Application of hazard and operability analysis for safeguardability of a pyroprocessing facility

Pyroprocessing treats nuclear fuel using electrochemical techniques for a variety of applications, whether to process used uranium oxide fuel for back-end management, or to reprocess used metallic fuel for an advanced fuel concept. Since there are proliferation risks associated with special nuclear material (SNM) processed in a pyroprocessing facility, the high reliability safeguards (HRS) methodology has been developed to implement safeguards, safety, and physical security (3S) together with operations from a design-driven perspective. This paper suggests the design strategies by integrating a hazard and operability (HAZOP) analysis. It is a process hazard analysis, essential for identifying hazards, operability issues, severe accident scenarios, and for mitigating consequences with the corresponding protection methods. It is a preliminary step for an eventual quantitative, probabilistic risk analysis, which may be needed for obtaining an operating license for a commercial pyroprocessing facility. The focus of this HAZOP analysis was on major pyroprocessing subsystems; voloxidation, electroreduction, electrorefining, electrowinning, and the argon atmosphere control system. Deviations were analyzed from normal operating conditions, and methods were thoroughly prepared to prohibit or mitigate off-normal situations. Importantly, pressure buildup or high temperature in the systems can increase the risk of initiating fire/explosion, which may eventually release radiation to the outside. Safety relief valve installations, valve actuation and heater automatic shutdown systems, etc., would be helpful to alleviate operational problems. This enhanced HAZOP also suggests a strong safeguards design for the facility by proposing nuclear material accounting (NMA) locations for the purpose of reducing potential proliferation risks.