Research on Airtightness Test of Habitable Zone in Main Control Room of HPR1000

Based on the constant flow method, research was conducted on the airtightness test of the habitable area in the main control room from multiple dimensions such as test method selection, tracer gas injection, sampling method, equilibrium concentration, and calculation of test results. Improvements and applications were made to the K2/K3 unit of the Karachi nuclear power project. The results showed that by studying the factors affecting the uniformity of tracer gas mixing, the relationship between positive pressure and internal leakage was determined, and the ideal positive pressure value for conducting the experiment was approximately 50 Pa; By studying the relationship between positive pressure and air volume difference, it was found that the ideal positive pressure range for conducting the experiment is 35~50 Pa; By analyzing the relationship between positive pressure and internal leakage, the ideal positive pressure value for conducting the experiment was obtained; On this basis, through comparative analysis of tracer gas concentration data, the fluctuation amplitude and pattern of concentration were analyzed, and effective measures to promote tracer balance were proposed. That is, adding mixed flow equipment can make the tracer gas concentration fully uniform and reduce the fluctuation amplitude of concentration.