INFLUENCE OF THE POSITION AND NUMBER OF DECAY HEAT-EXCHANGERS ON THE THERMAL-HYDRAULICS OF A SLAB TEST FACILITY - A COMPARISON OF ANALYTICAL AND EXPERIMENTAL-DATA

To assess the capability of passive decay heat removal systems of an a dvanced pool-type liquid-metal cooled reactor, natural circulation exp eriments have been performed to investigate the in-vessel cooling mode s caused by the position and number of decay heat exchangers in operat ion. The rather simple slab test facility AQUARIUS is equipped with an electrically heated core and decay heat exchangers. Four different ar rangements of heat exchangers are under consideration to study the tem perature distribution and the flow behavior in the apparatus during bo th symmetrical and asymmetrical heat removal. The experiments have bee n carried out in water under laminar flow conditions. Temperatures hav e been measured under quasi-steady-state conditions. The observed flow paths have been documented photographically. In case of asymmetrical heat removal, especially when a single heat exchanger is operated in o ne of both upper plena, the temperature distribution and the flow beha vior are different from symmetrical cooling modes. A comparison of ana lytically predicted temperatures using the COMMIX-2(V) computer progra m with experimental data shows reasonably matches the findings. The re sults of the numerically determined velocity fields are in good agreem ent with the visual observations.