CSNI Workshop

Benchmarking of CFD Codes for Application to
Nuclear Reactor Safety

Garching, Munich, Germany
5-7 September 2006

In co-operation with the International Atomic Energy Energy Agency (IAEA)
Hosted by Gesellschaft für Anlagen und Reaktorsicherheit (GRS)

This workshop was intended to provide a forum for numerical analysts and experimentalists to exchange information in the field of nuclear reactor safety (NRS) related activities relevant to computational fluid dynamics (CFD) validation:

  • CFD simulations with an emphasis on validation are welcome in areas such as: heat transfer, buoyancy, multi-phase flows, natural circulation, free-surface flows, turbulent mixing, and complex geometries. These should relate to NRS-relevant issues such as: pressurised thermal shocks, boron dilution, hydrogen distribution, induced breaks, thermal striping, etc. The use of systematic error quantification and best practice guidelines is encouraged.
  • Experiments providing data suitable for CFD validation, specifically in the area of NRS. These would focus on local measurements using laser-doppler velocimetry, hot-film/wire anemometry, particle image velocimetry, and laser-induced fluorescence. Papers should include a discussion of error bounds and measurement uncertainties.

Workshop background

The last decade has seen an increasing use of three-dimensional CFD codes to predict steady-state and transient flows in nuclear reactors. The reason for the increased use of multi-dimensional CFD methods is that a number of important phenomena such as pressurised thermal shocks, boron mixing, and thermal stratification cannot be predicted by traditional one-dimensional system codes with the required accuracy and spatial resolution.

CFD codes contain empirical models for simulating turbulence, heat transfer, multi-phase flows, and chemical reactions. Such models must be validated before they can be used with sufficient confidence in NRS applications. The necessary validation is performed by comparing model results against trustworthy data. However, in order to obtain a reliable model assessment, CFD simulations for validation purposes must satisfy strict quality criteria. For instance, numerical errors caused by too coarse numerical grids should be separated from shortcomings of the physical models to avoid wrong conclusions about model performance.

These requirements have prompted an NEA initiative to form a writing group of experts with the specific task of assessing the maturity of CFD codes for NRS applications, and to establish a data base and best practice guidelines for their validation. This workshop addressed these activities.

Organising Committee

Brian L. Smith, Paul Scherrer Institute, Switzerland, General Chair

John H. Mahaffy, Pennsylvania State University, USA, Co-Chair (Single-Phase)

Dominique Bestion, Commissariat à l'Energie Atomique, France, Co-Chair (Multi-Phase)

Martina Scheuerer , Gesellschaft für Anlagen-und. Reaktorsicherheit, Germany, Local Organizer

Suk-Ho Lee, International Atomic Energy Agency, Austria, Secretariat

Han-Chul Kim, OECD Nuclear Energy Agency, France, Secretariat

Scientific Committee

Ulrich Bieder, Commissariat à l’Energie Atomique, France
Philippe Dietrich, Institut de Radioprotection et de Sûreté Nucléaire, France
Franck Dubois, Institut de Radioprotection et de Sûreté Nucléaire, France
Estelle Graffard, Institut de Radioprotection et de Sûreté Nucléaire, France
Mats Henriksson, Vattenfall Utveckling AB, Sweden
Thomas Höhne, Forschungszentrum Rossendorf, Germany
Moonkyu Hwang, Korea Atomic Energy Research Institute, Korea
Ed Komen, Nuclear Research and Consultancy Group, Netherlands
Fabio Moretti, University of Pisa, Italy
Tadashi Morii, Japan Nuclear Energy Safety Organization, Japan
Petr Mühlbauer, Nuclear Research Institute, Czech Republic
Tadashi Watanabe, Japan Atomic Energy Research Institute, Japan
Ghani Zigh, United States Nuclear Regulatory Commission, USA


  • International Atomic Energy Agency;
  • Vattenfall;
  • Silicon Graphics Inc.;
  • CD-Adapco;
  • ANSYS Inc;
  • FLUENT; &
  • T-Systems.

Related links


Last updated: 18 September 2006


Detailed programme

Fourth announcement