SWR-1000: NRC-Visit
Preparation of the External Vessel Cooling Test
SWR 1000 - Exterior Vessel Cooling
Inlet of the water inthe gap betweenRPV and insulation
Decoupling of Flow Conditions and Heat Transfer
Water / Air-Experiments Scale 1 : 10Investigation of the global flow conditions anddetermination of requirements for the design of asegment
Water / Air-Experiments with a SectionDesigning of in- and outlets in order to reach asimilar flow behaviour as in the global model
Water / Steam-Experiments with a SectionMeasuring the Critical Heat Flux in a 1:1section model installed in the BENSON test rig- a flexible water / steam test loop
Global Model
Setup of the RPV:
• Air injection through aporous structure atthe bottom
• Eight chambers withadjustable air supply
Setup of the insulation:
• Transparent materialincluding CRD andpump housings
• Impedance probes formeasuring theadequate gas height
• Fiber optic probe formeasuring the void
Phenomenology
• Circulation can be observedThe water / gas mixture will move upwards and willbe separated at the swell level. The water will flowback
• Counter current flow can be observed at the bottomThe water/air mixture flows upwards around theRPV, single-phase water flows downwards aroundthe insulation. A portion penetrates in the water/airmixture
• Flow is approximately rotational symmetric
• Bubbles in the water/air test grow approximatelysimilar to those of boiling tests
• Rotational symmetric slug bands will be formed. Inthe case of flow without insulation, they are strongerthan in the case with insulation
• b
Phenomenology - Global Model in Operation
Phenomenology - Counter Current Flow
Phenomenology - Flow around the CRD Housings
Phenomenology - Movement of Bubbles
Fiber Optic Probe
Local Void Fraction Determination
0
0.2
0.4
0.6
0.8
1
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Distance [mm]
Vo
id F
ract
ion
[-]
1,5
2
2,5
3
3,5
4
V o
l t g
e [ V
]
1,5
2
2,5
3
3,5
4
V o
l t a
g e
[ V
]
1,5
2
2,5
3
3,5
4
V o
l t a
g e
[ V
]
Time [s] →
Local Void Fractions at different Inclinations
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 2 4 6 8 10 12 14 16
Distance from RPV [mm]
Lo
cal V
oid
Fra
ctio
n [
-]
Inclination 7°Inclination 21°
Dimension and Positions of the Probes
Average Gas Height measured with Fiber Optic Probe and Impedance Probe
0
1
2
3
4
5
0 50 100 150 200 250
Gas Mass Flow [kg/h]
Gas H
eig
ht [m
m]
Fiber Optical Probe= dh0
0.2
0.4
0.6
0.8
1
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Distance [mm]
Vo
id F
ract
ion
[-]
∫
Impedance Probe
Gas Height Distribution
0,0 3,6 7,2 10,8 14,4 18,0 21,6 25,20,0
3,6
7,2
10,8
14,4
18,0
21,6
25,2
9 -10
10-11
[mm]Height
0 - 1
1 - 2
2 - 3
5 - 6
3 - 4
4 - 5
6 - 7
7 - 8
8 - 9
Decay HeatAdequate Gas Height at a Mass Flux of Y
Axi
s [c
m]
X Axis [cm]
Adequate Gas height between CRD Housing No. 128 and No. 129 (5 -6 mm)
0,0 3,6 7,2 10,8 14,4 18,0 21,6 25,20,0
3,6
7,2
10,8
14,4
18,0
21,6
25,2
9 -10
10-11
[mm]Height
0 - 1
1 - 2
2 - 3
5 - 6
3 - 4
4 - 5
6 - 7
7 - 8
8 - 9
Decay HeatAdequate Gas Height at a Mass Flux of Y
Axi
s [c
m]
X Axis [cm]
Adequate Gas height between CRD Housing No. 131 and No. 132 (6 -7 mm)
Positions of the LDA Measurements
Velocity Distribution as the Function of the Height
-0.15
-0.05
0.05
0.15
0.25
0.35
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Dimensionless Distance [-]
No.132 and Position M
No.131 and No.132
No.130 and No.131
No.129 and No.130
No.128 and No.129
Local Velocities
-0.15
-0.05
0.05
0.15
0.25
0.35
0 0.2 0.4 0.6 0.8 1
Dimensionless Distance [-]
Approximation curve between CRD Housing No. 128 and No. 129
Corrected measurement curve based on a Gaussian probability
Estimated local velocity distribution
Water Mass Flow Balance
-0.12
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0 0.1 0.2 0.3 0.4 0.5 0.6
Dimensionless Distance [-]
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95
Dimensionless Distance [-]
