Analysis of molten fuel-concrete interactions and fission-product release from ex-vessel core debris
Based on recent experiments and accident analysis at Sandia National Laboratories (SNL), four conclusions relevant to severe accident source-term evaluation can be drawn. First, the melt composition at the time of reactor pressure vessel failure is an important, yet uncertain, input to CORCON and VANESA. This is especially true of initial metallic zirconium content; the greater the zirconium content, the higher the aerosol and fission product release. Second, in experiments at SNL, addition of water on top of steel melts interacting with concrete was found to have little effect on concrete ablation. Boiling heat transfer on the melt surface was in the film boiling regime, and a stable crust formed at the melt/water interface. Analysis of this behavior indicates that similar behavior may occur under reactor accident conditions. Third, aerosol release results for these same SNL experiments indicate significant water pool decontamination, with decontamination factors of 1.7 to 17. Such a large attenuation in the aerosol source can be explained only partially by water pool scrubbing. Aerosol filtration by a surface crust is apparently the additional decontamination mechanism operative in the experiments. It is now known whether such a crust will form on reactor-scale melts. Finally, the tellurium release model in VANESA has been validated by comparison to experiment. This result is significant because VANESA predicts that ex-vessel tellurium release continues for a long time, and that most of the tellurium initially in the melt is released. 9 refs., 7 figs., 1 tab.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5053735
- Report Number(s):
- SAND-85-1857C; CONF-8510173-1; ON: DE86001748
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
220900* -- Nuclear Reactor Technology-- Reactor Safety
ABLATION
ACCIDENTS
AEROSOLS
BUILDING MATERIALS
BUILDINGS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COLLOIDS
COMPUTERIZED SIMULATION
CONCRETES
CONTAINMENT
CONTAINMENT BUILDINGS
CORIUM
DISPERSIONS
ELEMENTS
ENERGY TRANSFER
FISSION PRODUCT RELEASE
HEAT TRANSFER
MATERIALS
MELTDOWN
MELTING POINTS
PHYSICAL PROPERTIES
POWER REACTORS
RADIOACTIVE AEROSOLS
REACTOR ACCIDENTS
REACTORS
SEMIMETALS
SIMULATION
SOLS
TELLURIUM
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE