Large-Scale Containment Cooler Performance Experiments under Accident Conditions

Abstract

Computational Fluid Dynamics codes are increasingly used to simulate containment conditions after various transient accident scenarios. This paper presents validation experiments, conducted in the frame of the OECD/SETH-2 project. These experiments address the combined effects of mass sources and heat sinks related to gas mixing and hydrogen transport within containment compartments. A wall jet interacts with an operating containment cooler located in the middle (M-configuration) and the top (T-configuration) of the containment vessel. The experiments are characterized by a 3-phase injection scenario. In Phase I, pure steam is injected, while in Phase II, a helium-steam mixture is injected. Finally, in Phase III, pure steam is injected again. Results for the M-configuration show helium stratification build up during Phase II. During Phase III, a positively buoyant plume emerging from the cooler housing becomes negatively buoyant once it reaches the helium-steam layer and continuously erodes the layer. For the M-configuration, a strong degradation of the cooler performance was observed during the injection of the helium/steam mixture (Phase II). For the T-configuration, we observe a mainly downwards acting cooler resulting in a combination of forced and natural convection flow patterns. The cooler performance degradation was much weaker compared with the M-configuration and a good mixing was ensured by the operation of the cooler.

Large Scale Experiments Representing a Containment Natural Circulation Loop during an Accident Scenario

“…PANDA is a large scale thermal-hydraulic facility designed to investigate containment system behavior and related phenomena for different ALWR designs, e.g., SBWR or ESBWR as well as for large scale separate effect tests. PANDA was used in the past for various investigations, Kelm et al [6]; Kapulla et al [7,8]; Paladino et al [9]; Papini et al [10]; Visser et al [3]; Filippov et al [11]. The overall height of the PANDA facility is 25 m, the total volume of the vessels is about 460 3 , and the maximum operating conditions Figure 2: Different views of the four PANDA vessels illustrating the configuration and the pipes between the vessels as used for the HP6 series.…”

Effect of new drywell cooler application for venting start time during severe accidents

“…It has been recommended that existing drywell coolers (DWC), which are regular equipment to be conditioning gas temperature in the drywell (D/W) during a normal operation, be used for steam condensation as additional PCV cooling methods for an accident management during a severe accident. The condensation heat transfer rates with non-condensable gases (NCG) of the existing DWC (Yokobori et al, 2003) and the DWC with the duct (Kapulla, et al, 2012) were measured. If the DWC worked during a severe accident with steam generation, the DWC would contribute to mitigation of PCV pressure increase.…”