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Development of a Development of a 3D Neutron Kinetic3D Neutron Kinetic--ThermalThermal--hydraulic hydraulic
Balance between feed water and steam mass flow rate
% 0.0 0.7%
?
485 20 Average graphite
temperature oC ?
484 ?
Steady Statedemonstration:
20 selected parameters
-300.0 -250.0 -200.0 -150.0 -100.0 -50.0 0Time (s)
265.0
270.0
275.0
280.0
285.0
290.0
295.0
300.0
305.0
Tem
pera
ture
(°C
)
XXX LOP17b tempf145260000X
X
XX
X XX X X X X X X X X X X X X
YYY LOP17b tempf214260000
Y
Y Y YY
YY Y Y Y Y Y Y Y Y Y Y Y Y
ZZZ LOP17b tempf145470000Z
ZZ Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z
VVV LOP17b tempf214470000V
V V V V V V V V V V V V V V V V V
-300.0 -250.0 -200.0 -150.0 -100.0 -50.0 0Time (s)
5000
5050
5100
5150
5200
5250
5300
5350
Mas
s Fl
ow ra
te (K
g/s)
XXX V8=V5+V6+V7
X
X
X
X
X
XX X X X X X X X X X X X
Qualification Process Qualification Process -- SS levelSS level
SD pressure
Core flow rateright side
Core inlet-outlet tempright side
AA flow rateright side
-350.0 -300.0 -250.0 -200.0 -150.0 -100.0 -50.0 0Time (s)
6.75
6.80
6.85
6.90
6.95
7.00
7.05
Pres
sure
(MPa
)
XXX LOP17b p360010000X
X
XX
XX X X X X X X X X X X X
YYY LOP17b p410010000
Y
YY
YY Y Y Y Y Y Y Y Y Y Y Y Y
ZZZ LOP17b p860010000
Z
Z
ZZ
ZZ Z Z Z Z Z Z Z Z Z Z Z Z
VVV LOP17b p910010000
V
VV
VV V V V V V V V V V V V V
-300.0 -250.0 -200.0 -150.0 -100.0 -50.0 0Time (s)
96.0
98.0
100.0
102.0
104.0
106.0
108.0
110.0
112.0
Mas
s Fl
ow R
ate
(Kg/
s)
XXX LOP17b mflowj142200000
X
X X XX X X X X X X X X X X X X X
-300.0 -250.0 -200.0 -150.0 -100.0 -50.0 0Time (s)
80.0
85.0
90.0
95.0
100.0
105.0
110.0
Volu
me
(m^3
)
XXX LOP17b cntrlvar401
X
XX
XX
X X X X X X X X X X X X X
YYY LOP17b cntrlvar403
Y
YY
YY
Y Y Y Y Y Y Y Y Y Y Y Y Y
ZZZ LOP17b cntrlvar405
Z
Z ZZ
ZZ Z Z Z Z Z Z Z Z Z Z Z Z Z
VVV LOP17b cntrlvar407
VV
V VV
V V V V V V V V V V V V V
-300.0 -250.0 -200.0 -150.0 -100.0 -50.0 0Time (s)
250
300
350
400
450
500
550
600
650
Tem
pera
ture
(°C
) XXX LOP17b httemp145401301
X X X X X X X X X X X X X X X X X X X
YYY LOP17b httemp145401302
Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
ZZZ LOP17b httemp145401303
Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z Z
VVV LOP17b httemp145401304
V V V V V V V V V V V V V V V V V VJJJ LOP17b httemp145401305
J J J J J J J J J J J J J J J J J J
HHH LOP17b httemp145401306
H H H H H H H H H H H H H H H H H
### LOP17b httemp145401307
# # # # # # # # # # # # # # # # #
OOO LOP17b httemp145401308
O O O O O O O O O O O O O O O O O
AAA LOP17b httemp145401309
A A A A A A A A A A A A A A A A
BBB LOP17b httemp145401310
B B B B B B B B B B B B B B B B
CCC LOP17b httemp145401311
C C C C C C C C C C C C C C C
