To ensure safe operation of the United States’ nuclear power plants, the Nuclear Regulatory Commission enacted 10CFR50.55a(b)(3)(xi) requiring the verification of valves’ capability to control plant process conditions. Palo Verde Generating Station implemented the requirement with a focus on crediting existing operational and testing activities, iterating to optimize implementation. The station credits valve diagnostics, operational activities, and component testing programs wherever possible. Where testing and operations are insufficient to meet the requirement, phased-array ultrasonic equipment is used to verify stem-disc connection integrity. Palo Verde is fully compliant with the requirements of 10CFR50.55a(b)(3)(xi). This suggests compliance at other pressurized water reactors can be achieved primarily by documenting existing plant activities with minimal new testing activities required.

This content is only available via PDF.