IEEE/IEC P63332-387

The alternating current (AC) power supply system performs a key safety function at nuclear facilities. The safety classified electric power system is essential for mitigating the consequences of accidents at facilities and preventing significant release of radioactive material to the environment. An onsite AC power source is required for supporting the safe shutdown of the facility in the event of loss of power from the external offsite sources. At nuclear power plants, the standby AC power source must be capable of providing the capacity and capability to assure that fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded for any anticipated occurrences, and the core is cooled and containment integrity and other vital functions are maintained in the event of postulated accidents. This requires the establishment of a reliable and robust power supply system that can be used to mitigate the consequences of postulated accident conditions. Important provisions in meeting this requirement are the principal design criteria, the design features, testing, and qualification requirements of the standby AC power source. Most nuclear power plants use diesel generators as standby AC power sources. This standard defines the requirements for the design of a robust standby AC power source that can be routinely tested to demonstrate operational capacity and capability. The standard provides design and testing requirements to demonstrate continuous load carrying capability and resilience to large load perturbations to ensure that diesel generators, used as standby AC power sources, have sufficient capacity, capability, and reliability to perform their intended function.