Experimental study and analytical methods for particle bed dryout with heterogeneous particles and pressure variation

Jaakko Miettinen, Stefan Holmström, Risto Sairanen, Ilona Lindholm

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    3 Citations (Scopus)


    The interest to study the dryout heat flux in particle beds is related to interest of quantify the debris coolability margins during a hypothetical severe reactor accident. When the molten core has relocated to the containment floor, one accident management concept is based on the cooling of the corium by the water injection on top. Earlier experimental and analytical work has concentrated on homogeneous particle beds at atmospheric pressures. For plant safety assessment in Finland, there is a need to consider heterogeneous particle mixtures, layered particle bed setups and varied pressures. A facility has been constructed at VTT to measure dryout heat flux in a heterogeneous particle bed. The bed dimensions are 0.3 m in diameter and 0.6 m in height, with a mixture of 0.1 to 10 mm particles. The facility has a pressure range from atmospheric to 6 bar (overpressure). The bed is heated by spirals of a resistance band. The preliminary experiments have been carried out, but a more systematic set of data is expected to be available in the spring 2002. To support the experiments analytical models have been developed for qualification of the experimental results. The first comparison is done against various critical heat flux correlations developed in 1980’ies and 1990’ies for homogeneous bed conditions. The second comparison is done against 1-D and 0-D models developed by Lipinski. The most detailed analysis of the transient process conditions and dryout predictions are done by using the two-dimensional, drift-flux based thermohydraulic solution for the particle bed immersed into the water. The code is called PILEXP. Already the first validation results against the preliminary tests indicate that the transient process conditions and the mechanisms related to the dryout can be best explained and understood by using a multidimensional, transient code, where all details of the process control can be modeled as well. The heterogeneous bed and stratified bed can not be well considered by single critical heat flux correlations.
    Original languageEnglish
    Title of host publication10th International Conference on Nuclear Engineering
    Subtitle of host publicationSafety, Reliability and Plant Evaluations
    PublisherAmerican Society of Mechanical Engineers (ASME)
    ISBN (Electronic)978-0-7918-3596-8
    ISBN (Print)978-0-7918-3589-0
    Publication statusPublished - 2002
    MoE publication typeA4 Article in a conference publication
    Event10th International Conference on Nuclear Engineering, ICONE 10 - Arlington, United States
    Duration: 14 Apr 200218 Apr 2002


    Conference10th International Conference on Nuclear Engineering, ICONE 10
    Country/TerritoryUnited States


    • particle bed
    • dryout heat flux
    • severe accidents


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