Regulatory Aspects of Containment Leakage Testing

Abstract

The containment system of a nuclear power plant provides the final barrier between the principal source of radioactivity in the plant and the world outside. It controls any accidental releases of radioactivity from the reactor system while it protects the reactor and principal components from potentially damaging outside influences such as tornados. A leakage testing program for the containment as a whole and for its many component penetrations and isolation valves is conducted periodically to check the degree of its leaktight integrity. There are a few important existing and pending documents that define, regulate, and describe this testing program. These are the Nuclear Regulatory Commission's 10 CFR Part 50, Appendix J, the NRC's pending regulatory guide MS 021-5, the American National Standards Institute standard ANSI/ANS 56.8, and a draft industry leakage rate testing program. This paper discusses these documents , their status and relationship to each other, and the benefits that their sponsors intend should result from their use. These documents have evolved because the containment system leakage rate testing program is of considerable interest to both regulators and the nuclear power industry. To the regulators, it represents a means of assurance for the public that the containment system would respond as designed if needed under design accident conditions. To the nuclear power industry, it also serves as an inservice inspection program to determine if maintenance resources are being efficiently used to keep the containment system functional at all times at its intended design level.