Degradation of buried metallic piping from corrosion is a significant issue facing owners and operators of nuclear power plants. This paper discusses the results of a major cathodic protection (CP) system upgrade project for buried piping and underground storage tanks at a nuclear power plant in South Carolina. To provide for effective CP the design engineer needed to take into account the requirement for higher current demand the location of electrical grounding reinforced concrete foundations bare or poorly coated structures uniform current distribution depth to bedrock anode bed configuration structure connections test station type and location close interval survey test results rectifier design system operation and maintenance. The database for the system is incorporated into a mapping visualization program so the system engineer can effectively monitor and trend the CP system performance. Criteria for effective CP in grounded mixed-metal piping systems is also discussed.