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XT-ADS Transient Analysis M. Schikorr, E. Bubelis EUROTRANS: DM1 WP1.5 : “Safety” Madrid , 13-14 November 2007. Topics:. Design Criteria for XT-ADS 2.XT-ADS design Data for Transient Analysis 3.Some XT-ADS results to the ULOF transient. 1.Some important XT-ADS Design Criteria:. - PowerPoint PPT Presentation
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Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 1
XT-ADS Transient AnalysisXT-ADS Transient Analysis
M. Schikorr, E. BubelisM. Schikorr, E. Bubelis
EUROTRANS: DM1 WP1.5 : “Safety”
Madrid , 13-14 November 2007
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 2
1. Design Criteria for XT-ADS
2. XT-ADS design Data for Transient Analysis
3. Some XT-ADS results to the ULOF transient
Topics:
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 3
1. Neutron Flux sufficiently high ( ~ 2.0E15 n/cm2/s ) to allow XT-ADS to operate as an irradiation facility (i.e. for MA sub-assembly testing).
2. Operate XT-ADS at k_eff ~ 0.95 - 0.97 with several (8?) test rig positions. Design currently optimized by Task Force (Struwe).
3. Design core and primary system in such a manner to allow sufficient natural convection flow rate especially to sustain a ULOF transient for at least 30 minutes without „large number“ of pin failures (i.e. via gas blowdown. Note: this does not mean clad melting !!)
1. Some important XT-ADS Design Criteria:
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 4
Assure a sufficiently large natural convection flow rate ( > 25 % nominal flow) under ULOF conditions.
This implies :
1. keep pressure drop across the core „low“ (~< 0.75 bar) by selecting an appropriate fuel pin / subassembly design
2. minimize pressure losses throughout the primary / DHR system such that total system pressure loss <~ 1.0 – 1.1
bar
3. assure a height differential between the core midplane and the heat sink midplane of at least ~ 2.00 m
XT-ADS ULOF Design Criteria requires :
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 5
1. Select an appropriate pin / sub-assembly design by optimizing the pin diameter, pin pitch, wrapper dimensions etc.
2. Minimize the number of grid-spacers and optimise design (reduce grid spacer thickness to a minimum: 0.25 mm from currently 0.50 mm)
3. Keep the length of the fuel pin low
4. Optimize inlet and outlet support structures to keep pressure drops small
Keeping P_core in the XT-ADS Design low:
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 6
Most current XT-ADS Design Data: 580mm Lower Gas Plenum
Thermal power 56.85 MW
Average Linear Power 146.1 W/cm
Axial Form Factor f_ax 1.257Radial Form Factor f_rad_hot_SA 1.312
f_peak_pin 1.048f_rad_tot 1.375f_tot_hot_SA 1.649f_tot_peak_pin 1.728
580
Fuel Bundle and Pin Design
Dimensions UnitsNumber of pins 91Number of anchoring SS pins per SA 1Active Fuel Heights 60.0 cmPitch to Diameter Ratio 1.410Pin diameter 6.55 mmPitch 9.24 mmAnnulus diameter 1.6 mmNumber of Pin rows in SA 5Clad Thickness 0.475 mmCold Gap between clad and fuel 0.100 mmPellet diameter 5.400 mmAvailable inter-pin gap for spacers 3.8 mmSpace pin - inner wrapper 1.3350 mmWidth over inner flats 89.20 mmThickness Wrapper 2.00 mmGap between SA´s 3.00 mmWidth over outer flats (wrapper) 93.20 mmWidth over unit cell (includes Sgap) 96.20 mm
Number Fuel Subassemblies 72Number of SA spallation zone 3Number Grid Spacers 3
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 7
Peak Burn Up 100 MWd/kgiHM
For MOX Fuel use Philipponneau Correlation for thermal conductivity
BOC EOCO/M 1.975 2Porosity 5% 7.50%
580
Other XT-ADS Data Inputs:
580mm Lower Gas Plenum
Heights difference core / heat sink 2.00 m
T_in 300 °CT_out 400 °CFlow Rate 3854 kg/s
Current Grid Spacer Design :
Proposed Grid Spacer Design:
Calc. Prim. System Pressure Drops: 4 Spacers @ 0.50mm thickness 0.604 barCore Inlet/Outlet 0.117 barFlow Friction 0.413 barTotal Core 1.134 barTotal Prim. System 1.564 bar
Assumed Zeta Factor (Ratio of Prim.System/Core Pressure Drop)
1.38
Calc. Prim. System Pressure Drops: 4 Spacers @ 0.25mm thickness 0.178 barCore Inlet/Outlet 0.117 barFlow Friction 0.413 barTotal Core 0.708 barTotal Prim. System 0.977 barAssumed Zeta Factor (Ratio of Prim.System/Core Pressure Drop)
1.38
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 8
XT-ADS Nominal Conditions at BOC :
BOC Axial Temperature Profile Average Pin, 146 W/cm and no oxide layer
383.6
350400
419
1025
823
928
621668
1189
300
400
500
600
700
800
900
1000
1100
1200
1300
-30 -20 -10 0 10 20 30Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding
Coolant
Center Fuel
Surf Fuel
Avg Fuel
BOC Axial Temperature Profile Peak Pin, 201 W/cm and no oxide layer
414.6
369438
463
1263
9731098
684 731
1470
300
500
700
900
1100
1300
1500
1700
-30 -20 -10 0 10 20 30Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Note: using Ushakov (Zhukov-bundle) instead of Subbotin will reduce clad temps by about 9 °C
XT-ADS :
Pin = 6.55mm OD
T_in = 300 °C
4 Grid Spacers @ 0.50 mm
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 9
XT-ADS Nominal Conditions at EOC :
Oxide Layer = 30 um
At 1 [W/m/K] oxide layer thermal conductivity
EOL Axial Temperature Profile, Avg Pin 146 W/cm and 30 um Oxide Layer
405
350400
438
918
753
866
588648
1084
300
400
500
600
700
800
900
1000
1100
1200
-30 -20 -10 0 10 20 30Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding surf
Coolant
Center Fuel
Surf Fuel
Avg Fuel
EOL Axial Temperature Profile, Peak Pin 201 W/cm and 30 um Oxide Layer
444
369438
489
1175
928
1081
680756
1408
300
500
700
900
1100
1300
1500
-30 -20 -10 0 10 20 30Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding surf
Coolant
Center Fuel
Surf Fuel
Avg Fuel
XT-ADS :
Pin = 6.55mm OD
T_in = 300 °C
4 Grid Spacers @ 0.50 mm
At EOC (~ 100 MWd/kg peak burnup):
Fission Gas Pressure in peak pin ~ 38.4 bar
Degraded thermal fuel conductivity (Philiponneau)
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 10
XT-ADS :
Pin = 6.55mm OD
T_in = 300 °C
No Oxide Layer
XT-ADS ULOF-ss
at BOC :
BOC ULOFss Temperature Avg Pin, 146 W/cm and no oxide layer
571.8
520
744
767
1191
980
1118
768
890
1378
300
500
700
900
1100
1300
1500
-30 -20 -10 0 10 20 30Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Clad Failure Time ~ 240 hrs
BOC ULOFss Temperature Peak Pin, 201 W/cm and no oxide layer
638.4
572
848
878
1450
1152
1315
8541007
1677
300
500
700
900
1100
1300
1500
1700
1900
-30 -20 -10 0 10 20 30Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Clad Failure Time ~ 0.5 hrs4 Grid Spacers @ 0.50mm thickness
H (core-HX) = 2.0 m
P_primsystem = 1.56 bar
Conclusion:
At BOC ULOFss Clad Failure Time of ~ 0.5 hrs for Peak Pin is acceptable !!
Current Spacer design:
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 11
XT-ADS ULOF-ss
at EOC :
EOL ULOFss Temperatures , Peak Pin 194 W/cm and 30 um Oxide Layer
660
566
837
881
1366
1111
1300
857
1009
1618
300
500
700
900
1100
1300
1500
1700
-30 -20 -10 0 10 20 30
Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding surf
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Clad Failure Time ~ 0.13 hrs
EOL ULOFss Temperatures , Avg Pin 146 W/cm and 30 um Oxide Layer
593
520
744
778
1113
932
1087
751
880
1314
300
500
700
900
1100
1300
1500
-30 -20 -10 0 10 20 30
Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding surf
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Clad Failure Time ~ 33 hrs
XT-ADS :
Pin = 6.55mm OD
T_in = 300 °C
Oxide Layer = 30 um
4 Grid Spacers @ 0.50mm thickness
H (core-HX) = 2.0 m
P_primsystem = 1.56 bar
Conclusion:
At EOC ULOFss Clad Failure Time of ~ 0.13 hrs for Peak Pin is somewhat less than the 0.5 hrs design goal!!
