To clarify thermal hydraulic behavior of the European Pressurized Reactor (EPR) core catcher design, a scaled down test rig was designed and constructed at Lappeenranta University of Technology (LUT) in 2004 (Volley 2004). The test rig consists of two full-scale horizontal, 5 m long (cross-section 50x100 mm) cooling channels made of cast iron (EN-GJL-150). The heat from molten corium is simulated with 68 cartridge heaters, mounted inside the upper part of the core catcher plate. The heaters are 180 mm long (the width of the core catcher plate), have a diameter of 20 mm and maximum heating power of 2.2 kW each. The maximum heat flux in the core catcher plate is approximately 160 kW/m². The coolant is drained by gravity from the boron solution tank (total volume 2.4 m³) down to the cooling channels.
The test facility is equipped with dozens of temperature, three pressure and two flow rate measurements. Additional instrumentation includes the measurements of heating power of the cartridge heaters. During the experiments flow pattern in the cooling channel can be recorded with four video cameras through the viewing windows.
In the Volley 2004, the top of the outflow pipe construction was connected to the atmosphere. In the EPR plant conditions this kind of test facility construction simulates the events in the early phase of a possible core melt accident i.e. water level in the spreading compartment is raising but stays still below the top of the sidewall cooling elements.
In 2005, the Volley facility was equipped with a buffer tank in the outflow pipe (Volley 2005). After this modification, the test rig construction simulates the events later after melt spreading in the core catcher area i.e. the spreading compartment is filled with water above the top of the sidewall cooling elements.
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