Equilibrium based analytical model for estimation of pressure magnification during deflagration of hydrogen air mixtures
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A. Karanam
Abstract
During postulated accident sequences in nuclear reactors, hydrogen may get released from the core and form a flammable mixture in the surrounding containment structure. Ignition of such mixtures and the subsequent pressure rise are an imminent threat for safe and sustainable operation of nuclear reactors. Methods for evaluating post ignition characteristics are important for determining the design safety margins in such scenarios. This study presents two thermo-chemical models for determining the post ignition state. The first model is based on internal energy balance while the second model uses the concept of element potentials to minimize the free energy of the system with internal energy imposed as a constraint. Predictions from both the models have been compared against published data over a wide range of mixture compositions. Important differences in the regions close to flammability limits and for stoichiometric mixtures have been identified and explained. The equilibrium model has been validated for varied temperatures and pressures representative of initial conditions that may be present in the containment during accidents. Special emphasis has been given to the understanding of the role of dissociation and its effect on equilibrium pressure, temperature and species concentrations.
Kurzfassung
Während postulierter Störfallabfolgen in Kernreaktoren könnte Wasserstoff aus dem Kern freigesetzt werden und ein brennbares Gemisch im umgebenden Containment bilden. Die Entzündung solcher Gemische und die nachfolgende Druckerhöhung stellen eine unmittelbare Gefahr für den sicheren Betrieb des Reaktors dar. Methoden zur Bewertung der Nachentflammungseigenschaften sind wichtig zur Bestimmung der Sicherheitsbereiche bei der Systemauslegung für solche Szenarien. Dieser Beitrag stellt zwei thermo-chemische Modelle zur Bestimmung des Nachentflammungszustands vor. Das erste Modell basiert auf der internen Energiebilanz während das zweite Modell das Konzept von Elementpotentialen verwendet um die freie Energie des Systems zu minimieren. Die Vorhersagen beider Modelle wurden verglichen mit publizierten Daten über einen weiten Bereich von Gemisch-Zusammensetzungen. Wichtige Unterschiede in den Gebieten nahe der Zündgrenze und für stöchiometrische Gemische wurden festgestellt und erklärt. Das Gleichgewichtsmodell wurde validiert für verschiedene Temperaturen und Drucke, die für die Anfangsbedingungen im Containment während des Störfalls repräsentativ sind. Besonderer Wert wird auf das Verstehen der Rolle der Dissoziierung und ihres Einflusses auf Gleichgewichtsdruck, Temperatur und Spezieskonzentration gelegt.
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© 2016, Carl Hanser Verlag, München
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- Equilibrium based analytical model for estimation of pressure magnification during deflagration of hydrogen air mixtures
- Polynomial approach method to solve the neutron point kinetics equations with use of the analytic continuation
- The slab albedo problem for the triplet scattering kernel with modified FN method
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Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Technical Contributions/Fachbeiträge
- Use of molybdenum as a structural material of fuel elements for improving nuclear reactors safety
- Effect of ultra high temperature ceramics as fuel cladding materials on the nuclear reactor performance by SERPENT Monte Carlo code
- Spatial distribution of nanoparticles in PWR nanofluid coolant subjected to local nucleate boiling
- Impact of mesh points number on the accuracy of deterministic calculations of control rods worth for Tehran research reactor
- Dependence of neutron rate production with accelerator beam profile and energy range in an ADS-TRIGA RC1 reactor
- Effects of the wallpaper fuel design on the neutronic behavior of the HTR-10
- Loss of flow Accident (LOFA) analyses using LabView-based NRR simulator
- Basket criticality design of a dual purpose cask for VVER 1000 spent fuel assemblies
- Simulation of polycarbonate-CNT nanocomposite dosimeter based on electrical characteristics
- Thermoluminescence properties of micro and nano structure hydroxyapatite after gamma irradiation
- Equilibrium based analytical model for estimation of pressure magnification during deflagration of hydrogen air mixtures
- Polynomial approach method to solve the neutron point kinetics equations with use of the analytic continuation
- The slab albedo problem for the triplet scattering kernel with modified FN method
- Calculation of the fuel composition and the deterministic reloading pattern in the second cycle of the BUSHEHR VVER-1000 reactor using the weighting factor method
