Hydrodynamic sweepout thresholds in BWR Mark III reactor cavity interactions

Technical Report · Sun Apr 01 04:00:00 EST 1984

DOI:https://doi.org/10.2172/6758917· OSTI ID:6758917

Spencer, B W; Baronowsky, S P; Kilsdonk, D J

Simulant-material experiments and related analysis are described which investigated hydrodynamics aspects of ex-vessel interactions following postulated core meltdown with subsequent meltthrough of the vessel lower head and ejection of molten corium from the vessel into the containment region beneath the vessel. Objectives were to examine the possible sweepout of water and corium from the cavity by the steam/H/sub 2/ flow. The dispersal pathways in this containment design include a single manway and four CRD penetrations in the cylindrical pedestal wall connecting to the drywell with a combined cross-sectional area of approx. 10 m/sup 2/. These openings range from 3.4 to 6.3 m in elevation off the concrete floor of the cavity. The experiments were performed using a 1:34 scale mock-up of the RPV/pedestal region. The first tests were quasi-steady tests. Tests were also performed using molten Wood's metal (WM). Some tests were performed with water on the cavity floor, and one test was performed using steel shot. The test results indicated that threshold gas flowrates existed beyond which dispersal of water and/or corium from the cavity can be expected. The predominant dispersal flow regime observed in the experiments involved fluidization of the water or molten WM by the gas flowrate through the system and sweepout of the fluidized liquid droplets as the gas exited the cavity through the openings in the wall. The superficial gas velocity at the onset of water sweepout ranged from 0.87 to 1.04 m/s in the tests which agrees very closely to the calculated fluidization threshold of 0.96 m/s. Application of the fluidization model for prediction of sweepout for the full-size system suggests that sweepout of water and corium can occur if the breach size in the RPV lower head exceeds approx. 10 and 17 cm dia, respectively, for steam blowdown at a vessel initial pressure of 1000 psi.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6758917
• Report Number(s): ANL/LWR/SAF-84-1; ON: DE84013937
• 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
BLOWDOWN
BWR TYPE REACTORS
CONTAINMENT
CORIUM
ELEMENTS
FLOW RATE
HYDROGEN
HYDROGEN COMPOUNDS
MELTDOWN
MOCKUP
NONMETALS
OXYGEN COMPOUNDS
REACTOR ACCIDENTS
REACTORS
SIMULATION
STEAM
STRUCTURAL MODELS
WATER
WATER COOLED REACTORS
WATER MODERATED REACTORS