DDD LOP17b httemp145401312
D D D D D D D D D D D D D D D
Qualification Process Qualification Process -- SS levelSS level
Graphite radial tempdistribution
13th plane
SD volume
Clad Temp. axial distribution
-300.0 -250.0 -200.0 -150.0 -100.0 -50.0 0Time (s)
270.0
275.0
280.0
285.0
290.0
295.0
300.0
305.0
310.0
315.0
Tem
pera
ture
(°C
)
XXX LOP17b httemp214500212
X
XX
XX X
X X X X X X X X X X X X X
YYY LOP17b httemp214500312
Y
Y Y YY
YY Y Y Y Y Y Y Y Y Y Y Y Y
ZZZ LOP17b httemp214500412
Z
Z Z Z ZZ Z Z Z Z Z Z Z Z Z Z Z Z Z
VVV LOP17b httemp214500512
V V VV V
V V V V V V V V V V V V V
JJJ LOP17b httemp214500612
J J J JJ J J J J J J J J J J J J J
HHH LOP17b httemp214500712H H H H H H H H H H H H H H H H H### LOP17b httemp214500812# # # # # # # # # # # # # # # # #OOO LOP17b httemp214500912
O O O O O O O O O O O O O O O O O
AAA LOP17b httemp214501012
A A A A A A A A A A A A A A A A
BBB LOP17b httemp214501112
B B B B B B B B B B B B B B B B
CCC LOP17b httemp214501312
C C C C C C C C C C C C C C C
DDD LOP17b httemp214501412
D D D D D D D D D D D D D D D
EEE LOP17b httemp214501512
E E E E E E E E E E E E E E
FFF LOP17b httemp214501612
F F F F F F F F F F F F F F
GGG LOP17b httemp214501712
G G G G G G G G G G G G G
III LOP17b httemp214501812
I I I I I I I I I I I I I
LLL LOP17b httemp214501912
L L L L L L L L L L L L
MMM LOP17b httemp214502012
M M M M M M M M M M M M
Qualification ProcessQualification Process
On Transient levelREPLICATION OF A SELECTED TEST
Accuracy quantificationQualitative evaluation
LOSS of POWERComparisonwith exp. data
FFT BM
Comparison with Russian results
Qualification Process Qualification Process –– On TransientOn TransientTime sequence of main events
UnipiUnipiTime (s)Time (s)
EventEvent RussianRussianTime (s)Time (s)
0.0. Loss of preferred AC power supply. Diesel generators start.Loss of preferred AC power supply. Diesel generators start. 0.0.
0.40.4
1.01.0
1.01.0
1.01.0
226.226.
15.015.0
55.055.0
180.0180.0
600.600.
1211.1211.
3000.3000.
0.40.4 Turbine isolation and regulation valves fully closed.Turbine isolation and regulation valves fully closed.
1.01.0 11stst AZAZ--5 command issued by CPS upon EPPS reading that turbine valve has5 command issued by CPS upon EPPS reading that turbine valve has closed. closed. This signal isThis signal is neglected in the simulation.neglected in the simulation.
1.01.0 22ndnd AZAZ--5 command issued as a result of pressure downstream turbine valv5 command issued as a result of pressure downstream turbine valve falling e falling to 12 bar. This signal isto 12 bar. This signal is credited in the simulation. Pcredited in the simulation. Power begins to reduce. CPS rods ower begins to reduce. CPS rods start moving.start moving.
