The PASTELS PASI test campaign at LUT University, Lappeenranta, Finland started in March 2022 with the first test, which investigated the effect of loop friction on the open loop flow behavior and heat transfer from containment to the loop. The test was successfully conducted, showing an oscillative loop flow behavior as expected. The downcomer massflow rate is presented in the figure below.
The figure shows how the flow behavior depends on the flow resistance, which was executed by means of closing the shutoff valve in the downcomer line. During the experiment, quasi-steady states were run with six different valve positions starting with the valve fully open. The heat removal loop was able to transfer heat efficiently from the containment vessel to the heat sink and to keep the containment vessel pressure within a safe level. This shows that an oscillating flow can be an efficient heat removal mechanism.
