Parameter study at the PKL test facility on heat transfer mechanisms in the steam generator in presence of nitrogen, steam and liquid

PKL is a worldwide unique integral test facility for simulation of thermal-hydraulic phenomena, which can occur in Pressurized Water Reactor under abnormal or accident conditions. The test rig replicates the entire primary side and the relevant parts of the secondary side of western-type PWR plant in the scale of 1:1 in heights and 1:145 in volume and power. The analyses that have been carried out for the last 40 years have always reflected safety issues addressed in the debate of nuclear community. Among goals of experimental programs conducted at the facility there are demonstration of safety margins, investigation of thermal-hydraulic behavior of a plant under accident conditions, verification of accident management procedures as well as provision of data for thermal-hydraulic codes validation. This paper provides a detailed analysis of experiment dedicated to investigation of heat transfer mechanisms in steam generator in presence of non-condensable gas, steam and liquid. Such conditions can occur in a PWR in case of loss of residual heat removal system under cold shutdown conditions. Probabilistic safety assessments indicated that this accident contributes to much larger core damage frequency than originally anticipated. Therefore, an increasing attention has been paid to this accident scenario in the recent years.