Corium behavior and steam explosion risks: A review of experiments

Shen, Pei Kang; Zhou, Wei; Cassiaut-Louis, N.; Journeau, Christophe; Piluso, Pascal; Liao, Yehong

doi:10.1016/j.anucene.2018.07.029

Cited by 41 publications

(10 citation statements)

References 35 publications

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“…URING a postulated severe accident in either a Sodiumcooled Fast Reactor or a Light Water Reactor, molten core material (corium) may be discharged to the lower plenum and interact with the coolant. The progression of the subsequent fuel-coolant interaction (FCI) is likely to differ between corium-water [1][2][3] and corium-sodium interaction [4][5][6], however in each case the jet fragmentation will dictate the conditions for fuel-coolant contact and the mode of heat transfer, and may lead in some conditions to vapor explosions.…”

Section: Introductionmentioning

confidence: 99%

X-Ray Imaging Calibration for Fuel-Coolant Interaction Experimental Facilities

et al. 2021

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During a severe accident in either sodium-cooled or water-cooled nuclear reactors, jets of molten nuclear fuel may impinge on the coolant resulting in fuel-coolant interactions (FCI). Experimental programs are being conducted to study this phenomenology and to support the development of severe accident models. Due to the optical opacity of the test section walls, sodium coolant, and the apparent optical opacity of water in the presence of intense ebullition, high-speed X-ray imaging is the preferred technique for FCI visualization. The configuration of these X-ray imaging systems, whereby the test section is installed between a fan-beam X-ray source and a scintillator-image intensifier projecting an image in the visual spectrum onto a high-speed camera, entails certain imaging artefacts and uncertainties. The X-ray imaging configuration requires precise calibration to enable detailed quantitative characterization of the FCI. To this end, ‘phantom’ models have been fabricated using polyethylene, either steel or hafnia powder, and empty cavities to represent sodium, molten fuel and sodium vapor phases respectively. A checkerboard configuration of the phantom enables calibration and correction for lens distortion artefacts which magnify features towards the edge of the field of view. Polydisperse steel ball configurations enable precise determination of the lower limit of detection and the estimation of parallax errors which introduce uncertainty in an object’s silhouette dimensions. Calibration experiments at the MELT facility determined lower limits of detection in the order of 4 mm for steel spheres, and 1.7-3.75 mm for vapor films around a molten jet.

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Section: Introductionmentioning

confidence: 99%

X-Ray Imaging Calibration for Fuel-Coolant Interaction Experimental Facilities

et al. 2021

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“…To the best of the authors' knowledge, one of the last review papers on this subject was written by Berthoud [8] in 2000 and focused on the mechanical behavior of vapor explosions. Few review papers have been published since, such as Reference [9][10][11][12], but these discuss the available experimental technical bases, the modeling of vapor explosions on large scale or experiments specifically for the nuclear sector, while we intend to tackle the influence of heat transfer on the spontaneous triggering of vapor explosions on a smaller scale, specifically.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Considerations on the Spontaneous Triggering of Vapor Explosions—A Review

Simons

Bellemans

Crivits

et al. 2020

Metals

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Vapor explosions have been investigated both theoretically and experimentally for several decades, focusing either on the vapor film, or on mechanical aspects. Where the main interest for industry lies in the safety risks of such an event, fundamental research is focusing on all partial processes that occur during a vapor explosion. In this paper, vapor explosions are discussed from a heat transfer point of view. Generally accepted knowledge of heat transfer between hot surfaces and liquids is compared to early investigations regarding the origin of vapor explosions. Both steady state and transient models are discussed. The review of available literature suggests that vapor explosions trigger spontaneously by the collapse of the boiling film. Better understanding of the fundamental aspects of vapor explosions might give rise to future ideas on how to avoid them.

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“…Melt‐water explosion in the aluminum casting industry is one of potential hazards to personnel and facility 1,2 . Such explosions named fuel‐coolant interactions (FCIs) also could occur in other industrial applications, for example, the accidental spills of liquefied natural gas over water, 3 the direct contact of molten salt with water in paper‐pulp process, 4 even in the core meltdown accident of nuclear reactor 5 . These hazardous events involve the explosive boiling of volatile liquid in an extremely brief period, accompanied by the strong shock wave and splash of hot materials in general.…”

Section: Introductionmentioning

confidence: 99%

“…Considering severe accident scenarios to overall risk in light‐water nuclear system, steam explosions have been widely studied from the small to intermediate scale experiments using stimulant material (tin, steel, corium, gallium droplet, etc), for the understanding of the essential mechanism of premixing, triggering, propagating, and explosion stages in FCI. While the large‐scale experiments with prototypic melt (KROTOS, TROI, FARO, UKAEA MFTF, and MIXA), can provide the agglomeration effect of scale (mass) and constraint (geometry) on the consequence 5 . However, the obtained data are not enough for model and code verification so far.…”

Section: Introductionmentioning

confidence: 99%

“…While the large-scale experiments with prototypic melt (KROTOS, TROI, FARO, UKAEA MFTF, and MIXA), can provide the agglomeration effect of scale (mass) and constraint (geometry) on the consequence. 5 However, the obtained data are not enough for model and code verification so far. Seeing that large-scale experiments are insufficient for high cost and safety reasons, a selftriggering explosion setup for large-scale test was designed in this article, and the first results related to the explosion response (temperature and pressure), relative mass of melt and water, surface roughness, and metal oxide were presented.…”

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confidence: 99%

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Study on large‐scale steam explosion of molten aluminum and water

Shen

Chen

Zhongjie

et al. 2020

Process Safety Progress

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Explosive interaction can be originated from an inadvertent contract of molten metal and water, and most explosive accidents to date have been reported in the aluminum industry. In most cases, this incident is not a major problem to production, but do occur at some plants. Most previous work at small-scale experiments by bringing melt droplets into a water pool, with external trigger and controlled condition. These results are difficult to extend to large-scale events for the effect of scale. A new selftriggering test setup to deal with~10 kg molten aluminum for interaction under open condition was designed in this article, and the explosion energetics were first measured quantitatively. Results show that the mild explosion often occurs at relatively high aluminum/water mass ratio. Conversely, an intense explosion is more likely with higher water content. The peak temperature of intense explosion is only 247 C, and the overpressure detected in the surroundings is about 0.113 MPa. It is suggested that the carbon steel with high surface wettability could promote a spontaneous explosion, and the merely addition of metal oxide has little effect on the initiation of explosion. In view of above, two possible explosion scenarios are assessed on the superheated limit theory.

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Corium behavior and steam explosion risks: A review of experiments

Cited by 41 publications

References 35 publications

X-Ray Imaging Calibration for Fuel-Coolant Interaction Experimental Facilities

X-Ray Imaging Calibration for Fuel-Coolant Interaction Experimental Facilities

Heat Transfer Considerations on the Spontaneous Triggering of Vapor Explosions—A Review

Study on large‐scale steam explosion of molten aluminum and water

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