Dryout heat flux experiments with deep heterogeneous particle bed

Ilona Lindholm (Corresponding Author), Stefan Holmström, Jaakko Miettinen, V. Lestinen, J. Hyvärinen, Pekka Pankakoski, H. Sjövall

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

A test facility has been constructed at Technical Research Centre of Finland (VTT) to simulate as accurately as possible the ex-vessel core particle bed in the conditions of Olkiluoto nuclear power plant. The STYX particle bed reproduces the anticipated depth of the bed and the size range of particles having irregular shape. The bed is immersed in water, creating top flooding conditions, and internally heated by an array of electrical resistance heating elements. Dryout tests have been successfully conducted at 0.1–0.7 MPa pressure for both uniformly mixed and stratified bed geometries. In all tests, including the stratified ones, the dry zone first formed near the bottom of the bed. The measured dryout heat fluxes increased with increasing pressure, from 232 kW/m2 at near atmospheric pressure to 451 kW/m2 at 0.7 MPa pressure. The data show some scatter even for the uniform bed. The tests with the stratified bed indicate a clear reduction of critical power due to the presence of a layer of small particles on top of the uniform bed. Comparison of data with various critical power (dryout heat flux) correlations for porous media shows that the most important parameter in the models is the effective particle diameter. Adiabatic debris bed flow resistance measurements were conducted to determine the most representative particle diameter. This diameter is close, but not equal, to the particle number-weighted average diameter of the bed material. With it, uniform bed data can be calculated to within an accuracy of 3–28% using Lipinski's 0-D model. In the stratified bed experiments, it appears that the top layer was partially fluidized, hence the measured critical power was significantly higher than calculated. Future experiments are being planned with denser top layer material to eliminate non-prototypic fluidization.
Original languageEnglish
Pages (from-to)2060-2074
Number of pages15
JournalNuclear Engineering and Design
Volume236
Issue number19-21
DOIs
Publication statusPublished - 2006
MoE publication typeA1 Journal article-refereed

Fingerprint

heat flux
Heat flux
beds
Electric heating elements
Acoustic impedance
experiment
Experiments
Fluidization
Test facilities
Debris
Nuclear power plants
Atmospheric pressure
Porous materials
Geometry
Water
fluidization
nuclear power plant
particle
atmospheric pressure
range size

Keywords

  • nuclear power plants
  • accidents
  • light water reactor coolant
  • cooling
  • LWR
  • light water reactors
  • core debris
  • simulation

Cite this

Lindholm, I., Holmström, S., Miettinen, J., Lestinen, V., Hyvärinen, J., Pankakoski, P., & Sjövall, H. (2006). Dryout heat flux experiments with deep heterogeneous particle bed. Nuclear Engineering and Design, 236(19-21), 2060-2074. https://doi.org/10.1016/j.nucengdes.2006.03.036
Lindholm, Ilona ; Holmström, Stefan ; Miettinen, Jaakko ; Lestinen, V. ; Hyvärinen, J. ; Pankakoski, Pekka ; Sjövall, H. / Dryout heat flux experiments with deep heterogeneous particle bed. In: Nuclear Engineering and Design. 2006 ; Vol. 236, No. 19-21. pp. 2060-2074.
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Lindholm, I, Holmström, S, Miettinen, J, Lestinen, V, Hyvärinen, J, Pankakoski, P & Sjövall, H 2006, 'Dryout heat flux experiments with deep heterogeneous particle bed', Nuclear Engineering and Design, vol. 236, no. 19-21, pp. 2060-2074. https://doi.org/10.1016/j.nucengdes.2006.03.036

Dryout heat flux experiments with deep heterogeneous particle bed. / Lindholm, Ilona (Corresponding Author); Holmström, Stefan; Miettinen, Jaakko; Lestinen, V.; Hyvärinen, J.; Pankakoski, Pekka; Sjövall, H.

In: Nuclear Engineering and Design, Vol. 236, No. 19-21, 2006, p. 2060-2074.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Dryout heat flux experiments with deep heterogeneous particle bed

AU - Lindholm, Ilona

AU - Holmström, Stefan

AU - Miettinen, Jaakko

AU - Lestinen, V.

