March 6 - 8, 2017 | Berlin
LEADING ENGINEERING SIMULATION CONFERENCE
In nuclear energy, many studies are dedicated to the simulation of accidents in order to prevent them and avoid severe consequences. Concerning fire modeling, the classical tools are “zone tools” that model the domain by 0D systems which is very efficient for small building.
One challenge is the modeling of conventional fire with up-to-date CFD tool able to model 3D large building and put forward the physical understanding. Main goals of CFD fire calculation are the ability to evaluate fire propagation in large buildings with complex geometries, the calculation of relevant 3D temperature field and the analysis of local thermal loads on strategic structures. AREVA NP has set-up a methodology to model fire propagation in large plant using STAR-CCM+® CFD tool. Technically, this method is based on the injection of hot gas in a defined area of the building which represents the energy source of the combustion. The fire propagation is evaluated by the tool taking into account heat transfer by convection and radiation.
The method has been validated on some experimental test cases. The first test case comes from the NIST (National Institute of Standard and Technology) and is considered as the reference case used for the validation of all the tools modeling fire. A second validation test case is a case set-up by IRSN (French nuclear safety authority engineering services). A benchmark of AREVA methodology has been performed with ISIS (IRSN conventional fire tool) and FDS (reference international fire tool developed by the NIST). The validation results are satisfying with a level of modeling higher than other tools taking benefit of the capacity of STAR-CCM+ (in particular concerning the radiation modeling not taken into account precisely in other tools). The tool is now used at an industrial scale by modeling fire propagation in large buildings on nuclear plants.