( ) ( ) ( )( )
( ) ( ) ( )( ) bvvxxM
bvvxxM
velocitiespositivewithareathein
positionsofNumber
iLiiiiiioutW
velocitiesnegativewithareathein
positionsofNumber
iLiiiiiiinW
−⋅+−⋅−=
=−
−+−−=
∑
∑
−
=+++
−
=+++
1
1111;
!1
1111;
2111
)1(21
11
ρεε
ρεε
&
&
Gas Mass Flow Balance
0
0.1
0.2
0.3
0.4
0.5
0.6
0.0000 0.0050 0.0100 0.0150 0.0200 0.0250
Air Mass Flow [kg/s]
Vo
id F
ract
ion
[-]
between CRD Housing No. 128 and No. 129
between CRD Housing No. 131 and No. 132
0.35
0.28
0.0049 0.0094
2h
hG=ε
Results of the Mass Flow Balances
Kammerung zur Lufteindüsung
Pos. 131-132 Pos. 128-129
Border of air injection chambers
Pos. 131-132 Pos. 128-129
Position 128-129 Position 131-132
Water Mass Flow, Inlet [kg/s] 1,19 1,36
Water Mass Flow, Outlet [kg/s] 1,40 1,59
Ratio Water Mass Flow Out/In 1,18 1,17
Air Mass Flow, Injected [kg/s] 0,0043 0,0085
Air Mass Flow, Acc. Fig. 13[kg/s] 0,0049 0,0094
Ratio Out/In 1,14 1,11
Decoupling of Flow Conditions and Heat Transfer
Water / Air-Experiments Scale 1 : 10Investigation of the global flow conditions anddetermination of requirements for the design of asegment
Water / Air-Experiments with a SectionDesigning of in- and outlets in order to reach asimilar flow behaviour as in the global 1 : 1 model
Water / Steam-Experiments with a SectionMeasuring the Critical Heat Flux in a 1:1Section Model installed in the BVS - a flexibleWater / Steam-Test Loop
Scaling Procedure and Intention
Steam generation
Air injection
Procedure:
•Void measurements in the model
•Approximation of drift flux correlation parameters
•Calculation of the void fraction based on the new correlation
•Calculation of the air mass flow with similar void fraction
Inlet of the waterin the gapbetween RPV andinsulation
Void Fraction Measurement Method
1,1Φl 1,2Φl 2,1Φl 2,2Φl
( ) ( )( ) ( ) )( 2,11,12,12,21,11,2
2,12,21,11,2
ΦΦΦΦΦΦ
ΦΦΦΦ
−+−−−−−−
=llllll
llllε
Measured Void Fraction and Developed Correlation
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0 0.002 0.004 0.006 0.008 0.01 0.012 0.014
Mass Flow [kg/s]
Void
Fra
ctio
n [-]
Experiment
Drift-FluxC0 = 3,03654
0,25
2l
glgi ñ
)ñ(ñ*g*ó*0,77575u
−=
1
..hom
0
*
*
−
+=mx
uC gigρε
ε
1
.
25,0
2
)(***77575,0*
03654,3
−
−
+=m
g
l
glg ρ
ρρσρ
ε
Mass Flows for the Tests with the Global Model
125,0
2
/
(***77575,0*
03654,3
−
−
+=AM
g
g
l
gig
&ρ
ρρσρ
ε
SWR 1000, Original
• Properties of Water/Steam (P =2-5 bar)
• Mass flux (P =2-5 bar, Q =4,5;9;13,5 MW)
SWR 1000, Model
• Properties of Water/Air (P=1 bar)
• Void (ε =0,16;0,24;0,28)
Void εAir Mass Flow
Q P 2 [bar] 3 [bar] 4 [bar] 5 [bar]4.5 [MW] 0.2224 0.1956 0.1777 0.1598
9 [MW] 0.2655 0.2454 0.2309 0.2152
13,5 [MW] 0.2839 0.2682 0.2564 0.2433
Void ε M [kg/s]
0.16 0.0100.24 0.0290.28 0.061
Kammerung zur Lufteindüsung
Comparison of Void Trends - Model (Air 1 bar) and „Original“ (Steam 3 bar)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
Steam Mass Flow [kg/s]
vertical flow path
between CRD Housing No. 128 and No. 129
between CRD Housing No. 131 and No. 132
0
0.1
0.2
0.3
0.4
0.5
0.6
0.000 0.005 0.010 0.015 0.020 0.025 0.030
Air Mass Flow [kg/s]
Vo
id F
ract
ion
[-]
Corresponding mass flows according mass sources
(injection / evaporation) for the 100% decay heat case
Measurement of Safety Margins
M
M
M
M
M
Test Vessel
Heater
TrickleCooler
Piston Pump
ReductionValve
Heater
Feedwater CirculationPump
Pressurizer
Main Cooler
Spray Condensor
Aim of the experiments:
Measurement of the Critical Heat Fluxabove decay heat
Procedure:• Implementation of a 1:1 scaled segment
in the BVS by considering the in- andoutflow conditions evaluated from thewater / air - experiments
• Instrumentation of the RPV-wall withthermocouples in order to identify thelocation of the boiling crisis (CHF)
• Adjusting the mass flow in such a waythat the feed water mass flow is equal tothe evaporated
• Increasing the heat input stepwise until aboiling crisis-occurred or a relevant safetymargin is reached.
