Xenon instability study of large core Monte Carlo calculations
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E. V. Bogdanova
Abstract
One of the goals of neutronic calculations of large cores may be self-consistent distribution of equilibrium xenon through the reactor core. In deterministic calculations such self consistency is relatively simply achieved with the help of additional outer iterations by xenon, which can increase several times solution run time. But in stochastic calculation of large cores such increase is utterly undesirable, since even without these outer iterations it demands modeling of billion of histories, which in case of complicated large core may take about a day of 100 processors work. In addition the unavoidable statistical uncertainty here plays role of transient process, which excites xenon oscillations. In this work the rise of such oscillations and the way of their overcoming with the help of hybrid stochastic/deterministic calculation is studied. It is proposed to make at first single static Monte Carlo calculation of given core and to receive multi-group mesh cell characteristics for future use in operative code. This one will evaluate xenon distribution through the core, which will be equilibrium for deterministic solution and substantially close to equilibrium Monte Carlo solution, paid with enormous computing cost.
Kurzfassung
Ein Ziel der Berechnung der Neutronenkinetik von großen Kernen ist die Berechnung einer in sich stimmigen Gleichgewichtsverteilung des Xenons im Reaktorkern. Bei deterministischen Rechnungen wird dies mit zusätzlichen Iterationen für das Xenon erreicht, die aber die Gesamtrechenzeit entscheidend vergrößern. Bei stochastischen Rechnungen soll dieser Anstieg der Rechenzeit unbedingt vermieden werden, da Rechnungen großer Kerne schon ohne diese Zusatziterationen bis zu 100 Tagen Rechenzeit benötigen können. Zusätzlich treten bei der Berechnung von Transienten nicht vermeidbare statistische Unsicherheiten auf, die die Größenordnung der eigentlichen Xenonoszillationen übersteigen. In diesem Beitrag werden diese Oszillationen untersucht und es wird eine Methode entwickelt, diese durch eine kombinierte stochastisch/deterministische Analyse zu überwinden. Es wird vorgeschlagen zuerst einfache stationäre Monte-Carlo-Berechnungen des zu untersuchenden Kerns durchzuführen und damit Mehrgruppen-Charakteristika der Gitterzellen für die weitere Nutzung zu erzeugen. Damit können dann die Xenonverteilungen im Kern bestimmt werden, die zum einen den deterministisch berechneten Gleichgewichtslösungen entsprechen und zum anderen den Monte-Carlo-Gleichgewichtslösungen am nächsten kommen. Dieses Vorgehen spart enorme Rechenzeiten.
References
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© 2016, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Editorial
- Research on the reactor physics and reactor safety of VVER reactors – AER Symposium 2015
- Technical Contributions/Fachbeiträge
- Monte-Carlo code calculation of 3D reactor core model with usage of burnt fuel isotopic compositions, obtained by engineering codes
- Xenon instability study of large core Monte Carlo calculations
- Error detection in core loading in the condition of asymmetrical distribution of power
- New models in VERONA 7.0 system
- Methodology for determining of the weighted mean coolant temperature in the primary circuit hot legs of WWER-1000 reactor plants
- Verification of three-dimensional neutron kinetics model of TRAP-KS code regarding reactivity variations
- Aspects of using a best-estimate approach for VVER safety analysis in reactivity initiated accidents
- Qualification of coupled 3D neutron kinetic/thermal hydraulic code systems by the calculation of a VVER-440 benchmark – re-connection of an isolated loop
- Uncertainties of the KIKO3D-ATHLET calculations using the Kalinin-3 benchmark (Phase II) data
- Coupled code analysis of uncertainty and sensitivity of Kalinin-3 benchmark
- Efficient introduction of natural uranium and thorium into nuclear energy system
- Economical aspects of multiple plutonium and uranium recycling in VVER reactors
- Neutronic analysis of absorbing materials for the control rod system in reactor ALLEGRO
- Uncertainty analysis and flow measurements in an experimental mock-up of a molten salt reactor concept
Articles in the same Issue
- Contents/Inhalt
- Contents
- Summaries/Kurzfassungen
- Summaries
- Editorial
- Research on the reactor physics and reactor safety of VVER reactors – AER Symposium 2015
- Technical Contributions/Fachbeiträge
- Monte-Carlo code calculation of 3D reactor core model with usage of burnt fuel isotopic compositions, obtained by engineering codes
- Xenon instability study of large core Monte Carlo calculations
- Error detection in core loading in the condition of asymmetrical distribution of power
- New models in VERONA 7.0 system
- Methodology for determining of the weighted mean coolant temperature in the primary circuit hot legs of WWER-1000 reactor plants
- Verification of three-dimensional neutron kinetics model of TRAP-KS code regarding reactivity variations
- Aspects of using a best-estimate approach for VVER safety analysis in reactivity initiated accidents
- Qualification of coupled 3D neutron kinetic/thermal hydraulic code systems by the calculation of a VVER-440 benchmark – re-connection of an isolated loop
- Uncertainties of the KIKO3D-ATHLET calculations using the Kalinin-3 benchmark (Phase II) data
- Coupled code analysis of uncertainty and sensitivity of Kalinin-3 benchmark
- Efficient introduction of natural uranium and thorium into nuclear energy system
- Economical aspects of multiple plutonium and uranium recycling in VVER reactors
- Neutronic analysis of absorbing materials for the control rod system in reactor ALLEGRO
- Uncertainty analysis and flow measurements in an experimental mock-up of a molten salt reactor concept
