THE EFFECTS OF A NON-CONDENSABLE GAS ON PRESSURIZER INSURGE TRANSIENTS UNDER THE HIGH PRESSURE

The prediction of the pressurizer response during various transients plays an important role in determining what actions should be taken to control or mitigate the consequence of an accident. For this reason, a range of different experiments have been completed which aim to support a preliminary understanding of the phenomena which are important to the analysis of a PWR pressurizer. As so far, the researches on these subjects are focusing on the low pressure, there are rarely researches on the high pressure. Hence, the effects of a non-condensable gas on pressurizer insurge transients under high pressure are necessary and significant. The study concentrates on the pressure response and heat transfer during an insurge transient under the high pressure. These experiments were run in two cylindrical stainless steel tanks: the primary tank and the storage tank. In this research, the experiments looked at the effects of water level increase and the presence of a non-condensable gas with varying mass fraction. Nitrogen was chosen as the non-condensable gas. The storage tank was filled with water and pressurized with nitrogen. An insurge to the primary tank with hot walls was initiated by opening the high pressure solenoid valve between two tanks. The experiments assigned lots of thermocouples for monitoring the radial and axial temperature distribution. Experiments showed that the non-condensable gas has a substantial influence on the pressure response. And the magnitude of the increase in peak pressure is quite different with the change of experiment initial conditions.