Transcript LVR-15 Experience in NRI Řež, plc.

Conclusions from
Quench-03 Test Analyses with
ICARE2 and MELCOR Codes
Jiří Duspiva
Nuclear Research Institute Řež, plc.
Nuclear Power and Safety Division
Dept. of Reactor Technology
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
Outline

Background of Quench analysis in NRI Řež
Quench-03 test analysis with ICARE2

Improved model of Quench-03

Summary and conclusions

(Short summary of 10th QWS presentation)
• Comparison to MELCOR 1.8.5
• Comparison to MELCOR 1.8.5
• Regressive application to Quench-01
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
2
Background
of NRI Quench Analyses




First NRI – Quench activities were performed with MELCOR Code
Own MELCOR input model was developed for Quench-01 [1], successfully
also applied to Quench-06 [ISP-45 Blind phase] calculations
Quench-03 Calculation was last with MELCOR 1.8.5 [2]
•
•
•
Temperature at onset of reflooding higher than Q-01 and Q-06
Temperature escalation was not predicted correctly
Strong underestimation of Hydrogen production
•
•
•
Step 1 – Preparation of model and calculation of Quench-01 test
Step 2 - Sensitivity Study on the change of important parameters
Step 3 – Calculation of Quench-03 test
Under EU Project SARNET in TPA1/JPA1 (WP9: Early Phase of Core
Degradation ST-1 Hydrogen Generation during Core Reflooding) started
application of ICARE2 Code with following schedule [3] and [4]
[1] J. Duspiva: Quench-01 Test Calculation with MELCOR Code, CSARP Meeting, May 7-9, 2001, Bethesda, Maryland
[2] J. Duspiva: Quench-03 Test Calculation with MELCOR Code, 8th International Quench Workshop, Karlsruhe, Germany,
October 29-31, 2002
[3] J. Duspiva: Quench Test Calculations with ICARE2 Code and Comparison with MELCOR Code Results, 10 th International Quench
Workshop, Karlsruhe, Germany, October 26-28, 2004
[4] J. Duspiva: Quench Test Calculations with ICARE2 Code and Comparison with MELCOR Code Results (Quench-01 and Quench-03
Test Analyses), Report NRI Řež, UJV-12204-T, March 2005
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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ICARE2 Input Model
Quench Facility Nodalization


Original model, received from
L. Belovsky (ALIAS CZ), was prepared by G.
Bandini (ENEA)
Macrocomponents
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•
•
•
•
•
•


Unheated rod
8 heated rods of inner ring
12 heated rods of outer ring
3 Corner rods (withdrawal of one corner rod
neglected)
Grid spacers and
Shroud with gap above heated zone
One TH channel – FLUID2 type
41 axial levels
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•
•
Inner Ring Rod Axis
Outer Ring Rod Axis
PZO1
MO2B
MO3B
CLAD1
IE2B
IE3B
CLAD2
CLAD3
1.4
Ax.L. 40
Ax.L. 39
Ax.L. 38
Ax.L. 37
Ax.L. 36
Ax.L. 35
Ax.L. 34
Ax.L. 33
Ax.L. 32
Ax.L. 31
Ax.L. 30
Ax.L. 29
Ax.L. 28
Ax.L. 27
Ax.L. 26
Ax.L. 25
Ax.L. 24
Ax.L. 23
Ax.L. 22
Ax.L. 21
Ax.L. 20
Ax.L. 19
Ax.L. 18
Ax.L. 17
Ax.L. 16
Ax.L. 15
1.3
1.2
GRIDU1
GRIDU3
BSS
BZIRR
1.1
BZIR
BZF5
PZO2
PZO3
BZF4
TUNG2
TUNG3
BZF3
GRIDU2
1.0
0.9
0.8
Ax.L. 14
Ax.L. 13
BZF2
0.7
Ax.L. 12
Ax.L. 11
GRIDM1
GRIDM3
BZF1
0.6
Ax.L. 10
GRIDM2
0.5
Ax.L. 9
0.4
Ax.L. 8
0.3
Ax.L. 7
0.2
GRIDL1
GRIDL3
0.1
4 below heated part
21 in heated part
16 upper plenum
Ax.L. 5
GRIDL2
0.0
MO2A
Ax.L. 4
-0.1
GRIDB1
Ax.L. 3
-0.2
Sensitivity Matrix  Improvements
J. Duspiva
Bundle, Shroud & Central Rod Axis
Ax.L. 41
Ax.L. 6
First test on Quench-01
•
Elevation
[m]
1.5
GRIDL2
Ax.L. 2
MO3A
GRIDL3
IE2A
IE3A
CU2A
CU3A
-0.3
Ax.L. 1
-0.4
-0.47
Central
Unheated Rod
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
Inner Heated
Ring Rod
Outer Heated
Ring Rod
Shroud Wall
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Quench-01
Results of Reference Calculation



