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CAPE-B: Critical Power Analysis Code for BWR Fuel Bundle
- Evaluation Method Analytical Step
1. Fuel Bundle
2. Spacer Effect
Calculation Method
3-D Subchannel Analysis
with Drift-flux Model
3-D Liquid Droplet Transport Analysis
In Turbulent Steam Flow
3. Each Subchannel
Liquid Film Flow Analysis
4. Detection of Dryout
Liquid Film Flow Rate = 0
IMPACT
CAPE-B: Verification of Subchannel Analysis Model
(1. Analysis of the test conducted by Lahey, et al.)
 Pressure : 6.9 Mpa
 Number of axial subchannel division : 50
4000
(Standard deviation)
s=7%
+s
-s
3000
2000
1000
0
:Corner
:Side
:Inner
1000 2000 3000 4000
Measured mass flux (kg/m2s)
IMPACT (a) Comparison of mass flux
Calculated quality
Calculated mass flux (kg/m2s)
Un-heated test (4 test runs)
Average mass flux : 651-2671 kg/m2s
Inlet subcooling : 1174 kJ/kg
Heated test (13 test runs)
Average mass flux : 719-1464 kg/m2s
Inlet subcooling : 68-603 kJ/kg
Heated length : 1.83 m
Power distribution : Uniform
Heat flux : 710-2130 W/m2
0.5 (Measurement error)
e=0.024
0.4
+e
-e
0.3
0.2
:Corner
:Side
:Inner
0.1
0
0.1 0.2 0.3 0.4
Measured quality
0.5
(b) Comparison of steam quality
CAPE-B: Verification of Subchannel Analysis Model
(2. Analysis of NUPEC full scale bundle test)
: Present calculation
: COBRA-BWR
Regional average void fraction
0.8
Radial power distribution
: 1.30
: 1.15
: 0.90
: 0.45
Test data
0.6
0.4
Pressure : 7.2 Mpa
Mass flow rate : 1562 kg/m2s
0.2 Inlet subcooling : 50.2 kJ/kg
Axial power distribution : Uniform
Number of axial subchannel division : 48
PERI
IMPACT
IN-2
IN-1
Region in bundle
IN-3
PERI
IN-1
IN-2
IN-3
CAPE-B: Concept of Liquid Film Flow Analysis
Fuel rod
Dryout
Liquid film
Heat transfer to liquid film
Outflow from the mesh
(=Inflow to the next mesh)
Entrainment rate: E
dGf
)
Gf +
dz
dz
dGf pe
= (D- E - B)
dz
A
(
Evaporation rate: B
dz
Deposition rate: D
Mesh height
Liquid droplet
Inflow to the mesh: Gf
IMPACT
CAPE-B: Verification of Spacer Effect Analysis Model
(Analysis of the test conducted by Nagayoshi, et al.)
Hot wire probe
10 mm
Plate spacer
(Thickness: 0.5, 1.0 mm)
Flow
Rectangular duct
(a) Test section
50 mm
Flow
10 mm
70 meshes
30 mm
Rectangular duct
80 mm
42 meshes
Z=0
Plate spacer (Thickness: 0.5, 1.0 mm)
IMPACT
(b) 2-dimensional analysis region
Z
CAPE-B: Turbulent Enhancewment due to the Spacer
(Analysis of the test conducted by Nagayoshi, et al.)
Increment ratio of turbulent fluctuation u'/u'∞
4
Thickness Exp.
0.5 mm
1.0 mm
3
2
1
0
IMPACT
Cal.
