistency of terms throughout the industry, such as partial or stepwise harmonization and the development of a nuclear safety terminology concordance.