Total Hydrogen
production predicted
correctly  tuned up
by external
resistivity
Temperature
profiles also
predicted well until
the beginning of
reflooding
Heat Balance was
checked, based on
methodology from
ISP-45
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Quench-03
Input File Changes

Changes done in comparison with Quench-01
calculation (identical approach as in MELCOR
analyses of Quench-01 and Quench-03 tests)
Redefinition of (initial and boundary conditions)





Power per ring
Inlet temperatures and mass flow rates
(Ar, steam and water)
Initial temperatures in bundle
Time of reflooding beginning
Timestep definition
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Quench-03
Hydrogen Production
Quench-01 like external
Tuned up external
resistivity 3.09 m/rod
resistivity 2.1 m/rod
First step in the input modifications was done in tuning up of external
resistivity  temperature instability in bottom part of bundle
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Quench-03
Temperature Profile at 2600 s
Water injection
Quench-01 like external
Tuned up external
onset
at
2600
s
resistivity 3.09 m/rod
resistivity 2.1 m/rod
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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ICARE2 to MELCOR Comparison
[2] J. Duspiva: Quench-03 Test Calculation with MELCOR
Code, 8th International QUENCH Workshop, Karslruhe
October 29-31, 2002


Similar behaviour of both analyses for H2 production when all settings from Q-01
are applied in Q-03 (change of initial and boundary conditions)
Also temperature evolutions had a lot of similarities
•
•
Relatively good agreement of temperature prediction in lower and middle part of
heated zone
No temperature escalation results in underestimation of H2 production
End of 10th QWS 2004 NRI Contribution Summary
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Identification of Critical Point
Application of ATLAS Postprocessor
GRS postprocessor
ATLAS

ICARE2 results
reprocessing by
MELCOR
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At 2600 s
Significant
underprediction of
temperatures in hot
zone
From analyst point
of view identified
as overestimation
of heat losses
through shroud in
area of hot zone
From Q-03 test
point of view
identified as “loss
of heat removal”
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Modelling Approach Used



More possible ways exist
Definition of material properties was separated for
•
•
BZF2-5
BZF1
Conductivity of solid material was modified for
temperature above 550 K
Final values were defined iteratively based on
temperature profiles at onset
Modification of Zirconia Fibers CDS
950 K
Elevation
[m]
1.5
Bundle, Shroud & Central Rod Axis
Ax.L. 41
Inner Ring Rod Axis
Outer Ring Rod Axis
Q-01 and Q-03
PZO1
MO2B
MO3B
CLAD1
IE2B
IE3B
CLAD2
CLAD3
1.4
Ax.L. 40
Ax.L. 39
Ax.L. 38
Ax.L. 37
Ax.L. 36
Ax.L. 35
Ax.L. 34
Ax.L. 33
Ax.L. 32
Ax.L. 31
Ax.L. 30
Ax.L. 29
Ax.L. 28
Ax.L. 27
Ax.L. 26
Ax.L. 25
Ax.L. 24
Ax.L. 23
Ax.L. 22
Ax.L. 21
Ax.L. 20
Ax.L. 19
Ax.L. 18
Ax.L. 17
Ax.L. 16
Ax.L. 15
1.3
1.2
GRIDU1
GRIDU3
BSS
BZIRR
1.1
BZIR
BZF5
PZO2
PZO3
BZF4
TUNG2
TUNG3
BZF3
GRIDU2
1.0
0.9
0.8
Ax.L. 14
Ax.L. 13
BZF2
0.7
Ax.L. 12
Ax.L. 11
GRIDM1
GRIDM3
BZF1
0.6
Ax.L. 10
GRIDM2
0.5
Ax.L. 9
0.4
0.40
Ax.L. 8
Conductivity [W/m*K]

