Natural convection model of molten pool penetration into a melting miscible substrate

Conference · Fri Jan 01 04:00:00 EST 1993 · Transactions of the American Nuclear Society; (United States)

OSTI ID:6844282

Epstein, M ^[1]

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1. Fauske Associates Inc., Burr Ridge, IL (United States)

Studies of postulated severe accidents in nuclear reactors have involved consideration of the extent of core-debris-melt penetration into the lighter and miscible concrete substrate below the reactor vessel. It is suggested in this paper that the melting of concrete by an overlying pool of oxidic core material/concrete mixture is partially driven by classical liquid-turbulent natural convection, with plumes of molten concrete providing the required strong mixing conditions. Experiments have shown that the melting of a solid by a heavier overlying hot pool miscible with the solid material in the absence of gas bubbling is a boundary-layer phenomenon involving the steady generation of narrow columns or streamers of melt material from a stable melt layer that exists between the melting solid and an overlying pool. The streamers originate at discrete sites at the melt layer/pool interface and continuously inject melt material into the overlying pool. It is reasonable to assume that streamers of molten concrete are present near the bottom of the overlying oxidic core material pool. It can be demonstrated with the analysis described in the next paragraph that the streamers rather than gas bubbles are chiefly responsible for concrete slag removal and mixing with the oxidic pool and are capable of producing a level of thermal convection within the oxidic pool that is comparable to that produced by gas bubbling. This important phenomenon has not been considered in the available models of molten-core debris/concrete heat transfer.

• OSTI ID: 6844282
• Report Number(s): CONF-931160--
• Conference Information: Journal Name: Transactions of the American Nuclear Society; (United States) Journal Volume: 69
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
BUILDING MATERIALS
CONCRETES
CONVECTION
CORIUM
ENERGY TRANSFER
HEAT TRANSFER
MASS TRANSFER
MATERIALS
MATHEMATICAL MODELS
MELTING
NATURAL CONVECTION
PHASE TRANSFORMATIONS
POWER REACTORS
REACTOR ACCIDENTS
REACTOR CORE DISRUPTION
REACTORS