10
20
30
40
Distance from the edge of the spacer (mm)
50
CAPE-B: Test analysis condition for model validation
NUPEC 88
Bundle No. C2A
Bundle No. III
Ferrule Spacer,
Grid Spacer,
1 W/R
2 W/Rs
Bundle Type
EPRI 44
Bundle No. 301
Grid Spacer,
no W/R
Pressure (Mpa)
5.5, 7.2, 8.6
7.2, 8.6
4.1, 6.9, 8.6
Mass flux (kg/m2s)
590-1,910
570-1,690
700-1,750
Inlet subcooling (kJ/kg)
20-130
10-125
50-610
Heated length (m)
3.7
3.7
1.8
Power
Distribution
Axial
Radial
24-step chopped cosine with p/f of 1.4
Uniform
Local p/f: 1.30
Local p/f: 1.18
Local p/f: 1.02
Number of data points
70
72
38
Subchannel Axial
Division
Radial
72
80
72
81
72
25
Spacer effect
Analysis
IMPACT
Coordinates Cylindrical
Mesh division 206488
W/R: Water Rod,
Cartesian
404090
p/f: peaking factor
Cartesian
404090
CAPE-B: Two Typical Spacer Types
1/4 Subchannel
Fuel rod
Grid type spacer
IMPACT
1/4 Subchannel
Fuel rod
Ferrule type spacer
CAPE-B: Validation analysis for BWR models
(Analyses of the NUPEC 88 and EPRI 44 tests)
Calculated critical power (MW)
12
10
Average difference : 0.5% s
s=5.1% (Standard deviation)
+s
-s
8
6
4
2
Pressure : 6.9 - 7.2 MPa
Number of data points : 116
0
IMPACT
2
4
6
8
10
Measured critical power (MW)
12
(a) Comparison at rated pressure
CAPE-B: Validation analysis for BWR models
(Analyses of the NUPEC 88 and EPRI 44 tests)
Calculated critical power (MW)
12
10
Average difference : - 0.3% s
s =6.3% (Standard deviation)
+s
-s
8
6
4
2
Pressure (MPa)
: 8.6
: 6.9 - 7.2
: 5.5
: 4.1
Number of data points : 166
0
IMPACT
2
4
6
8
10
Measured critical power (MW)
(b) Comparison with all data
12
CAPE-B: Comparison of dryout locations
0.98
0.99
1.15
0.98
0.98
1.18
1.10
1.10
1.15
1.15
0.60
1.15
1.18
1.10
0.60
0.98
1.15
0.98
0.98
0.98
0.98
0.60
1.10
0.98
WR
0.98
0.98
1.10
WR
0.60
0.98
1.10
1.10
0.98
0.98
0.98
1.18
1.30
0.75
0.45
0.99
1.15
0.99
0.89
0.99
0.89
1.18
1.30
1.18
0.89
0.99
0.89
1.18
1.30
0.99
0.89
0.99
0.89
0.99
1.15
0.75
0.45
0.99
0.89
0.99
0.89
0.99
0.89
0.99
0.89
1.18
1.30
0.99
1.15
0.75
0.45
0.99
0.89
0.99
0.89
0.75
0.45
0.99
1.15
0.99
1.15
1.18
1.30
0.99
1.15
0.99
1.15
0.99
1.15
0.99
1.15
0.99
1.30
IMPACT
Dryout locations
Bundle Test
III and C2B
C2A
Cal.
Bundle III
WR : Water rod
0.60
0.98
0.98
0.99
1.15
Bundle C2A, C2B
CAPE-B: Effect of radial power peaking
Pressure : 7.2 MPa
Inlet subcooling : 50.2 kJ/kg
10
Radial power peaking
factor : 1.18
Critical power (MW)
9
8
7
Radial power peaking
factor : 1.30
6
Bundle No. Spacer Exp. Cal.
C2B
5
~
~
IMPACT
~~
0
C2A
500
Ferrule
type
1000
1500
Mass flux (kg/m2s)
2000
CAPE-B: Critical power difference by spacer type
Critical power (MW)
10
Pressure : 7.2 MPa
Inlet subcooling : 50 kJ/kg
9
8
7
6
5
Bundle No. Spacer Exp. Cal.
Ferrule
C2B
III
~
~
500
IMPACT
Grid
1000
1500
Mass flux (kg/m2s)
2000
CAPE-B: Droplet deposition characteristics
Spacer Location
Droplet transport rate (m/s)
: Ferrule
: Grid
0.3
Ferrule Spacer
0.2
0.1
Grid Spacer
0
IMPACT
50
100
150
Axial distance (mm)
200
250