PANAS- Project: Heat Transfer Model Development for Passive Safety Systems

The Project PANAS (acronym for the German “PAssive Nachzerfallswärme-AbfuhrSysteme” = passive residual heat removal systems) deals with the assessment of the heat transfer mechanisms and the operational stability of passive residual heat removal systems applied in GENERATION III and III + nuclear reactors. The project is funded by the German Federal Ministry of Education and Research and executed by a consortium consisting of the German Partners: Technische Universität Dresden (TUD), Technische Hochschule Deggendorf (THD), Helmholtz Zentrum- Dresden- Rossendorf (HZDR), Framatome GmbH and PreussenElektra GmbH. Based on experimental data recorded during the course of the project at the high-pressure test facility COSMEA at HZDR and the low-pressure test facility GENEVA at TUD state of the art heat transfer models are examined. The test facilities are equipped with innovative two-phase-flow instrumentations and heat transfer probes. At the COSMEA test facility the angular resolved radial heat transfer measurement is combined with a 2D image of the liquid/vapor phase distribution inside a heat exchanger pipe. Since drastic deviations between experimentally obtained and calculated heat transfer have been detected depending on the operational conditions, available heat transfer models are modified or new models are proposed. This model adaptation and development process is supported by 3D CFD modeling of the flow inside the tubes. In addition, the operational stability of low-pressure natural circulation systems has been assessed applying RAM-ROM methodology. The paper gives an overview of the first project phase recently being completed and outlines the objectives of the subsequent project phase, which is planned to be completed until end of 2020.