0.35
0.3
Ax.L. 7
0.30
0.2
Original
0.20
BZF1
Ax.L. 5
0.15
BZF2-5
Ax.L. 4
0.10
GRIDL1
Ax.L. 6
0.25
GRIDL2
0.0
MO2A
-0.1
GRIDB1
Ax.L. 3
-0.2
0.05
GRIDL3
0.1
GRIDL2
Ax.L. 2
MO3A
GRIDL3
IE2A
IE3A
CU2A
CU3A
-0.3
0.00
0
500
1000
1500
Temperature [K]
J. Duspiva
2000
2500
Ax.L. 1
-0.4
610 K Q-01
600 K Q-03
-0.47
Central
Unheated Rod
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
Inner Heated
Ring Rod
Outer Heated
Ring Rod
550 K
Shroud Wall
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Improved Prediction
2500 s
2520
2540
2560
2580
2590
2600
2610
2620
2630
2640
2650
2660
2670
2680
2690
2699
2710
Temperature Profile at ______

Reflooding
phase

Temperature
observations
profiles are in
• Overprediction
agreement of
temperatures in
with measured
bottom
part
values
• Oscillations of
water level
 swollen
Significantly
• Quench
lower front level
remains at bottom


temperature
Continuation of
of Zirconia
calculation
is
fiber
problematiclayers
due to
unconvergency

All threeand
types
too small
timestep
of rod
are
-4
(< 10 degraded,
s)
Calculation
of whole
shroud
Q-03 was not finished
remains intact
and is not planned
 Visualization
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Application of New ZF Properties
to MELCOR Analysis
“Identical” figure of
temperature
profiles with
modified ZrO2 Fiber
Conductivity
At 2600 s
 Significant reduction
of ZF temperatures
as in ICARE2 run
 Slightly
underpredicted
temperatures of hot
zone
 H2 production
underpedicted 22 g
• Reason  trick in
shroud modelling to
allow its oxidation
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Bundle Reflooding
in MELCOR Analysis

At 2725 s
Reflooding phase
observations
• Correct prediction
•


of water level
Agreement in
temperature drop
due to quenching
Rod and shroud
degradations are not
predicted so
intensive as in
ICARE2 run
Code stability – no
termination of run
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Summary and Conclusions

Application of new postprocessing (using GRS ATLAS tool via MELCOR
code) made a possible to identified cause of modelling troubles
•
•
•

Improved modelling resulted in very good agreement in temperature
profiles at the time of water injection onset in ICARE2 analysis
•

Three screens prepared – one of them for both of codes used  direct
comparison
Working term of phenomenon identified: “loss of heat removal through
shroud in hot zone”
Modelling of this feature was done by changing of Zirconia fiber
conductivity
In MELCOR analysis - agreement was not found, but temperature profiles
were improved too  trick in shroud oxidation modelling with fixed heat
transfer coefficient (COR00011 input row)
ICARE2 calculation of reflooding phase results in unconvergency and
timestep reduction, oscillation in swollen water level occurred
•
MELCOR run was more stable during reflooding phase
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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Summary and Conclusions


Application of ICARE2 code allowed to identify cause, which was not
possible to identify with integral code due to its modelling
simplifications, but conclusions are relevant to both of codes (new
features of MELCOR1.8.6 will allow more direct validation on
Quench tests)
Regressive application of Zirconia fiber properties to Quench-01
analysis with ICARE2 code resulted in strong overpediction of
temperatures and hydrogen production
•
•
•

(2)
Phenomenon occurred in Quench-03 test only, not in Quench-01, so it is
not possible to use the same model for analysis of both tests
Final identification and description of phenomenon, which occurred in
Quench-03, should be done by experimenters from FZK, only one of
possible analytical approaches to model this test was presented
Specificity of Quench-03 results from shroud behaviour
•
•
Not objective of Quench program
Unimportant for plant applications  no another analysis are needed
Output from effort is available in Report UJV-12204-T
J. Duspiva
11th International QUENCH Workshop
Karlsruhe, Germany, October 25-27, 2005
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