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NKS Programme Area: | NKS-R | Research Area: | Severe accidents | Report Number: | NKS-314 | Report Title: | A study on the coolability of debris bed geometry variations using 2D and 3D models | Activity Acronym: | DECOSE | Authors: | Eveliina Takasuo, Veikko Taivassalo, Ville Hovi, | Abstract: | In the first and second parts of the present work, the coolability of porous debris beds with different geometries (spatial distributions) has been assessed by using 2D and 3D simulation methods. The 2D simulations were conducted with the MEWA code by Stuttgart University. The 3D simulations were performed with the commercial CFD code Fluent, after the implementation of the porous media models as user defined functions into the code. The focus of the MEWA simulations was on the following multi-dimensionally flooded debris bed geometries: fully flooded cylinder (open sidewall and top), laterally flooded cylinder (open sidewall) and the cone on a closed cylindrical base. These geometries comprise the COOLOCE experimental series 10-12. In the Fluent simulations, the focus was on the verification of the model implementation, comparisons to MEWA results and the extension of the modelling approach to full 3D. Full 3D calculations were conducted for the conical test bed. In the third part, an insight into the uncertainty in the experimental determination of DHF is provided. Experiments with a top-flooded bed have been conducted with the COOLOCE facility at VTT and the POMECO facility at KTH with the same particle material. The comparisons revealed the effect of the non-modifiable part of the test set-up such as the heating and instrumentation systems. | Keywords: | severe accident, debris bed, coolability, numerical simulation, CFD | Publication date: | 17 Jun 2014 | ISBN: | ISBN 978-87-7893-393-5 | Number of downloads: | 2834 | Download: | NKS-314.pdf |
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