CFD analysis of passive autocatalytic recombiner interaction with atmosphere
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B. Gera
Abstract
In water cooled power reactors, significant quantities of hydrogen could be produced following a severe accident (loss-of-coolant-accident along with non availability of Emergency Core Cooling System) from the reaction between steam and zirconium at high fuel clad temperature. In order to prevent the containment and other safety relevant components from incurring serious damage caused by a detonation of the hydrogen/air-mixture generated during a severe accident in water cooled power reactors, passive autocatalytic recombiners (PAR) are used for hydrogen removal in an increasing number of French, German and Russian plants. These devices make use of the fact that hydrogen and oxygen react exothermally on catalytic surfaces generating steam and heat. Numerous tests and simulations have been conducted in the past to investigate passive autocatalytic recombiners behaviour in situations representative of severe accidents. Numerical models were developed from the experimental data for codes like COCOSYS or ASTEC in order to optimise the passive autocatalytic recombiners location and to assess the efficiency of passive autocatalytic recombiners implementation in different scenarios. However, these models are usually simple (black-box type) and based on the manufacturer's correlation to calculate the hydrogen depletion rate. Recently, uses of enhanced CFD models have shown significant improvements towards modeling such phenomenon in complex geometry. The work presents CFD analysis of interaction of a representative nuclear power plant containment atmosphere with passive autocatalytic recombiners simulated using the commercial Computational Fluid Dynamics code for PAR Interaction Studies (PARIS benchmarks) exercise. A two-dimensional geometrical model of the simulation domain was used. The containment was represented by an adiabatic rectangular box with two PAR located at intermediate elevations near opposite walls. The flow in the simulation domain was modelled as single-phase. The results of the simulations are presented and analysed.
Kurzfassung
In wassergekühlten Leistungsreaktoren können nach einem schweren Störfall (Kühlmittelverlust-Störfall zusammen mit der Nicht-Verfügbarkeit eines Notfall-Kernkühlsystems) erhebliche Mengen Wasserstoff entstehen durch die Reaktion zwischen Dampf und Zirkon bei hohen Temperaturen an den Brennstabhüllen. Um das Containment und andere sicherheitsrelevante Komponenten vor schweren Schäden durch eine Detonation des Wasserstoff-Luft-Gemischs, das bei schweren Störfällen in wassergekühlten Leistungsreaktoren entsteht, zu bewahren, werden passive autokatalytischer Rekombinatoren (PAR) für die Entfernung des Wasserstoffs verwendet in einer wachsenden Anzahl französischer, deutscher und russischer Kernkraftwerke. Diese Vorrichtungen machen sich die Tatsache zunutze, dass Wasserstoff und Sauerstoff auf katalytischen Oberflächen exotherm durch Erzeugung von Dampf und Wärme reagieren. Zahlreiche Tests und Simulationen wurden in der Vergangenheit durchgeführt, um das Verhalten passiver autokatalytischer Rekombinatoren in für schwere Störfälle typischen Situationen zu untersuchen. Aus experimentellen Daten wurden numerische Modelle für Rechencodes wie COCOSYS oder ASTEC entwickelt, um die Position passiver autokatalytischer Rekombinatoren zu optimieren und um die Effektivität des Einsatzes solcher Rekombinatoren in verschiedenen Szenarien zu bestimmen. Diese Modelle sind im allgemeinen einfach (Typ Black Box) und basieren auf den Herstellerangaben zur Berechnung der Wasserstoffabbaurate. Kürzlich hat die Verwendung erweiterter CFD-Modelle eine signifikante Verbesserung bei der Modellierung solcher Phänomene in komplexer Geometrie gezeigt. Die vorliegende Arbeit stellt CFD Analysen zur Wechselwirkung der Containment-Atmosphäre eines typischen Kernkraftwerks mit passiven autokatalytischer Rekombinatoren vor die mit dem kommerziell erhältlichen CFD Code für PAR Wechselwirkungsstudien (PARIS Benchmarks) durchgeführt wurden. Dabei wurde ein zweidimensionales geometrisches Modell der Simulationsregion verwendet. Das Containment wurde durch eine adiabatische, rechteckige Box mit zwei PAR dargestellt. Die Strömung in der simulierten Region wurde als ein-Phasen-Strömung modelliert. Die Ergebnisse der Simulationen werden vorgestellt und diskutiert.
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© 2011, Carl Hanser Verlag, München
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Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- Comparison between CAREB code calculations and LOCA test results in the FUMEX III project
- Calculation of moderator circulation in IPHWR using a porosity approach
- Simulation of natural circulation in a rectangular loop using CFD code PHOENICS
- CFD analysis of passive autocatalytic recombiner interaction with atmosphere
- Review and investigations of oscillatory flow behaviour of a horizontal ceiling opening for nuclear containment and fire safety analysis
- CFD simulation of thermal discharge behaviour in the Kadra reservoir at the Kaiga atomic power station
- Inverse problems using Artificial Neural Networks in long range atmospheric dispersion
- Sipping tests for the irradiated fuel elements of the TR-2 research reactor
- Neutron multiplication in source driven subcritical nuclear systems
- Cyclotron production of 101Pd/101mRh radionuclide generator for radioimmunotherapy
- Investigation of cross sections of reactions used in neutron activation analysis
- Modified UN method for the reflected critical slab problem with forward and backward scattering
