Development of a Technology-Inclusive Methodology to Analyze the Environmental, Safety, and Health Risks Associated with Advanced Nuclear Reactor Designs as Demonstrated on the Molten Salt Reactor Experiment

Abstract

The development of a flexible methodology to comprehensively identify the hazards, and determine the most significant risks associated with the operation of advanced nuclear reactor designs, is required in order to systematically assess the safety of advanced nuclear reactors in general, along with their potential for environmental insult. Additionally, integration of appropriate safety and risk assessment methods into the design process can provide valuable insights and feedback early in the systems development process, when changes are less costly to make. A novel methodology, intended to be useful to begin the process of environmental, safety, and health (ES&H) risk assessment for early stage advanced reactor designs, was defined. The developed ES&H risk assessment approach was demonstrated using the Molten Salt Reactor Experiment design, a Liquid-Fueled Molten Salt Reactor (LF-MSR) design with minimal historical safety analysis documentation, in order to illustrate its flexibility and help build experience in the area of advanced reactor ES&H risk assessment. Tasks performed include: a systematic search for potential accident initiators; a detailed Failure Modes and Effects Analysis of a unique LF-MSR design feature; and the application of a risk-informed, performance-based evaluation of potential LF-MSR accident scenarios. The results demonstrate that, for nuclear facility safety analysis, a reliable method to achieve sufficiently thorough ES&H hazard identification is through the disciplined application of a proven hazard analysis/evaluation tool. More specifically, the use of Process Hazards Analysis (PHA) tools, even in early stages of design and technology development, was found to provide a more comprehensive and systematic approach to accident scenario development than relying simply on the use of historical research and propagation of past deterministic approaches to safety. In addition, these tools can also develop risk insights to inform an iterative approach to systems design and help identify priorities for necessary research and development.