Effects of lateral separation of oxidic and metallic core debris on the BWR (Boiling Water Reactor) MK I containment drywell floor

Technical Report · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6658826

Hyman, C R; Weber, C F

In evaluating core debris/concrete interactions for a BWR MK I containment design, it has been common practice to assume that at reactor vessel breach, the core debris is homogeneous and of low viscosity so that it is uniformly distributed radially on the drywell floor. In a recent study performed by the NRC-sponsored Severe Accident Sequence Analysis (SASA) program at Oak Ridge National Laboratory, calculations indicate that at reactor vessel bottom head failure, the debris temperature is such that the metallic components (Zr, Fe, Ni, Cr) are completely molten while the oxidic components (UO/sub 2/, ZrO/sub 2/, FeO) are completely frozen. Thus, the frozen oxides are expected to remain within the reactor pedestal while the molten metallic species radially separate from the frozen oxidic species, flow through the opening in the reactor pedestal, and spread over the annular region of the drywell floor between the pedestal and the containment shell. This report assesses the impact on calculated debris gas release and the production and release of fission product-laden aerosols for two different cases of debris distribution: uniform distribution, and the laterally separated case of 95% oxides-5% metals inside the pedestal and 5% oxides-95% metals outside the pedestal. The computer codes used in this assessment are CORCON-MOD 2, MARCON 2.1B and VANESA.

• Research Organization: Oak Ridge National Lab., TN (USA); Nuclear Regulatory Commission, Washington, DC (USA). Office of Nuclear Regulatory Research
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6658826
• Report Number(s): NUREG/CR-4610; ORNL/TM-10057; ON: TI87005234
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
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
BUILDING MATERIALS
BWR TYPE REACTORS
COMPUTER CALCULATIONS
CONCRETES
CONTAINERS
CONTAINMENT
CONTAINMENT SYSTEMS
CORIUM
ELEMENTS
ENERGY TRANSFER
ENGINEERED SAFETY SYSTEMS
FLUID MECHANICS
HEAT TRANSFER
HYDRAULICS
LAYERS
MATERIALS
MECHANICS
MELTDOWN
METALS
MINERALS
OXIDE MINERALS
RADIOACTIVE EFFLUENTS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
REACTOR ACCIDENTS
REACTOR COMPONENTS
REACTOR CORE DISRUPTION
REACTOR CORES
REACTOR MATERIALS
REACTOR SAFETY
REACTOR VESSELS
REACTORS
REMOVAL
SAFETY
WASTES
WATER COOLED REACTORS
WATER MODERATED REACTORS