Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf
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Three-dimensional thermal-hydraulics analysis of ROCOM mixing experiment by RELAP5-3D© code
Frisani, A.; Del Nevo, A.; DAuria, F.; Höhne, T.; Kliem, S.; Rohde, U.
The mixing phenomenon is relevant for the normal and off normal operation of the Nuclear Power Plant (NPP), because it influences the safety, mitigating the reactivity and structural consequences. The study of these issues was investigated performing experimental campaigns in large-scale test facilities and in real NPPs. In this framework ROCOM (Rossendorf Coolant Mixing Model) test facility was built with the purpose of investigating the coolant mixing phenomena occurring in the Reactor Pressure Vessel (RPV) of a Pressurizer Water Reactor (PWR). The experiments executed in this facility provide experimental data for code validation (CFD and TH-SYS codes). The purpose of this work is to address the capability of the RELAP5-3D© to reproduce ROCOM facility dynamic in simulating the mixing for a large range of operational and accident conditions. In particular, the attention is focused on the effects in the vessel downcomer, lower plenum and core inlet. Three experiments were selected for the analyses: two steady states and one transient. The ROCOM steady states are slug mixing experiments that analyze the mixing scalar trend inside the facility at different mass flow rates. The ROCOM transient represents the injection of a mixing scalar slug from one cold leg with an increasing mass flow rate in the same loop. A systematic comparison between ROCOM experimental data and the results of the simulations with the RELAP5-3D© is presented including a complete set of sensitivity analyses to find out the most relevant parameters which influence the results from nodalization and user effects points of view.
Keywords: Mixing; RELAP5-3D©; ROCOM facility; code assessment
Contribution to proceedings
NURETH-12 - International Topical Meeting on Nuclear Reactor Thermal Hydraulics, 30.09.-04.10.2007, Pittsburgh, USA
CD-ROM, paper 159