Experiences of TRAC-P code at INS/NUPEC€¦ · Experiences of TRAC-P code at INS ... Evaluation...
Transcript of Experiences of TRAC-P code at INS/NUPEC€¦ · Experiences of TRAC-P code at INS ... Evaluation...
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Experiences of TRAC-P code
at INS/NUPEC
Fumio KASAHARA(E-mail : kasahara@nupec or jp)
Institute of Nuclear Safety (INS)Nuclear Power Engineering Corporation (NUPEC)
Exploratory Meeting of Experts on BE Calculations and Uncertainty Analysisin Aix en Provence, May 13-14, 2002
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Contents
1. Preparation of the input data with Fine noding model
2. Large break LOCA analysis by Fine noding model
3. Uncertainty Methods Study by Coarse noding model
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1. Preparation of the input data with Fine noding model
(1) Noding
We have been prepared the system analysis noding ofJapanese 4-loop PWR.
It is constituted from 3-D VESSEL and 4 primary coolantloops.
And based on the RELAP5 code input data that we usefor the demonstration analysis.
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1. Preparation of the input data with Fine noding model
Fig.1 4-Loop PWR Fine Noding(81)
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(11)(51)
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(13) (14) (15)
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J47 J50
J49
J48
J2J3J1
J6J28J5
J4
J31
J29
J27
J30
J58J55
J57
J56
J15 J14
J17 J38 J18
J13
J40
J37J41
J39
J16
(56)(58)
(57)(31)
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(33)(32)
(34) (35)
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Loop 1
Loop 3
Loop 2
Loop 4
(44)(45)J63 J64 (43)
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(60)(41)
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J19
J63
J45
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J44
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J22
J21J20
J60
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J61
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J24
J34
J32 J36
J33J12 J11
J10J35
J8 J9
J52
J26
J25J7
J51
J53
(82)
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(21) (54)
(55)(80)
(2)
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(22)(24) (23)(25)
(86)(71)
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(90)
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(N) : Com ponent No.Jn : Junction No.
(Broken Loop)
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1. Preparation of the input data with Fine noding model
Fig.2 Reactor Vessel Fine Noding
Loop 1
Loop 4(Broken Loop)
Loop 3
Loop 2
Level 17
Level 4
Level 1
Level 11
Buffle-BarrelRegion
Guide Tube
(2) Detailed model of in-vessel structures
Include core buffle-barrelregion and reactor control rodguide tubes.
HTSTRs are modeled toconserve their volume andheat transfer area.
Based on the drawings lentfrom the electric company, soinput data are confidential.
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1. Preparation of the input data with Fine noding model
Fig.3 ECCS Injection FlowTable Input
(3) Other reactor coolant systemcomponents
Pressurizer and accumu-latorsare modeled by PIPEcomponents.
ECCS low pressure injec-tionflow is modeled by FILLcomponent. (Fig.3)
This table is applied to eachintact cold legs.
0
50
100
150
0.0 0.2 0.4 0.6 0.8 1.0
pressure (M Pa)mass flow (kg/s/loop)
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1. Preparation of the input data with Fine noding model
Fig.4 CV Pressure Table Input(4) Containment vessel
Containment vessel free volumeis not modeled.
Containment vessel pres-sure ismodeled by BREAK component.(Fig.4)
This table is based on the reactorestablishment permit report.
Pressure increases linearly to0.26 MPa by 15 s
0
0.1
0.2
0.3
0 50 100 150 200 250
tim e (s)
pressure (MPa)
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1. Preparation of the input data with Fine noding model
Fig.5 Core Power Table Input(5) Reactor power
Reactor core power is modeledby time table. (Fig.5)
It is stepped down to 7% ofinitial power.
It includes decay heat of ANS-1979 plus 2 sigma. 0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250
tim e (s)
power ratio
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2. Large break LOCA analysis by Fine noding model
(1) Noding and boundary conditions
Fine noding model and boundary conditions are used
Figure 1 to 5 show these analysis model
Power distribution is defined by Average-power Rod (AVRod)
Hot rod is modeled by Additional Supplemental Rod (ASRod)
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2. Large break LOCA analysis by Fine noding model
(2) Description of Fine noding model
guillotineBreak shape
loop 4 RCP dischargeBreak point
34.7*1.22=42.3, equivalent toFQ=1.31*1.45*1.22=2.32
42.3AS Rod max linear power density(kW/m)
3,411/50,952/3.66*1.31*1.45=0.034734.7AV Rod max linear power density(kW/m)
25 points input based on cosine-shapedistribution
1.45z-direction max power ratio
ring average of cosine-shape distribution1.31r-direction max power ratio
3,411Initial reactor power (MWt)
3*4*8Core sell division (r, t, z)
5*4*17VESSEL cell division (r, t, z)
nhtstr35Number of HTSTRs
ncomp107Number of Components
NoteValueItem
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2. Large break LOCA analysis by Fine noding model
(3) Result of transient analysis
1,074 KPCT 3rd peak appeared99
timer delayed operationECCS injection started39
1,100 KPCT 2nd peak appeared38
judged by the flow direction at core bottomReflood phase started33
set pressure at 4.5 MPaAccumulator injectionstarted
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1,120 KPCT 1st peak appeared4
Assumption, reactor power step down to 7% by 0.1 s,followed by decay heat of ANS(1979)+2 sigma
reactor stop0
Assumption, flow coastdown by Semiscale test facilitypump characteristics
loss of electrical power toRCPs
0
after 1,000 s Null Transientbreak0
noteeventtime (s)
a. Chronology
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2. Large break LOCA analysis by Fine noding model
(3) Result of transient analysisb. Core pressure
0
5
10
15
20
0 50 100 150 200 250
tim e (s)
pressure (MPa)
Fig.6 Core Pressure
Decreases to the CV pressure setas boundary condition about 30s
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2. Large break LOCA analysis by Fine noding model
(3) Result of transient analysisc. Core void fraction
Fig.7 Core Void Fraction
Increases to 1.0 from 0.0instantly after the breakinitiation, and continues athigh value about 0.9
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250
tim e (s)
core center void fraction
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2. Large break LOCA analysis by Fine noding model
(3) Result of transient analysisd. Maximum hot rod surface temperature
Fig.8 M axim um Hot RodSurface TemperatureIncreases to 1,120K from
600K at about 4s.
