SIMULATION OF CORE MELT POOL FORMATION IN A REACTOR PRESSURE VESSEL LOWER HEAD USING AN EFFECTIVE CONVECTIVITY MODEL

The present study is concerned with the extension of the Effective Convectivity Model (ECM) to the phase-change problem to simulate the dynamics of the melt pool formation in a Light Water Reactor (LWR) lower plenum during hypothetical severe accident progression. The ECM uses heat transfer characteristic velocities to describe turbulent natural convection of a melt pool. The simple approach of the ECM method allows implementing different models of the characteristic velocity in a mushy zone for non-eutectic mixtures. The Phase-change ECM (PECM) was examined using three models of the characteristic velocities in a mushy zone and its performance was compared. The PECM was validated using a dual-tier approach, namely validations against existing experimental data (the SIMECO experiment) and validations against results obtained from Computational Fluid Dynamics (CFD) simulations. The results predicted by the PECM implementing the linear dependency of mushy-zone characteristic velocity on fluid fraction are well agreed with the experimental correlation and CFD simulation results. The PECM was applied to simulation of melt pool formation heat transfer in a Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) lower plenum. The study suggests that the PECM is an adequate and effective tool to compute the dynamics of core melt pool formation.

[1]  O. Kymäläinen,et al.  In-vessel coolability and retention of a core melt , 1997 .

[2]  Frank P. Incropera,et al.  Convective Transport Phenomena and Macrosegregation During Solidification of a Binary Metal Alloy: II—Experiments and Comparisons With Numerical Predictions , 1994 .

[3]  T. W. Clyne.  Numerical modelling of directional solidification of metallic alloys , 1982 .

[4]  T. G. Theofanous,et al.  The first results from the ACOPO experiment , 1997 .

[5]  V. Voller,et al.  A fixed grid numerical modelling methodology for convection-diffusion mushy region phase-change problems , 1987 .

[6]  M. Okada,et al.  Analysis of heat transfer during melting from a vertical wall , 1984 .

[7]  Ephraim M Sparrow,et al.  ANALYSIS OF MULTIDIMENSIONAL CONDUCTION PHASE CHANGE VIA THE ENTHALPY MODEL. , 1975 .

[8]  Vaughan R Voller,et al.  Modelling the mushy region in a binary alloy , 1990 .

[9]  B. R. Sehgal,et al.  Recursively coupled thermal and mechanical FEM-analysis of lower plenum creep failure experiments , 2006 .

[10]  T. C. Chawla,et al.  Heat Transfer From Vertical/Inclined Boundaries of Heat-Generating Boiling Pools , 1982 .

[11]  V. Voller,et al.  ERAL SOURCE-BASED METHOD FOR SOLIDIFICATION PHASE CHANGE , 1991 .

[12]  V. G. Asmolov,et al.  Challenges left in the area of in-vessel melt retention , 2001 .

[13]  H.-H. Reineke,et al.  TURBULENT BUOYANCY CONVECTION HEAT TRANSFER WITH INTERNAL HEAT SOURCES , 1978 .

[14]  Chi Thanh Tran,et al.  An effective convectivity model for simulation of in-vessel core melt progression in a boiling water reactor , 2008 .

[15]  B. R. Sehgal,et al.  Heat Transfer Processes in Reactor Vessel Lower Plenum During Late Phase of In-Vessel Core Melt Progression , 2002 .

[16]  Alexei Miassoedov,et al.  Results of the LIVE-L 2 Experiment on Melt Behaviour in RPV Lower Head Performed Within the LACOMERA Project at the Forschungszentrum Karlsruhe , 2007 .

[17]  F. B. Cheung,et al.  Modeling of heat transfer in a horizontal heat-generating layer by an effective diffusivity approach , 1994 .

[18]  Marcel Lacroix,et al.  NUMERICAL STUDY OF NATURAL-CONVECTION-DOMINATED MELTING INSIDE UNIFORMLY AND DISCRETELY HEATED RECTANGULAR CAVITIES , 1998 .

[19]  Chi Thanh Tran,et al.  Analysis of melt pool heat transfer in a BWR lower head , 2006 .

[20]  O. Kymäläinen,et al.  In-vessel retention of corium at the Loviisa plant , 1997 .

[21]  Francis A Kulacki,et al.  Steady and transient thermal convection in a fluid layer with uniform volumetric energy sources , 1977, Journal of Fluid Mechanics.

[22]  Won Soon Chang,et al.  A numerical analysis of Stefan problems for generalized multi-dimensional phase-change structures using the enthalpy transforming model , 1989 .

[23]  Sevostian Bechta,et al.  Partitioning of Zr, U and FP between Molten Oxidic and Metallic Corium , 2004 .

[24]  Ching-Jenq Ho,et al.  Numerical simulation of melting of ice around a horizontal cylinder , 1986 .

[25]  Truc-Nam Dinh,et al.  The investigation of turbulence characteristics in an internally-heated unstably-stratified fluid layer , 1997 .

[26]  Christophe Journeau,et al.  Viscosity models for corium melts , 2001 .