Experimental study of the air–steam mixture leakage rate through damaged and partially saturated concrete
Résumé
This study is focused on the tightness of containment walls of nuclear power plants in case of loss of coolant accident. This kind of accident results in the rise from ambient conditions to a temperature of 140 °C and an air–steam mixture pressure of 5.2 bars. This rise creates high hydric, thermal and mechanical stress in concrete, impairing the tightness integrity of concrete wall. In this work, we propose to highlight experimentally the influence of initial water content of the sample, the compressive load and the percolating fluid on the hydraulic behavior of concrete. The tests are carried out on hollow cylindrical samples, using a device which allows to generate a gas mixture at the inlet and to measure the leakage rate at the outlet of the samples. As the tests are performed in isothermal conditions, the results show that at stress levels lower than 70–80 % of the peak stress, the leakage rate of the mixture is slightly influenced by both parameters (degree of saturation and stress). However, it can be noted that as the load exceeds this threshold value, the damage effect due to mechanical loading remains more important in the leakage rate evaluation.
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