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GAMMA Code for NGNP Air Ingress Analysis Chang Oh RELAP5 Workshop November 8, 2007

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History of GAMMA Development Air Ingress Analysis Code PCU System Analysis Analysis for H2 Production Plant (High-temperature Steam Electrolysis Process) NRL(National Research Lab) Program: 2006-2010 INERI Program: 2003-2006 INERI Program: 2007-2009 Analysis for H2 Production Plant (Thermochemical Process)

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What is air-ingress” Why a new code? -Air-ingress is a design- based serious accident in VHTR. -Accelerating heatup of core -Mechanical degradation of bottom structural graphite -Releasing toxic gas

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Main Characteristics of GAMMA GAMMA: GAs Multicomponent Mixture Analysis Transient multi-D fluid and solid treatment: 1D~3D Various coordinates: Rectangular & Cylindrical 1D/3D merging: some components can be treated 1D while others are treated 2D or 3D. ICE numerical scheme: matrix reduction, quick convergence, powerful for transient analysis Treatment of 6 gas species: He, O 2, N 2, CO, CO 2, H2O Chemical reaction models: homogeneous, heterogeneous Diffusion models: full multicomponent diffusion, effective diffusion, tracer diffusion models Surface-surface radiation model Porous body treatment in the core: effective thermal conductivity

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Governing Equations of GAMMA Mass Conservation: mixture, He, N2, O2, CO, CO2, H2O Momentum Conservation Energy Conservation

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Numerical Features of GAMMA Semi-implicit & Donor Cell Scheme, Staggered Mesh Layout Linearization by Newton Raphson’s Method Matrix Reduction by ICE (Implicit Continuous Eulerian) 10N 10N N N Pressure Matrix

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Numerical Tests: GAMMA and FLUENT Inverse U-tube Experiments in Binary Mixture [Takeda & Hishida (1991)] GAMMA Model FLUENT Model

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Results Test cases Max. time stepComputation time GAMMAFLUENTGAMMAFLUENT Isothermal0.5 sec0.2 sec32 min.20 hrs Non- isothermal 0.5 sec0.2 sec36 min.22 hrs

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Validation of GAMMA Test FacilityDNCRCPetc 1Pipe Network, NWU O 2Blowdown, NWUO O 3Buncan & Toor’s ExperimentO 4Inverse U-tube single/multiple channel testOO 5Ogawa’s circular tube testO 6Takahashi’s annular tube testO 7VENTURA pebble bed testOO 8Inverse U-tube air ingress experimentOOO 9HTTR simulated air ingress experimentOOO O 10Vertical slot experimentOO 11NACOK natural convection testOO 12SANA-1 afterheat removal testO 13HTTR RCCS mockup testOO 14SNU RCCS testOO * D : Diffusion * NC : Natural Convection * R: Radiation * C: Chemical Reaction * P: Porous Media

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Air Ingress Analyses: PBMR 268 MWt GAMMA System Modeling input Conditions: Tin/Tout : 500/900 o C Total Coolant Flow: 129 kg/s Cavity Wall Temp. : 50 o C (ss), 80 o C (tr) water-cooled RCCS Vault Volume : 50,000 m 3

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Air Ingress Analyses (Con’t): Results Mole Fractions of Gas Species in a Vault and Air Flow Rate Temperature Variation in Center Ring Air Volume (50,000 m 3 : German HTR-module Data in a vault) He discharge into vault Onset of natural circulation Air depletion

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Experiments for Graphite Oxidation Type 1Type 2 Type 1Type 2 Graphite temperature Operating pressure Oxygen concentration Gas velocity Gas material Graphite material Graphite geometry Experimental Variables

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Graphite Oxidation Models Kinetics Mass Diffusion Graphite Oxidation Models Burn-off Effect Geometrical Effect C/CO2 reaction air flow rate temperature concentration degree of burn-off size & shapeC/CO 2 reaction Moisture Effect Moisture

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Gas Turbine Analyses

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Main Characteristics of Throughflow Analysis Meridional plane of compressor 1.to use natural coordinates (q,m) instead of cylindrical coordinates (r, ,z): one transformed momentum equation in the q direction. 2. to produce the radial equilibrium equation combining the one transformed momentum and energy equations through eliminating pressure: radial equilibrium equation and continuity equation m: streamline tangential direction at the edges of blades q: blade-edge directions

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Development of SANA Gas turbine analysis (SANA: Streamline curvature Analysis based on Newton-Raphson numerical Application) Throughflow analysis based on Newton-Raphson method : Numerically robust and efficient method 3D complex problem -> axisymmetric 2D problem (radially nonunform axial velocity distribution) Validation of SANA Coupling of SANA with GAMMA Implementation into transient system codes

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Performance of GTHTR300 Gas Turbine

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Design-point Performance ParametersJAEAKAISTDeviation (%) Pressure ratio1.8701.857-0.695% Temperature ratio1.2691.258-0.867% Polytropic efficiency (%)92.8 0% Shaft Work (MW)530528-0.377% ParametersJAEAKAISTDeviation (%) Pressure ratio1.9971.977-1.002% Temperature ratio1.3591.350-0.662% Polytropic efficiency (%)90.590.70.221% Shaft Work (MW)251246-1.992%

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Off-design Performance of Compressor

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Work Diagram of RELAP5/GAMMA Interfacing GAMMA Dynamic Model -Component models -turbomachinery -shaft-generator -heat exchangers -valve -Controller models -bypass -inventory -reactivity RELAP5-3D Hydrogen Model -Process models: -Busen process, -HI process, -H2SO4process -Physical models: -mass transfer coeff., -pressure drop, -entrainment-weeping, -flooding,etc -Thermodynamic property models: -K-value, -activity coeff. -vapor pressure, -physical property IHX Coupling Model Interfacing Using PVMEXEC Or DLL (1st step 2006 - 2008 ) Interfacing (2nd step:2009-2011) 1st step (2006-2008) 2nd step (2009-2011) - Diffusion for multiple components - Three dimensional heat transfer capability

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RELAP5/GAMMA Interfacing

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