Daniel K. Inouye Solar Telescope system safety

System safety for the Daniel K. Inouye Solar Telescope (DKIST) is the joint responsibility of a Maui-based safety team and the Tucson-based systems engineering group. The DKIST project is committed to the philosophy of “Safety by Design”. To that end the project has implemented an aggressive hazard analysis, risk assessment, and mitigation system. It was initially based on MIL-STD-882D, but has since been augmented in a way that lends itself to direct application to the design of our Global Interlock System (GIS). This was accomplished by adopting the American National Standard for Industrial Robots and Robot Systems (ANSI/RIA R15.06) for all identified hazards that involve potential injury to personnel. In this paper we describe the details of our augmented hazard analysis system and its use by the project. Since most of the major hardware for the DKIST (e.g., the enclosure, and telescope mount assembly) has been designed and is being constructed by external contractors, the DKIST project has required our contractors to perform a uniform hazard analysis of their designs using our methods. This paper also describes the review and follow-up process implemented by the project that is applied to both internal and external subsystem designs. Our own weekly hazard analysis team meetings have now largely turned to system-level hazards and hazards related to specific tasks that will be encountered during integration, test, and commissioning and maintenance operations. Finally we discuss a few lessons learned, describing things we might do differently if we were starting over today.