Numerical study on thermal hydraulic phenomena in a hemispherical gap under core meltdown accident

Akihiro Uchibori, Kenji Fukuda, Koji Morita, Tatsuya Matsumoto

Research output: Contribution to journalArticle

Abstract

Numerical analytical method for thermal hydraulic phenomena in a hemispherical narrow gap flow passage was developed to evaluate heat removal capability with gap formation between the reactor pressure vessel (RPV) and the molten core debris. The problem of gap cooling mechanism was modeled as vapor-liquid two-phase flow in the gap with two-dimensional spherical coordinates system. The analytical model is based on a modified drift flux model for multi-dimensional two-phase flow analyses. Numerical results showed that liquid-phase intrusion into the gap in the counter direction of gas-phase upward flow keeps down a rise of void fraction as gap cooling effect. The applied heat flux, which leads to expansion of high void fraction region with the state of partial counter-current flow limitation (CCFL), was regarded as predictive value for partial critical heat flux (CHF). The predicted partial CHF in the analyses were compared with other measurements and correlations obtained from some CHF experimental studies.

Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalAmerican Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
Volume424
Publication statusPublished - Dec 1 2000

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Core meltdown
hydraulic phenomena
heat flux
accident
Heat flux
Accidents
Hydraulics
Void fraction
two phase flow
Two phase flow
void
Cooling
cooling
liquid
countercurrent
Liquids
Pressure vessels
Debris
Molten materials
Analytical models

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

Cite this

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AU - Uchibori, Akihiro

AU - Fukuda, Kenji

AU - Morita, Koji

AU - Matsumoto, Tatsuya

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AB - Numerical analytical method for thermal hydraulic phenomena in a hemispherical narrow gap flow passage was developed to evaluate heat removal capability with gap formation between the reactor pressure vessel (RPV) and the molten core debris. The problem of gap cooling mechanism was modeled as vapor-liquid two-phase flow in the gap with two-dimensional spherical coordinates system. The analytical model is based on a modified drift flux model for multi-dimensional two-phase flow analyses. Numerical results showed that liquid-phase intrusion into the gap in the counter direction of gas-phase upward flow keeps down a rise of void fraction as gap cooling effect. The applied heat flux, which leads to expansion of high void fraction region with the state of partial counter-current flow limitation (CCFL), was regarded as predictive value for partial critical heat flux (CHF). The predicted partial CHF in the analyses were compared with other measurements and correlations obtained from some CHF experimental studies.

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