Verification and validation of numerical models of the transport of insulation debris

G.M. Cartland Glover, A. Kratzsch, E. Krepper, S. Renger, A. Seeliger, F. Zacharias, S. Alt, W. Kästner, H. Kryk, F. P. Weiss

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

Abstract

Damage to insulation materials located near to a primary circuit coolant leak may compromise the operation of the emergency core cooling system (ECCS). Insulation material in the form of mineral wool fiber agglomerates (MWFA) maybe transported to the containment sump strainers, where they may block or penetrate the strainers. Though the impact of MWFA on the pressure drop across the strainers is minimal, corrosion products formed over time may also accumulate in the fiber cakes on the strainers, which can lead to a significant increase in the strainer pressure drop and result in cavitation in the ECCS.
An experimental and theoretical study performed by the Helmholtz-Zentrum Dresden-Rossendorf and the Hochschule Zittau/Görlitz is investigating the phenomena that maybe observed in the containment vessel during a primary circuit coolant leak. The study entails the generation of fiber agglomerates, the determination of their transport properties in single and multi-effect experiments and the long-term effect that corrosion and erosion of the containment internals by the coolant has on the strainer pressure drop.
The focus of this paper is on the verification and validation of numerical models that can predict the transport of MWFA. A number of pseudo-continuous dispersed phases of spherical wetted agglomerates represent the MWFA. The size, density, the relative viscosity of the fluid-fiber agglomerate mixture and the turbulent dispersion all affect how the fiber agglomerates are transported. In the cases described here, the size is kept constant while the density is modified. This definition affects both the terminal velocity and volume fraction of the dispersed phases. Note that the relative viscosity is only significant at high concentrations.
Three single effect experiments were used to provide validation data on the transport of the fiber agglomerates under conditions of sedimentation in quiescent fluid, sedimentation in a horizontal flow and suspension in a horizontal flow. The experiments were performed in a rectangular column for the quiescent fluid and a racetrack type channel that provided a near uniform horizontal flow. The numerical models of sedimentation in the column and the racetrack channel found that the sedimentation characteristics are consistent with the experiments. For channel suspension, the heavier fibers tend to accumulate at the channel base even at high velocities, while lighter phases are more likely to be transported around the channel.
Original languageEnglish
Title of host publicationProceedings of the 14th International Topical Meeting on Nuclear Reactor Thermalhydraulics (NURETH-14)
PublisherASME
Publication statusPublished - 25 Sep 2011
Event14th International Topical Meeting on Nuclear Reactor Thermalhydraulics - Toronto, Canada
Duration: 25 Sep 201129 Sep 2011

Other

Other14th International Topical Meeting on Nuclear Reactor Thermalhydraulics
CountryCanada
CityToronto
Period25/09/1129/09/11

Bibliographical note

CD-ROM
Subsequently submitted to a Special Issue of the Journal of Computational Multiphase Flows

Keywords

  • mineral wool fiber agglomerates
  • loss of coolant accidents
  • containment sump
  • computational fluid dynamics
  • multiphase flow

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  • Research Output

    Verification and validation of numerical models of the transport of insulation debris

    Cartland Glover, G. M., Kratzsch, A., Krepper, E., Renger, S., Seeliger, A., Zacharias, F., Alt, S., Kästner, W., Kryk, H. & Weiss, F-P., Sep 2012, In : The Journal of Computational Multiphase Flows. 4, 3, p. 255-270 16 p.

    Research output: Contribution to journalArticle

    Open Access
  • Cite this

    Cartland Glover, G. M., Kratzsch, A., Krepper, E., Renger, S., Seeliger, A., Zacharias, F., Alt, S., Kästner, W., Kryk, H., & Weiss, F. P. (2011). Verification and validation of numerical models of the transport of insulation debris. In Proceedings of the 14th International Topical Meeting on Nuclear Reactor Thermalhydraulics (NURETH-14) ASME. http://nureth14.org/index.html