HEAT TRANSFER ASSESSMENT OF THE COSMEA TEST FACILITY COOLING SIDE

Reliable performance of passive safety systems – which function using physics laws without external interventions during an accident- is an important issue with respect to nuclear power plant (NPP) safety. Investigation of thermal behavior and the operational stability of passive safety systems in Generation III and III+ nuclear reactors is the objective of the project PANAS (PAssive Nachzerfallswärme-AbfuhrSysteme – Passive Residual Heat Removal System) funded by the German Federal Ministry of Education and Research (BMBF). In this context, experiments are being performed in the high-pressure COSMEA test facility at HZDR (Helmholtz Zentrum Dresden Rossendorf) to assess the emergency condenser (EC) based on the KERENATM boiling water reactor. The objective of this work is to complement previous efforts in PANAS project related to the primary side heat transfer coefficient with the focus on the heat transfer assessment of the secondary side. The assessment of state-of-the-art heat transfer models is presented in this paper, and it shows that they often fail to predict the heat transfer behavior of the secondary side recorded at the COSMEA facility. Therefore, to consider different factors influencing the cooling capacity, it is required to have an accurate simulation of the process. In this regard, a 3D CFD simulation of the COSMEA secondary side with ANSYS CFX is carried out in this study to show the temperature gradient of the flow and heat transfer performance of the system. The results of the heat transfer coefficients calculated by CFX codes have a good agreement with experimental data of the COSMEA facility.