WG_6.4 - Programmable Digital Computers to Safety Systems Working Group

Warren Odess-Gillett

This standard serves to amplify criteria in IEEE Std 603(TM), to address the use of programmable digital devices as part of safety systems in nuclear power generating stations. The criteria contained herein, in conjunction with criteria in IEEE Std 603, establish minimum functional, performance and design requirements for programmable digital devices used as components of a safety system.

This standard establishes the principles of analysis for and the documentation of the defenses provided against Common Cause Failure (CCF) of Electrical, Instrumentation and Control systems in nuclear facilities. It covers CCF from hazards and also from systematic faults. The standard does not provide requirements on detailed design or of acceptance criteria for the adequacy of CCF defense.

Additional computer specific requirements to supplement the criteria and requirements of IEEE Std 603-1998 are specified. Within the context of this standard, the term computer is a system that includes computer hardware, software, firmware, and interfaces. The criteria contained herein, in conjunction with criteria in IEEE Std 603-1998, establish minimum functional and design requirements for computers used as components of a safety system.

Additional specific requirements to supplement the criteria and requirements of IEEE Std 603(TM) are specified for programmable digital devices. Within the context of this standard, the term programmable digital device is any device that relies on software instructions or programmable logic to accomplish a function. Examples include a computer, a programmable hardware device, or a device with firmware. Systems using these devices will also be referred to as digital safety systems in this standard. The criteria contained herein, in conjunction with criteria in IEEE Std 603, establish minimum functional and design requirements for programmable digital devices used as components of a safety system