1.01.0 BRUBRU--K valves start to open due to overK valves start to open due to over--pressure. BRUpressure. BRU--K operate as pressure K operate as pressure controller with opening and closure setcontroller with opening and closure set--points equal to 7.11 MPa and 6.86 MPa points equal to 7.11 MPa and 6.86 MPa respectively respectively
3.03.0 First group of MSV start to open.First group of MSV start to open.
Qualification Process Qualification Process –– On TransientOn Transient
0
1000
2000
3000
4000
5000
6000
-500 0 500 1000 1500 2000 2500 3000
Time (s)
Mas
s Fl
ow ra
te (K
g/s)
Total flow rate RU Total flow rate Unipi
Core Mass flow rate vs. time
Considerations on TH modelConsiderations on TH model
• The pioneering study (for UNIPI) of the RBMK reactor type gave the following results:
•Steady State level: all the limits regarding the geometrical fidelity have been fulfilled; precision of few parameters should be improved (i.e. SD mass inventory)•On transient level: a qualitative comparison between Russian and UNIPI results shows some discrepancies (e.g. MSV timing)
• The same phenomena are predicted from both calculations (SD pressure trend)
• Lacking of measured values does not permit the application of the FFT-BM to quantify the accuracy of the obtained results
• The nodalisation is capable to reproduce the selected transient –LOOP – even though some improvements are necessary
Successive stepSuccessive step development of 3D NK model
RBMK 3D NK PeculiaritiesRBMK 3D NK Peculiarities•• RBMK peculiaritiesRBMK peculiarities::
Loosely coupled coreLoosely coupled coreLargeLarge number of nodes (30000)number of nodes (30000)24882488 channels (channels (15701570 FC, FC, 314314 nonnon--FC FC (AA, Axial detectors,..), and (AA, Axial detectors,..), and 604604Reflector ChannelsReflector Channels))Complex neutron Complex neutron XSecsXSecs structure structure (graphite & fuel temp, water density, (graphite & fuel temp, water density, Xenon Xenon concconc,.. feedbacks),.. feedbacks)Different CR arrangements & type:Different CR arrangements & type:
Up & Bottom InsertedUp & Bottom InsertedManual CR, Shortened CR, Fast Manual CR, Shortened CR, Fast Acting Scram CRActing Scram CR
1D1D-- 2D neutron2D neutron--gamma gamma transport code for transport code for lattice lattice burnupburnupcomplete geometric flexibilitycomplete geometric flexibilityGenerate FewGenerate Few--Groups Groups Macroscopic Macroscopic XSecsXSecs LibrariesLibraries
•• Database function of:Database function of:ExposureExposureFuel temperatureFuel temperatureGraphite temperatureGraphite temperatureCoolant densityCoolant density
•• 675 675 Compositions Compositions for fuel cells: for fuel cells: 610610for nonfor non--fuel cells: fuel cells: 6565
• Operational data obtained with radial & axial in-core detectors • Reactor core divided axially into 10 layers with a height of 70.0 cm• Upper and lower axial reflectors have a thickness of 30 cm• All non-fuel cell type considered• Validation of the Neutron Cross Sections DatabaseNeutron Cross Sections Database by precise Monte CarloMonte Carlo calculationscalculations
• Bottom, Top and Radial Graphite Reflector Modelled
NESTLE 3D NK modelNESTLE 3D NK model
•• Radial power peaking factor Radial power peaking factor –– 1.621.62•• Radial power distribution: RMS from 130 radial detectors Radial power distribution: RMS from 130 radial detectors –– 7%7%•• Axial power distribution: RMS from 12 axial detectors Axial power distribution: RMS from 12 axial detectors –– 8%8%
•• Several Plant transients were proposed and analyzed in order Several Plant transients were proposed and analyzed in order to check the codes capabilities in modeling RBMK phenomena:to check the codes capabilities in modeling RBMK phenomena:
CR Withdrawal CR Withdrawal **CR Bank Withdrawal CR Bank Withdrawal **GDH RuptureGDH RuptureFlow Blockage in GDH Flow Blockage in GDH **Flow Blockage in FC Flow Blockage in FC **CPS cooling LOCA CPS cooling LOCA
* * = sample results given in next slides= sample results given in next slides