Reflood phase begins at about33s and the second peak of1,100K appears at 38s.
The third peak of 1,074Kappears at about 99s.
400
600
800
1000
1200
0 50 100 150 200 250
tim e (s)
temperature (K)
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3. Uncertainty Methods Study by Coarse noding model
(1) Trial of GRS type Ordering Statistics
Evaluation parameter is maximum hot rod surfacetemperature during large break LOCA blowdown phase.
Two parameters are selected as cause parameter. (dischargecoefficient CD and power peaking factor Q)
Based on the Wilk’s formula, we can obtain the uppertolerance limit (UTL) at 95% probability on 95% confidencelevel.
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3. Uncertainty Methods Study by Coarse noding model
(2) Noding
This noding model is prepared by US NRC for test problemof US 4-loop PWR.
There are two hot legs and steam-generators.
One of them represents intact loops and is 3-loop-size.
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Fig.9 4-Loop PWR Coarse Noding
3. Uncertainty Methods Study by Coarse noding model
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(25)(20)
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(3)(2)
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Loop 2 (3-loop size)
Loop 1(Broken Loop)
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Fig.10 Reactor Vessel Coarse Noding
3. Uncertainty Methods Study by Coarse noding model
Level 1
Level 7
Level 5
Level 3
Loop 1
(Broken Loop)
Loop 2
Loop 3 Loop 4
Core region is consist of
Three axial noding,
Four azimuthal noding, but
No radius noding.
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3. Uncertainty Methods Study by Coarse noding model
(3) Description of Coarse noding model
150% splitBreak shape
loop 4 RCP dischargeBreak point
27.9 x 1.1=30.7, equivalent toFQ=1.23*1.1=1.35
30.7AS Rod max linear power density (kW/m)
3,250/39,372/3.64 x 1.23=0.027927.9AV Rod max linear power density(kW/m)
4 points input for distribution1.23z-direction max power ratio
3,250Initial reactor power (MWt)
1*4*3Core sell division (r, t, z)
2*4*7VESSEL sell division (r, t, z)
nhtstr15Number of HTSTRs
ncomp48Number of Components
NoteValueItem
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3. Uncertainty Methods Study by Coarse noding model
(4) Cause parameters
0 5 10 15 20 25 30
1.012
1.034
1.056
1.078
1.100
1.122
1.144
1.166
1.188
rank of Q
frequency
0 5 10 15 20 25 30
0.80
0.84
0.88
0.92
0.96
1.00
1.04
1.08
1.12
1.16
1.20
rank of CD
frequency
Power peaking factor Q of 124 random samples : normal distribution, myu=1.1, sigma=0.044
Discharge Coefficient CD of 124 random samples : uniform distribution, min=0.8, max=1.2
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3. Uncertainty Methods Study by Coarse noding model
(5) Typical maximum rod surface temperatureBy different Q=1.0, 1.1, 1.2, and fixed CD=1.0
By different CD=0.8, 1.0, 1.2, and fixed Q=1.1
Maximum value of each curve is “blowdown peak”.
500
600
700
800
900
0 1 2 3 4 5 6
tim e (s)
temperature (K)
Q =1.2Q=1.1
Q=1.0
500
600
700
800
900
0 1 2 3 4 5 6
tim e (s)
temperature (K)
CD =1.2
CD=1.0
CD=0.8
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3. Uncertainty Methods Study by Coarse noding model
(6) Discussion of blowdown peaksBlowdown peaks based on random Q and CD
Both figures are arranged from the same results of 124 cases.
500
600
700
800
900
0.9 1.0 1.1 1.2 1.3
peaking factor Q
temperature (K)
a. Arrangement by QThis distribution showswidely spread and smallpositive correlation.
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3. Uncertainty Methods Study by Coarse noding model
b. Arrangement by CD
This distribution showsobvious positive correlationfocusing to about 830K withabout 50K spread.
500
600
700
800
900
0.6 0.8 1.0 1.2 1.4
discharge coefficient CDtemperature (K)
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3. Uncertainty Methods Study by Coarse noding model
c. 95-95 upper tolerance limit based on Wilk’s formula
These values are equivalent as Upper Tolerance Limit of 95%probability on 95% confidential level based on the Wilk’sformula.
855 K3rd max of 124 samples124856 K2nd max of 93 samples93863 K1st max of 59 samples59
value95%*95% UTLNumber ofsamples
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3. Uncertainty Methods Study by Coarse noding model
(7) Conclusion and future plan
We have made prototype of GRS-type uncertainty evaluationsystem.
We will select several ten pieces of cause parameter,
And modify the TRAC-P code to handle those parameters by“tracin”,
And apply this uncertainty evaluation system to evaluate threepeaks of large break LOCA PCT using fine noding model.