The containment is the third safety barrier in a nuclear power plant. It includes the containment structure and all penetrations through the containment. To ensure that the containment maintains its integrity during normal operation and in the event of an accident, preventing the release of radioactive materials, it is necessary to perform tests to verify its tightness. Based on the operational experience of the nuclear industry, the requirements for containment penetration tests provide minimal safety benefits. This article summarizes the method for extending the test intervals for containment penetrations, and provides an example for the interval extension of the Emergency Core Cooling System. The results show that the risk of interval extension can be ignored. Nuclear power plants can adopt this method to extend the interval of containment penetration tests, so as to improve the economy of the power plant under enough safety condition.