The containment is designed to contain radioactive materials, protect the public from radiation, and shield it from external events during normal operations and accident conditions. To verify the construction quality and evaluate containment leak tightness performance under accident conditions, a containment Integrated Leak Rate Test (ILRT) should be performed periodically. ILRT occupies the critical path of commissioning and refueling, which can seriously affect the NPP’s economics. At present, a large number of NPPs in the U.S. have extended the ILRT intervals to 15 years based on a risk-informed containment performance evaluation method. However, in China, the current ILRT interval is 10 years, and relevant studies on intervals extension are still in the development stage. Therefore, this study focused on identifying significant risk indicators, which is the first step in performing a risk-informed ILRT intervals extension. In this study, first, some domestic and foreign research and practices on ILRT intervals extension are investigated, especially the analysis of requirements and regulations, which are used to demonstrate whether the ILRT intervals for Chinese NPPs could be extended. Second, the risk-informed methodology, identification process, and results of significant risk indicators were investigated for the risk-informed ILRT intervals extension. Finally, the conclusions regarding to significant risk indicators and the outlook of intervals extension applications are discussed for further study.