Current Spacer design:
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 12
XT-ADS :
Pin = 6.55mm OD
T_in = 300 °C
No Oxide Layer
XT-ADS ULOF-ss
at BOC :
4 Grid Spacers @ 0.25mm thickness
H (core-HX) = 2.0 m
P_primsystem = 0.977 bar
Conclusion:
At BOC ULOFss Clad Failure Time of ~ 45 hrs for Peak Pin
BOC ULOFss Temperature Avg Pin, 146 W/cm and no oxide layer
537.3
487
676
699
1161
951
1079
740840
1341
300
500
700
900
1100
1300
1500
-30 -20 -10 0 10 20 30Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Clad Failure Time ~ 19 000 hrs
BOC ULOFss Temperature Peak Pin, 201 W/cm and no oxide layer
595.5
530
763
793
1415
11171268
820943
1635
300
500
700
900
1100
1300
1500
1700
1900
-30 -20 -10 0 10 20 30Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Clad Failure Time ~ 45 hrs
Proposed Spacer design:
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 13
XT-ADS ULOF-ss
at EOC :XT-ADS :
Pin = 6.55mm OD
T_in = 300 °C
Oxide Layer = 30 um
4 Grid Spacers @ 0.25mm thickness
H (core-HX) = 2.0 m
P_primsystem = 0.977 bar
Conclusion:
At EOC ULOFss Clad Failure Time of ~ 9 hrs for Peak Pin is now ok !!
EOL ULOFss Temperatures , Avg Pin 146 W/cm and 30 um Oxide Layer
558
487
676
711
1077
899
1042
721829
1270
300
500
700
900
1100
1300
1500
-30 -20 -10 0 10 20 30
Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding surf
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Clad Failure Time ~ 2200 hrs
EOL ULOFss Temperatures , Peak Pin 194 W/cm and 30 um Oxide Layer
618
525
754
798
1325
1073
1249
821948
1570
300
500
700
900
1100
1300
1500
1700
-30 -20 -10 0 10 20 30
Axial Core Position [cm]
Te
mp
era
ture
s [
°C]
Cladding surf
Coolant
Center Fuel
Surf Fuel
Avg Fuel
Clad Failure Time ~ 9 hrs
Proposed Spacer design:
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 14
XT-ADS Transient : ULOF
Assumptions:
1. Pump Coast down charactersitics taken from Myhrra Report (Draft 2) using a pump rundown halftime = 3.8 sec
2. Assume a similiar flow transition characterisitics from pump coast down to natural convection as has been assumed for the PDS-XADS design
Source: Myhrra Report – Draft 2 June 2005
~3.8 sec
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 15
Flow transition characterisitics from pump coast down to natural convection under ULOF conditions as has been assumed for the PDS-XADS design
ULOF Transient for 80 MW LBE-cooled XADS and XT-ADS using similiar flow transition dynamics
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
1.10
0 10 20 30 40 50 60 70 80 90 100
Time [sec]
rel.
Ma
ss
Flo
w R
ate
[fr
]
XT-ADS ULOF ( SIM-ADS )
Flow_RELAP ( XADS: ANSALDO )
PDS-XADS ULOF Flow Dynamics
XT-ADS ULOF Flow using PDS-XADS transition characterics
w_nat = 25.4 % nominal for avg pin
w_nat ~ 48 % for XADS
undershoot to 28 %
undershoot to 13.5 %
I believe that this XADS transition flow characterisitcs was experimentally valided in Italy (Brasemone) and RELAP was validated using this data
TALL experimental data (LBE-loop, KTH)
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 16
Benchmarking TRAC and SIM-ADS to TALL Natural Convection Transient
TALL Natural Convection Transient Experimental data (LBE-loop, KTH)
Temperatures
200
250
300
350
400
450
500
0 200 400 600 800 1000 1200 1400 1600 1800 2000Time [sec]
Tem
per
atu
re [
°C]
Cool_out SIM-ADS
Cool_in SIM-ADS
T_in TALL exp. - 1
T_out TALL - exper
T_in HX TALL exp
T_out HX TALL -expT_in TALL exp. - 2
T_in TALL exp. -3
T_out PSI TRACE
T_in PSI TRACE
Coolant
Flow Rate
0.00.10.20.30.40.50.60.70.80.91.01.1
0 200 400 600 800 1000 1200 1400 1600 1800 2000Time [sec]
rel.
