Core structure heat-up and material relocation in a BWR short-term station blackout accident
This paper presents an analytical and numerical analysis which evaluates the core-structure heat-up and subsequent relocation of molten core materials during a NWR short-term station blackout accident with ADS. A simplified one-dimensional approach coupled with bounding arguments is first presented to establish an estimate of the temperature differences within a BWR assembly at the point when structural material first begins to melt. This analysis leads to the conclusions that the control blade will be the first structure to melt and that at this point in time, overall temperature differences across the canister-blade region will not be more than 200 K. Next, a three-dimensional heat-transfer model of the canister-blade region within the core is presented that uses a diffusion approximation for the radiation heat transfer. This is compared to the one-dimensional analysis to establish its compatibility. Finally, the extension of the three-dimensional model to include melt relocation using a porous media type approximation is described. The results of this analysis suggest that under these conditions significant amounts of material will relocate to the core plate region and refreeze, potentially forming a significant blockage. The results also indicate that a large amount of lateral spreading of the melted blade and canister material into the fuel rod regions will occur during the melt progression process. 22 refs., 18 figs., 1 tab.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- Sponsoring Organization:
- NRC
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6499322
- Report Number(s):
- SAND-90-1525C; CONF-901101--37; ON: DE91001226
- Country of Publication:
- United States
- Language:
- English
Similar Records
Final results of the XR2-1 BWR metallic melt relocation experiment
BWR core melt progression phenomena: Experimental analyses
Related Subjects
210100 -- Power Reactors
Nonbreeding
Light-Water Moderated
Boiling Water Cooled
22 GENERAL STUDIES OF NUCLEAR REACTORS
220900* -- Nuclear Reactor Technology-- Reactor Safety
ACCIDENTS
AFTER-HEAT REMOVAL
BLACKOUTS
BWR TYPE REACTORS
CORIUM
ENERGY TRANSFER
FLUID MECHANICS
FUEL ELEMENTS
HEAT TRANSFER
HYDRAULICS
MATHEMATICAL MODELS
MATHEMATICS
MECHANICS
MELTDOWN
NUMERICAL ANALYSIS
ONE-DIMENSIONAL CALCULATIONS
REACTOR ACCIDENTS
REACTOR COMPONENTS
REACTOR CORES
REACTOR SAFETY
REACTORS
REMOVAL
SAFETY
THREE-DIMENSIONAL CALCULATIONS
WATER COOLED REACTORS
WATER MODERATED REACTORS