Conclusions and Consequences
• The natural circulation inside the gap between theinsulation and RPV is very strong - compared to thewater supply of the external circulation. Thus, it isnecessary to simulate the internal circulation in awater steam experiment.
• The flow experiments indicate almost rotational symmetricflow conditions.
The effect of flow and heating conditions is unknown, whichmight be influenced by the flow orientation from the centreposition:
• The effect of a straight-line configuration will be lower flowresistance - compared to a non-straight-line configuration -and herewith a higher mass flows in this area.
• The effect of a non-straight-line configuration will be a betterheat transfer behaviour - compared to a straight line configuration.
Conclusion: There will be no significant cross flow between thedifferent orientations if the flow conditions are almost similar forboth extreme configurations. In this case it is conservative touse the straight line configuration for a heatable test section.
Straight-Line Configuration
Non-Straight-LineConfiguration
Global and Section Model Measurements
-0.15
-0.05
0.05
0.15
0.25
0.35
0.45
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
X Dimensionless Distance [-]
Global Model
Section Model
Global Model
Section Model
Heatable Section Model - Top View
Bordersof a comparable section
Heatable Section Model - Side View
Heatable Section Model - Heating Concept
Heatable Section Model - CRD Housing connection
10
Tube20
2
External Vessel Cooling Test- Test Objective
Identification of the safety margins of the exterior cooling
concept of the RPV, taking into consideration the influence
of the control rod drive housings
Test Vessel
Heater
TrickleCooler
PistonPump
ReductionValve
Heater
Feedwater Pump
Pressurizer
Main Cooler
SprayCondenser
External Vessel Cooling Test- Manufacturing, Heating Wires (1)
0.00
100.00
200.00
300.00
400.00
500.00
600.00
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Segment No. [-]
Hea
t F
lux
[kW
/m2]
Heat Flux Decay HeatDesign Max. Pos. Heat Flux
External Vessel Cooling Test- Manufacturing, Heating Wires (2)
External Vessel Cooling Test- Measuring Equipment, Pressure/Level
Pressure differences shall be measured at three different levels
l Each of the pressure and pressure drop sensors has to be checked against acalibrated pressure checking device or a water column
l The aim of these measurements is to measurethe water level. Therefore, an accuracyof +/- 2% can be accepted
External Vessel Cooling Test- Measuring Equipment, Mass Flow
The inlet mass flow will be measured via an orifice. This measurement will bechecked via the measurement of the time to fill a defined volume of 60 liters
l The orifice should be chosenin a way that a mass flowcould be measured from0.4 to 0.0025kg/s at 104°C
l The aim of these measurementsis to check, whether the testobject will be supplied withalmost constant flow conditions.Therefore, an accuracy of+/- 4% can be accepted
External Vessel Cooling Test- Measuring Equipment, Inlet Temperature
The inlet temperature measurement will be checkedvia measuring the boiling temperature at ambientconditions. An accuracy of +/- 2K can be accepted
External Vessel Cooling Test- Measuring Equipment, Heated Surface (1)
> The temperature measurements of the heated surface will be checked basedon plausibility
l Plausibility check is described in the Test Procedure (FANPTGT1/02/e42)
l Installation has to be done and checked according to the respectivedrawing
External Vessel Cooling Test- Measuring Equipment, Heated Surface (2)
External Vessel Cooling Test- Measuring Equipment, Power Supply
The measurement of voltage andcurrent supplying the heating wiresis part of the BENSON test riginstrumentation.l The functioning of this has been
checked during test running inAugust 2002
l Within further tests in the followingyears this standard instrumentationwill be checked regularly again
External Vessel Cooling Test Data Acquisition Software (1)
Online display
External Vessel Cooling Test- Data Acquisition Software (2)
"Quicklook"