I. PURPOSE AND SCOPE

No substantial maintenance has been performed on the cathodic protection system since 1984. Although this system is not required for plant operation, its proper operation is important in reducing long term corrosion of the metallic components of the circulating water system and other plant metallic equipment. In addition to the circulating water system, the cathodic protection system is intended to protect stack and off-gas piping, service water piping, the service water intake structure, and sewage treatment plant equipment.

The obsolete cathodic protection rectifiers will be replaced as part of the project. Also, a comprehensive cathodic protection system inspection will be performed to determine the extent of system degradation and required repairs. For example, some restoration of corroded junction boxes and supports will be required, and degraded conduits will have to be uncovered even if in concrete. In addition, divers will replace damaged or missing anodes and will assist in the repair of cathodic protection cables in the service water and circulating water intake pump bays. Some additional difficulty is expected since accurate drawings of the system are not available.

A restored and well maintained cathodic protection system will inhibit further degradation of the service water and circulating water system intake equipment exposed to the plant salt water environment. Reliable cathodic protection system operation will minimize the possibility of catastrophic failures of metallic supports, structures, and other equipment and will extend equipment operating lives.

II. EVALUATION

Schedule Index: 10 - Anticipated failures from excess corrosion would not prevent basic system function or present significant safety challenges. However, extension of circulating water system life represents a substantial plant enhancement (1.0 x 8). Without the restoration of the cathodic protection system, avoidable equipment replacements could extend an outage and reduce unit availability (0.2 x 12).

Economic Aspects: Once the system is restored to operability, some increase in routine effort will be required to perform system inspections and maintenance. Estimates of long-term savings due to corrosion reduction for protected components.

Related Standards: The applicable Work Management Policy is material condition.

Other Considerations: About twenty percent of the work requires unit outage.

III. CONCLUSION

This project is important to prevent unnecessary degradation of the circulating water system and will be accomplished as scheduled.