Modeling of Water Ingression Mechanism for Corium Cooling with MELCOR

Tuomo Sevón (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

The water ingression mechanism can enhance the coolability of a pool of molten corium in containment during a severe accident. A water ingression model was added to the MELCOR code in 2015. The purpose of this work was to test the new model. It was found that the water ingression model performed satisfactorily in core-concrete-interaction experiments in which gas bubbles were released to the melt from decomposing concrete. The new model had little effect in the Small-Scale Water Ingression and Crust Strength (SSWICS) experiments that were done without gas bubbling through the melt. When applied to the Fukushima Daiichi Unit 1 accident, the water ingression model slowed down concrete ablation by 19% but did not quench the melt. Because the water ingression model was added to MELCOR so recently, the default treatment is still to use multipliers for the boiling heat transfer coefficient and thermal conductivity instead of the proper water ingression model. These default parameters significantly overestimated melt coolability in all the experiments that were calculated.
Original languageEnglish
Pages (from-to)171-179
Number of pages9
JournalNuclear Technology
Volume197
Issue number2
DOIs
Publication statusPublished - 1 Feb 2017
MoE publication typeA1 Journal article-refereed

Fingerprint

Cooling
cooling
water
Water
Concretes
accidents
Accidents
containment
Experiments
multipliers
Ablation
heat transfer coefficients
Gases
gases
boiling
Boiling liquids
Heat transfer coefficients
ablation
Molten materials
crusts

Keywords

  • MCCI
  • water ingression
  • MELCOR

Cite this

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title = "Modeling of Water Ingression Mechanism for Corium Cooling with MELCOR",
abstract = "The water ingression mechanism can enhance the coolability of a pool of molten corium in containment during a severe accident. A water ingression model was added to the MELCOR code in 2015. The purpose of this work was to test the new model. It was found that the water ingression model performed satisfactorily in core-concrete-interaction experiments in which gas bubbles were released to the melt from decomposing concrete. The new model had little effect in the Small-Scale Water Ingression and Crust Strength (SSWICS) experiments that were done without gas bubbling through the melt. When applied to the Fukushima Daiichi Unit 1 accident, the water ingression model slowed down concrete ablation by 19{\%} but did not quench the melt. Because the water ingression model was added to MELCOR so recently, the default treatment is still to use multipliers for the boiling heat transfer coefficient and thermal conductivity instead of the proper water ingression model. These default parameters significantly overestimated melt coolability in all the experiments that were calculated.",
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Modeling of Water Ingression Mechanism for Corium Cooling with MELCOR. / Sevón, Tuomo (Corresponding Author).

In: Nuclear Technology, Vol. 197, No. 2, 01.02.2017, p. 171-179.

Research output: Contribution to journalArticleScientificpeer-review

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AB - The water ingression mechanism can enhance the coolability of a pool of molten corium in containment during a severe accident. A water ingression model was added to the MELCOR code in 2015. The purpose of this work was to test the new model. It was found that the water ingression model performed satisfactorily in core-concrete-interaction experiments in which gas bubbles were released to the melt from decomposing concrete. The new model had little effect in the Small-Scale Water Ingression and Crust Strength (SSWICS) experiments that were done without gas bubbling through the melt. When applied to the Fukushima Daiichi Unit 1 accident, the water ingression model slowed down concrete ablation by 19% but did not quench the melt. Because the water ingression model was added to MELCOR so recently, the default treatment is still to use multipliers for the boiling heat transfer coefficient and thermal conductivity instead of the proper water ingression model. These default parameters significantly overestimated melt coolability in all the experiments that were calculated.

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