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Science and Technology of Nuclear Installations
Volume 2009 (2009), Article ID 583259, 13 pages
Project Report

An Overview of the Pressurized Thermal Shock Issue in the Context of the NURESIM Project

1Forschungszentrum Dresden-Rossendorf, e.V. (FZD), Institute of Safety Reseach, P.O. Box 510 199, 01454 Dresden, Germany
2Commissariat à l'Énergie Atomique (CEA), Centre d'Études Nucléaires de Grenoble, 17 Rue des Martyrs, 38054 Grenoble, France
3Gesellschaft für Anlagen- und Reaktorsicherheit mbH(GRS), 85748 Garching, Germany
4Dipartmento di Ingengeria Meccanica, Nucleare e della produzione, Università di Pisa, Via Diotisalvi 2, 56126 Pisa, Italy
5Paul Scherrer Institute, 5232 Villigen-PSI, Switzerland
6Jožef Stefan Institute (JSI), 1000 Ljubljana, Slovenia
7Fluid Dynamics Power Generation Department, Recherche et Développement, Électricité de France (EDF), 6 quai Watier, 78400 Chatou, France
8ASCOMP GmbH, Technoparkstrass 1, 8005 Zurich, Switzerland
9Université Catholique de Louvain La Neuve (UCL), Place du levant.2, 1348 Louvain-La-Neuve, Belgium
10Lappeenranta University of Technology (LUT), Skinnarilankatu 34, 53851 Lappeenranta, Finland
11VTT Industrial Systems, PL 1000, 02044 VTT, Finland
12Nuclear Research Institute Rez plc (NRI), Husinec-Rez 130, 25068 Rez, Czech Republic

Received 14 January 2008; Accepted 21 February 2008

Academic Editor: Yassin Hassan

Copyright © 2009 D. Lucas et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Within the European Integrated Project NURESIM, the simulation of PTS is investigated. Some accident scenarios for Pressurized Water Reactors may cause Emergency Core Coolant injection into the cold leg leading to PTS situations. They imply the formation of temperature gradients in the thick vessel walls with consequent localized stresses and the potential for propagation of possible flaws present in the material. This paper focuses on two-phase conditions that are potentially at the origin of PTS. It summarizes recent advances in the understanding of the two-phase phenomena occurring within the geometric region of the nuclear reactor,that is, the cold leg and the downcomer, where the “PTS fluid-dynamics" is relevant. Available experimental data for validation of two-phase CFD simulation tools are reviewed and the capabilities of such tools to capture each basic phenomenon are discussed. Key conclusions show that several two-phase flow subphenomena are involved and can individually be simulated at least at a qualitative level, but the capability to simulate their interaction and the overall system performance is still limited. In the near term, one may envisage a simplified treatment of two-phase PTS transients by neglecting some effects which are not yet well controlled, leading to slightly conservative predictions.