Experimental Investigation on Measuring the Leakage Rate of Nuclear Power Plant Containment by Pressure Drop Method

In order to further explore the basic law that the environmental conditions in the nuclear power plant containment affect the leakage rate measurement, a data analysis program for measuring the containment leakage rate by the pressure drop method was developed in this investigation. The measurement results were validated by leakage rate measurement tests carried out on a large-scale containment simulant. Based on the test data, the effects of the temperature and relative humidity on the leakage rate measurements under quasi-steady-state and non-steady-state conditions were studied. The results show that in the heating environment, the different heating rates of each temperature sensor due to the difference in the thermal environment can significantly affect the measurement of the leakage rate, and the relative deviation of the measured value compared with the temperature before heating can exceed 20%. Moreover, in the unsteady environment of local temperature and humidity changes in the vessel, the inherent delay effect of the pressure and temperature sensors can also cause abnormal leakage rate measurements. However, when the temperature and humidity in the casing are kept constant or the temperature and humidity change rates of each sensor are approximately the same, the measured value of the leak rate is relatively stable. The conclusions provide a reference for further understanding the leakage rate measurement mechanism and method optimization.