AU - Hyvärinen, J.

AU - Pankakoski, Pekka

AU - Sjövall, H.

PY - 2006

Y1 - 2006

N2 - A test facility has been constructed at Technical Research Centre of Finland (VTT) to simulate as accurately as possible the ex-vessel core particle bed in the conditions of Olkiluoto nuclear power plant. The STYX particle bed reproduces the anticipated depth of the bed and the size range of particles having irregular shape. The bed is immersed in water, creating top flooding conditions, and internally heated by an array of electrical resistance heating elements. Dryout tests have been successfully conducted at 0.1–0.7 MPa pressure for both uniformly mixed and stratified bed geometries. In all tests, including the stratified ones, the dry zone first formed near the bottom of the bed. The measured dryout heat fluxes increased with increasing pressure, from 232 kW/m2 at near atmospheric pressure to 451 kW/m2 at 0.7 MPa pressure. The data show some scatter even for the uniform bed. The tests with the stratified bed indicate a clear reduction of critical power due to the presence of a layer of small particles on top of the uniform bed. Comparison of data with various critical power (dryout heat flux) correlations for porous media shows that the most important parameter in the models is the effective particle diameter. Adiabatic debris bed flow resistance measurements were conducted to determine the most representative particle diameter. This diameter is close, but not equal, to the particle number-weighted average diameter of the bed material. With it, uniform bed data can be calculated to within an accuracy of 3–28% using Lipinski's 0-D model. In the stratified bed experiments, it appears that the top layer was partially fluidized, hence the measured critical power was significantly higher than calculated. Future experiments are being planned with denser top layer material to eliminate non-prototypic fluidization.

AB - A test facility has been constructed at Technical Research Centre of Finland (VTT) to simulate as accurately as possible the ex-vessel core particle bed in the conditions of Olkiluoto nuclear power plant. The STYX particle bed reproduces the anticipated depth of the bed and the size range of particles having irregular shape. The bed is immersed in water, creating top flooding conditions, and internally heated by an array of electrical resistance heating elements. Dryout tests have been successfully conducted at 0.1–0.7 MPa pressure for both uniformly mixed and stratified bed geometries. In all tests, including the stratified ones, the dry zone first formed near the bottom of the bed. The measured dryout heat fluxes increased with increasing pressure, from 232 kW/m2 at near atmospheric pressure to 451 kW/m2 at 0.7 MPa pressure. The data show some scatter even for the uniform bed. The tests with the stratified bed indicate a clear reduction of critical power due to the presence of a layer of small particles on top of the uniform bed. Comparison of data with various critical power (dryout heat flux) correlations for porous media shows that the most important parameter in the models is the effective particle diameter. Adiabatic debris bed flow resistance measurements were conducted to determine the most representative particle diameter. This diameter is close, but not equal, to the particle number-weighted average diameter of the bed material. With it, uniform bed data can be calculated to within an accuracy of 3–28% using Lipinski's 0-D model. In the stratified bed experiments, it appears that the top layer was partially fluidized, hence the measured critical power was significantly higher than calculated. Future experiments are being planned with denser top layer material to eliminate non-prototypic fluidization.

KW - nuclear power plants

KW - accidents

KW - light water reactor coolant

KW - cooling

KW - LWR

KW - light water reactors

KW - core debris

KW - simulation

U2 - 10.1016/j.nucengdes.2006.03.036

DO - 10.1016/j.nucengdes.2006.03.036

M3 - Article

VL - 236

SP - 2060

EP - 2074

JO - Nuclear Engineering and Design

JF - Nuclear Engineering and Design

SN - 0029-5493

IS - 19-21

ER -

Lindholm I, Holmström S, Miettinen J, Lestinen V, Hyvärinen J, Pankakoski P et al. Dryout heat flux experiments with deep heterogeneous particle bed. Nuclear Engineering and Design. 2006;236(19-21):2060-2074. https://doi.org/10.1016/j.nucengdes.2006.03.036