Application of Power Function Model of Gas Leakage in Tightness Test of Double-wall Containment Annulus

The tightness of the annulus of the nuclear power unit with double-wall containment is an important guarantee of nuclear safety, which needs to be tested before the unit is loaded. The power function model of gas leakage has a wider range of pressure application and higher accuracy than the quadratic function model for calculating the leakage of civil buildings. In this paper, based on the power function model of gas leakage, the calculation model of annulus leakage rate and the power function fitting scheme with annulus negative pressure correction are derived, and the calculation model is verified by the measured data of a double-wall containment annulus tightness test. The results show that the calculation model in this paper has higher accuracy than the quadratic function fitting scheme with annulus negative pressure correction and the linear fitting scheme used by a foreign company, and is more consistent with the actual leakage of double-wall containment.