The effect of functional spacers on the liquid film thickness and dryout in a BWR fuel bundle model

Christian Bolesch, Lukas Robers, Robert Zboray, Horst Michael Prasser

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    For the BWRs, the dryout margin is one of the core design limitation factors. Today’s industry standard is to use a large margin to dryout and functional spacer grids with vanes to enhance the heat transfer and to reduce the fraction of entrained droplets. Difficulties for precise measurements under reactor conditions lead to a lack of knowledge on the exact effects of the spacers on the flow and suggest the use of scaled experiments. For this experiment, the goal is to provide high-resolution data for CFD code validation as well as visualizing the effects of functional spacers and the liquid film and potentially the dryout front. The Dryout Tomography Experiment (DoToX) facility at ETH Zürich is a closed loop experiment for two-phase flow investigations in a fuel bundle model using a modelling fluid. Key aspects are a single undisturbed subchannel and the surrounding four heating rods containing a liquid heating system. This setup allows for a steady state dryout without endangering the structural integrity of the facility and for the 3D reconstruction of the time averaged void distribution within the flow channel by means of an X-Ray and cold neutron Computer Tomography (CT). In this study we pay special attention to the annular flow in the upper half of the sub channel. We investigate the first results delivered by the facility. Prototypical spacer designs available in the open literature were used. We present the Liquid Film Thickness (LFT) distributions on the walls of the heating rods. Improvements towards the dryout performance as well as drawbacks of the specified spacer design are highlighted.

    Original languageEnglish (US)
    Title of host publicationThermal-Hydraulics and Safety Analyses
    PublisherAmerican Society of Mechanical Engineers (ASME)
    Volume6A
    ISBN (Print)9784888982566
    DOIs
    StatePublished - Jan 1 2018
    Event2018 26th International Conference on Nuclear Engineering, ICONE 2018 - London, United Kingdom
    Duration: Jul 22 2018Jul 26 2018

    Other

    Other2018 26th International Conference on Nuclear Engineering, ICONE 2018
    CountryUnited Kingdom
    CityLondon
    Period7/22/187/26/18

    Fingerprint

    Liquid films
    Film thickness
    Heating
    Tomography
    Experiments
    Structural integrity
    Channel flow
    Two phase flow
    Neutrons
    Computational fluid dynamics
    Heat transfer
    X rays
    Fluids
    Liquids
    Industry

    All Science Journal Classification (ASJC) codes

    • Nuclear Energy and Engineering

    Cite this

    Bolesch, C., Robers, L., Zboray, R., & Prasser, H. M. (2018). The effect of functional spacers on the liquid film thickness and dryout in a BWR fuel bundle model. In Thermal-Hydraulics and Safety Analyses (Vol. 6A). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/ICONE26-81602
    Bolesch, Christian ; Robers, Lukas ; Zboray, Robert ; Prasser, Horst Michael. / The effect of functional spacers on the liquid film thickness and dryout in a BWR fuel bundle model. Thermal-Hydraulics and Safety Analyses. Vol. 6A American Society of Mechanical Engineers (ASME), 2018.
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    abstract = "For the BWRs, the dryout margin is one of the core design limitation factors. Today’s industry standard is to use a large margin to dryout and functional spacer grids with vanes to enhance the heat transfer and to reduce the fraction of entrained droplets. Difficulties for precise measurements under reactor conditions lead to a lack of knowledge on the exact effects of the spacers on the flow and suggest the use of scaled experiments. For this experiment, the goal is to provide high-resolution data for CFD code validation as well as visualizing the effects of functional spacers and the liquid film and potentially the dryout front. The Dryout Tomography Experiment (DoToX) facility at ETH Z{\"u}rich is a closed loop experiment for two-phase flow investigations in a fuel bundle model using a modelling fluid. Key aspects are a single undisturbed subchannel and the surrounding four heating rods containing a liquid heating system. This setup allows for a steady state dryout without endangering the structural integrity of the facility and for the 3D reconstruction of the time averaged void distribution within the flow channel by means of an X-Ray and cold neutron Computer Tomography (CT). In this study we pay special attention to the annular flow in the upper half of the sub channel. We investigate the first results delivered by the facility. Prototypical spacer designs available in the open literature were used. We present the Liquid Film Thickness (LFT) distributions on the walls of the heating rods. Improvements towards the dryout performance as well as drawbacks of the specified spacer design are highlighted.",
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    Bolesch, C, Robers, L, Zboray, R & Prasser, HM 2018, The effect of functional spacers on the liquid film thickness and dryout in a BWR fuel bundle model. in Thermal-Hydraulics and Safety Analyses. vol. 6A, American Society of Mechanical Engineers (ASME), 2018 26th International Conference on Nuclear Engineering, ICONE 2018, London, United Kingdom, 7/22/18. https://doi.org/10.1115/ICONE26-81602

    The effect of functional spacers on the liquid film thickness and dryout in a BWR fuel bundle model. / Bolesch, Christian; Robers, Lukas; Zboray, Robert; Prasser, Horst Michael.

    Thermal-Hydraulics and Safety Analyses. Vol. 6A American Society of Mechanical Engineers (ASME), 2018.

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

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    Bolesch C, Robers L, Zboray R, Prasser HM. The effect of functional spacers on the liquid film thickness and dryout in a BWR fuel bundle model. In Thermal-Hydraulics and Safety Analyses. Vol. 6A. American Society of Mechanical Engineers (ASME). 2018 https://doi.org/10.1115/ICONE26-81602