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Title: SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head

Abstract

A model is described for the movement of melted metallic material through a ceramic porous debris bed. The model is designed for the analysis of severe accidents in LWRs, wherein melted core plate material may slump onto the top of a porous bed of relocated core material supported by the lower head. The permeation of the melted core plate material into the porous debris bed influences the heatup of the debris bed and the heatup of the lower head supporting the debris. A model for mass transport of melted metallic material is applied that includes terms for viscosity and turbulence but neglects inertial and capillary terms because of their small value relative to gravity and viscous terms in the momentum equation. The relative permeability and passability of the porous debris are calculated as functions of debris porosity, particle size, and effective saturation. An iterative numerical solution is used to solve the set of nonlinear equations for mass transport. The effective thermal conductivity of the debris is calculated as a function of porosity, particle size, and saturation. The model integrates the equations for mass transport with a model for the two-dimensional conduction of heat through porous debris. The integrated model hasmore » been implemented into the SCDAP/RELAP5 code for the analysis of the integrity of LWR lower heads during severe accidents. The results of the model indicate that melted core plate material may permeate to near the bottom of a 1m deep hot porous debris bed supported by the lower head. The presence of the relocated core plate material was calculated to cause a 12% increase in the heat flux on the external surface of the lower head.« less

Authors:
;
Publication Date:
Research Org.:
Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
758108
Report Number(s):
INEEL/CON-99-01324
TRN: US0003761
DOE Contract Number:  
AC07-99ID13727
Resource Type:
Conference
Resource Relation:
Conference: 8th International Conference on Nuclear Engineering (ICONE 8), Baltimore, MD (US), 04/02/2000--04/07/2000; Other Information: PBD: 2 Apr 2000
Country of Publication:
United States
Language:
English
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; WATER COOLED REACTORS; POROUS MATERIALS; REACTOR ACCIDENTS; MASS TRANSFER; S CODES; R CODES; CORIUM; HEAT TRANSFER; MATHEMATICAL MODELS; MELTED METALLIC MATERIAL; CERAMIC POROUS DEBRIS BED; SEVERE ACCIDENTS; LOWER HEAD; MASS TRANSPORT; VISCOSITY; TURBULENCE; MOMENTUM EQUATION; NUMERICAL SOLUTION; THERMAL CONDUCTIVITY; SCDAP/RELAP5; HEAT FLUX

Citation Formats

L. J. Siefken, and E. A. Harvego. SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head. United States: N. p., 2000. Web.
L. J. Siefken, & E. A. Harvego. SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head. United States.
L. J. Siefken, and E. A. Harvego. Sun . "SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head". United States. https://www.osti.gov/servlets/purl/758108.
@article{osti_758108,
title = {SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head},
author = {L. J. Siefken and E. A. Harvego},
abstractNote = {A model is described for the movement of melted metallic material through a ceramic porous debris bed. The model is designed for the analysis of severe accidents in LWRs, wherein melted core plate material may slump onto the top of a porous bed of relocated core material supported by the lower head. The permeation of the melted core plate material into the porous debris bed influences the heatup of the debris bed and the heatup of the lower head supporting the debris. A model for mass transport of melted metallic material is applied that includes terms for viscosity and turbulence but neglects inertial and capillary terms because of their small value relative to gravity and viscous terms in the momentum equation. The relative permeability and passability of the porous debris are calculated as functions of debris porosity, particle size, and effective saturation. An iterative numerical solution is used to solve the set of nonlinear equations for mass transport. The effective thermal conductivity of the debris is calculated as a function of porosity, particle size, and saturation. The model integrates the equations for mass transport with a model for the two-dimensional conduction of heat through porous debris. The integrated model has been implemented into the SCDAP/RELAP5 code for the analysis of the integrity of LWR lower heads during severe accidents. The results of the model indicate that melted core plate material may permeate to near the bottom of a 1m deep hot porous debris bed supported by the lower head. The presence of the relocated core plate material was calculated to cause a 12% increase in the heat flux on the external surface of the lower head.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2000},
month = {4}
}

Conference:
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