Abstract:

In this paper a comparison of the thermal-fluid analysis code Flownex with experimental data from the Pebble Bed Micro Model (PBMM) is presented. From the measured data it became clear that there were substantial heat losses from the turbines and the associated support structure as well as from the pressure vessel to the ambient. The original Flownex model was improved to account for these heat transfers. The new Flownex model was then used to simulate a mass injection transient test done on the PBMM.

In order to do proper simulation it is necessary to understand and quantify all the processes taking place in the plant. This is difficult when complex geometries are being modeled and when components are installed in different conditions than the conditions under which they were tested and characterized. Keeping these limitations in mind, good agreement between the experimental and simulation results was obtained.