GAMMA Code for NGNP Air Ingress Analysis

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GAMMA Code for NGNP Air Ingress Analysis

• Chang Oh

RELAP5 Workshop November 8, 2007
2
History of GAMMA Development
Analysis for H2 Production Plant
(High-temperature Steam Electrolysis Process)
INERI Program 2007-2009
Analysis for H2 Production Plant (Thermochemical
Process)
NRL(National Research Lab) Program 2006-2010
PCU System Analysis
Air Ingress Analysis Code
INERI Program 2003-2006
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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

4
Main Characteristics of GAMMA
GAMMA GAs Multicomponent Mixture Analysis

• Transient multi-D fluid and solid treatment
  1D3D
• 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, O2, N2, CO, CO2,
  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 Raphsons 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)

FLUENT Model
GAMMA Model
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Results
Test cases Max. time step Max. time step Computation time Computation time
Test cases GAMMA FLUENT GAMMA FLUENT
Isothermal 0.5 sec 0.2 sec 32 min. 20 hrs
Non-isothermal 0.5 sec 0.2 sec 36 min. 22 hrs
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Validation of GAMMA
P Porous Media
D Diffusion NC Natural Convection
R Radiation C Chemical Reaction
Test Facility D NC R C P etc
1 Pipe Network, NWU O
2 Blowdown, NWU O O
3 Buncan Toors Experiment O
4 Inverse U-tube single/multiple channel test O O
5 Ogawas circular tube test O
6 Takahashis annular tube test O
7 VENTURA pebble bed test O O
8 Inverse U-tube air ingress experiment O O O
9 HTTR simulated air ingress experiment O O O O
10 Vertical slot experiment O O
11 NACOK natural convection test O O
12 SANA-1 afterheat removal test O
13 HTTR RCCS mockup test O O
14 SNU RCCS test O O
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Air Ingress Analyses PBMR 268 MWt
input Conditions Tin/Tout
500/900oC Total Coolant Flow 129 kg/s Cavity
Wall Temp. 50oC (ss), 80oC (tr) water-cooled
RCCS Vault Volume 50,000 m3
? GAMMA System Modeling
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Air Ingress Analyses (Cont) Results
? Air Volume (50,000 m3 German HTR-module Data
in a vault)
He discharge into vault
Onset of natural circulation
Air depletion
Mole Fractions of Gas Species in a Vault and Air
Flow Rate
Temperature Variation in Center Ring
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Experiments for Graphite Oxidation
Experimental Variables
Type 1
Type 2

• Graphite temperature
• Operating pressure
• Oxygen concentration
• Gas velocity
• Gas material
• Graphite material
• Graphite geometry

Type 1
Type 2
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Graphite Oxidation Models
Mass Diffusion
Kinetics
temperature concentration
air flow rate
Moisture Effect
Graphite Oxidation Models
Moisture
degree of burn-off
Burn-off Effect
size shape
C/CO2 reaction
C/CO2 reaction
Geometrical Effect
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Gas Turbine Analyses
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Main Characteristics of Throughflow Analysis

• 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

Meridional plane of compressor
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 -gt 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
Parameters JAEA KAIST Deviation ()
Pressure ratio 1.997 1.977 -1.002
Temperature ratio 1.359 1.350 -0.662
Polytropic efficiency () 90.5 90.7 0.221
Shaft Work (MW) 251 246 -1.992
Parameters JAEA KAIST Deviation ()
Pressure ratio 1.870 1.857 -0.695
Temperature ratio 1.269 1.258 -0.867
Polytropic efficiency () 92.8 92.8 0
Shaft Work (MW) 530 528 -0.377
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Off-design Performance of Compressor
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Work Diagram of RELAP5/GAMMA Interfacing
Interfacing Using PVMEXEC Or DLL
GAMMA
RELAP
5
-
3
D

(
1
st step
-
)
2006
2008
Hydrogen Model
Dynamic Model
-
Process models

-
Diffusion for multiple components
-
Busen process
,
-
HI process
,
-
Three dimensional heat transfer capability
-
H
2
SO
4
process
-
Physical models

-
Component models
-
mass transfer coeff
.
,
Interfacing
-
pressure drop
,
-
turbomachinery
(
2
nd step

2009
-
2011
)
-
entrainment
-
weeping
,
-
shaft
-
generator
-
flooding
,
etc
-
heat exchangers
-
Thermodynamic property models

-
valve
-
Controller models
-
K
-
value
,
-
activity coeff
.
-
bypass
-
vapor pressure
,
-
inventory
-
physical property
-
reactivity
IHX Coupling Model
1
st step
2
nd step
(
2006
-
2008
)
(
2009
-
2011
)
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RELAP5/GAMMA Interfacing