An experimental study of the coolability of debris beds with geometry variations

Eveliina Takasuo (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

14 Citations (Scopus)

Abstract

The coolability of porous debris beds consisting of a simulant of solidified corium was investigated in an experimental study. The focus was on the effects of the geometrical shape of the debris bed and multi-dimensional flooding on the dryout heat flux. Dryout heat flux (DHF) was measured for six variations of the debris bed geometry, one of which was a classical, top-flooded cylinder and five that had more complex geometries. The complex geometries included conical and heap-shaped beds which can be considered prototypic to reactor scenarios. It was found that the multi-dimensional flooding related to heap-like geometries increases the DHF compared to top flooding by 47-73%. It was emphasized that the debris bed height has to be taken into account when assessing the coolability of realistic geometries: The heap-like geometry increases the dryout heat flux by facilitating multi-dimensional infiltration of water into the bed, but it also decreases the dryout power by having a greater height. The measured DHF increase represents a limit for the debris bed height, because if the increase in bed height is greater than the DHF increase, the direct benefit from the multi-dimensional flooding is lost. In addition, post-dryout conditions and their significance in the overall coolability of multi-dimensionally flooded beds were discussed.
Original languageEnglish
Pages (from-to)251-261
JournalAnnals of Nuclear Energy
Volume92
DOIs
Publication statusPublished - 2016
MoE publication typeA1 Journal article-refereed

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Debris
Heat flux
Geometry
Infiltration
Water

Keywords

  • severe accident
  • corium
  • debris bed
  • coolability
  • dryout heat flux
  • experimental facility

Cite this

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title = "An experimental study of the coolability of debris beds with geometry variations",
abstract = "The coolability of porous debris beds consisting of a simulant of solidified corium was investigated in an experimental study. The focus was on the effects of the geometrical shape of the debris bed and multi-dimensional flooding on the dryout heat flux. Dryout heat flux (DHF) was measured for six variations of the debris bed geometry, one of which was a classical, top-flooded cylinder and five that had more complex geometries. The complex geometries included conical and heap-shaped beds which can be considered prototypic to reactor scenarios. It was found that the multi-dimensional flooding related to heap-like geometries increases the DHF compared to top flooding by 47-73{\%}. It was emphasized that the debris bed height has to be taken into account when assessing the coolability of realistic geometries: The heap-like geometry increases the dryout heat flux by facilitating multi-dimensional infiltration of water into the bed, but it also decreases the dryout power by having a greater height. The measured DHF increase represents a limit for the debris bed height, because if the increase in bed height is greater than the DHF increase, the direct benefit from the multi-dimensional flooding is lost. In addition, post-dryout conditions and their significance in the overall coolability of multi-dimensionally flooded beds were discussed.",
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An experimental study of the coolability of debris beds with geometry variations. / Takasuo, Eveliina (Corresponding Author).

In: Annals of Nuclear Energy, Vol. 92, 2016, p. 251-261.

Research output: Contribution to journalArticleScientificpeer-review

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AB - The coolability of porous debris beds consisting of a simulant of solidified corium was investigated in an experimental study. The focus was on the effects of the geometrical shape of the debris bed and multi-dimensional flooding on the dryout heat flux. Dryout heat flux (DHF) was measured for six variations of the debris bed geometry, one of which was a classical, top-flooded cylinder and five that had more complex geometries. The complex geometries included conical and heap-shaped beds which can be considered prototypic to reactor scenarios. It was found that the multi-dimensional flooding related to heap-like geometries increases the DHF compared to top flooding by 47-73%. It was emphasized that the debris bed height has to be taken into account when assessing the coolability of realistic geometries: The heap-like geometry increases the dryout heat flux by facilitating multi-dimensional infiltration of water into the bed, but it also decreases the dryout power by having a greater height. The measured DHF increase represents a limit for the debris bed height, because if the increase in bed height is greater than the DHF increase, the direct benefit from the multi-dimensional flooding is lost. In addition, post-dryout conditions and their significance in the overall coolability of multi-dimensionally flooded beds were discussed.

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