SCDAP/RELAP5 Modeling of Movement of Melted Material through Porous Debris in Lower Head (Rev. 2)
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 my permeate in about 120 s to the bottom of a 1 m deep hot porous debris bed supported by the lower head. The presence of the relocated core plate material at the bottom of the debris bed decreases the thermal resistance of the interface between the debris bed and the lower head. This report is a revision of the report with the identifier of INEEL/EXT-98-01178 REV 1, entitled "SCDAP/RELAP5 Modeling of Movement of Melted Material Through Porous Debris in Lower Head."
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- DOE - EM
- DOE Contract Number:
- DE-AC07-99ID-13727
- OSTI ID:
- 910650
- Report Number(s):
- INEEL/EXT-98-01178; TRN: US200802%%27
- Country of Publication:
- United States
- Language:
- English
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SCDAP/RELAP5 Modeling of Movement of Melted Material Through Porous Debris in Lower Head
SCDAP/RELAP5 modeling of movement of melted material through porous debris in lower head
Related Subjects
ACCIDENTS
CERAMICS
NUMERICAL SOLUTION
PARTICLE SIZE
PERMEABILITY
PLATES
POROSITY
SATURATION
SIMULATION
THERMAL CONDUCTIVITY
TRANSPORT
TURBULENCE
VISCOSITY
ceramic porous debris
debris porosity.
melted core plate
Melted metallic materiall