Overview of the use of prestressed concrete in U.S. nuclear power plants

The evolution of containment systems in the United States is presented as well as motivations for changes. Prestressing systems and the mechanisms utilized for providing corrosion protection of these systems are reviewed. A summary of experiences and problems during construction of PCCs is presented. Results obtained indicate that the few construction problems which occurred were identified and remedied prior to a structure being placed in service. A review of regulatory requirements relative to inservice inspections of prestressing tendons is presented. The few incidences of problems or abnormalities that were identified in these inspections were found to be minor in nature and did not threaten the structural integrity of the containments. In conclusion, the frequency of occurrence of incidences which could lead to a decrease in the functional capability of PCCs is small, especially considering the number of PCCs in service in the United States. Where problems did occur, they generally were the results of construction practices, and were identified and corrected during either the construction phase, the initial structural integrity test, or in subsequent inservice inspections. Thus it can be concluded that the inspections have been effective in achieving their desired objectives of uncovering and correcting potential problem areas. (orig.)