PTS-2 test facility

The PTS-2 scale model was made of a metal rod, 150 mm thick, heated on one face, and inserted on its other face in a 300 x 100 mm² rectangular fluid channel. In the transverse direction, the distance is 100 mm. Lateral walls of the fluid channel are insulated with rockwool. The heater block consisted of a flat aluminum bar and six heater rods with a nominal heating power of 1 kW each. The mock-up (PTS-2) was connected to an auxiliary flow system, which provided the desired flow conditions. The test facility was equipped with 46 temperature, two differential pressure, two flow rate measurements and one level transmitter.

To evaluate the heat transfer characteristics at reactor pressure vessel (RPV) wall related to pressurized thermal shock (PTS) in cold leg emergency core cooling (ECC) injection 19 tests were carried out with the PTS-2 test rig at LUT in March–June 2017. During the test series three different water inlet temperatures (20, 40 and 70 °C) and flow rates (4, 17 and 34 kg/s) were tested. CFD analyses were performed to support the planning and set-up of tests. PIV (Particle Image Velocimetry) was used for measuring flow profile in the flow channel. Matlab scripts were developed to solve inverse heat transfer problems.

All together 16 tests were carried out after a series of pre-tests in April–September 2018. The test programme consisted of two parts:

1. Tests with low flowrates and natural convection. Tests were carried out similarly as the tests in 2017, but at a lower flow rate.
2. Tests with water film and free surface. The deflector was used and the flow channel was initially empty of water. Video cameras were used to assess the water film thickness.