Managing Aging of Coatings for Nuclear Power Plant License Renewal

Coatings are applied to structures and components in nuclear power plants, both inside and outside containment. The coatings applied to safety-related structures, systems, and components inside containment are classified a Service Level I Coating, and coating systems outside of primary containment, but which in the event of a failure could adversely affect the orderly and safe shutdown of the plant are classified a Service Level III coating. Weaknesses have been found in existing programs in regards to application of protective coatings for Service Level 1. This weakness is evident as blistering, cracking or peeling. For the extended period of operation, the licensee must demonstrate that in-place coating is qualified except for coatings shown on an Unqualified Coatings List; that the amount of unqualified coatings will not clog sump screens, strainers, or other safety-related equipment; and that coating assessment is being made at each refueling outage. This paper will discuss the elements of a good coating program for the period of extended operation to ensure that existing coating systems are qualified; and that unqualified and degraded coatings will not clog strainers, screens or other safety-related equipment.