Un
its
[fr]
Flow_Cool SIM-ADS
TALL -exp. data
PSI TRACE calculation
grad ~ 1/100
Source : W. Ma (KTH),et.al., E. Bubelis, P. Coddington (PSI) „TALL Experiments …..“ NED Reference to be completed
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 17
XT-ADS ULOF Transient Cases Analysed:
1. ULOF: BOC, Peak Pin, 4 Spacer @ 0.50mm thickness
2. ULOF: EOC, Peak Pin, 4 Spacer @ 0.50mm thickness, 30 um oxide
3. ULOF: BOC, Peak Pin, 4 Spacer @ 0.25mm thickness
4. ULOF: EOC, Peak Pin, 4 Spacer @ 0.25mm thickness , 30 um oxide
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 18
Case 1 : ULOF, BOC, Peak Pin, 4 Spacer @ 0.50mm thickness, no oxide
Conclusion:
For current design XT-ADS peak pin clad will fail 32 sec into the ULOF transient already under BOC conditions because of flow undershoot < 20 % nom. flow at 36 sec into transient even though the ULOF-ss limit of 30 min is attained after 60 sec into ULOF.
ULOF FzK (SIM-ADS) : Power and Flow Rate
0.00.10.20.30.40.50.60.70.80.91.01.1
0 20 40 60 80 100Time [sec]
rel.
Un
its
[fr
]
Power_th
Flow_Cool
Power
Flow
ULOF FzK (SIM-ADS) : Temperatures
300
500
700
900
1100
1300
1500
1700
1900
2100
0 20 40 60 80 100Time [sec]
Te
mp
era
ture
[°C
] Fuel_c_peak
Clad_peak
Cool_out
Cool_in
Fuel
T_clad_max = 1100 °C
Coolant
Cladding
ULOF FzK (SIM-ADS) : Clad Failure and Fission Gas Pressure
1.E+00
1.E+02
1.E+04
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
1.E+16
1.E+18
0 20 40 60 80 100Time [sec]
Cla
d F
ailu
re T
ime
[s
ec
]
2.2
2.2
2.3
2.3
2.4
2.4
2.5
2.5
2.6
Fis
sio
n G
as
Pre
ss
ure
[b
ar]
Clad Failure Time [sec]
Fission Gas Pressure [bar]
30 min
Min Clad Failure Time < 1 sec
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 19
Case 2 : ULOF, EOC, Peak Pin, 4 Spacer @ 0.50mm thickness, 30 um oxide
Conclusion:
For current design XT-ADS peak pin clad will fail 32 sec into the ULOF transient under EOC conditions because of flow undershoot < 20 % nom. flow at 36 sec even though the ULOF-ss limit of ~20 min is attained after 60 sec into ULOF.
ULOF FzK (SIM-ADS) : Power and Flow Rate
0.0
0.1
0.20.3
0.4
0.5
0.6
0.7
0.80.9
1.0
1.1
0 20 40 60 80 100Time [sec]
rel.
Un
its
[fr
]
Power_th
Flow_Cool
Power
Flow
ULOF FzK (SIM-ADS) : Temperatures
300
500
700
900
1100
1300
1500
1700
1900
0 20 40 60 80 100Time [sec]
Te
mp
era
ture
[°C
]
Fuel_c_peak
Clad_peak
Cool_out
Cool_in
Fuel
T_clad_max = 1100 °C
Coolant
Cladding
ULOF FzK (SIM-ADS) : Clad Failure and Fission Gas Pressure
1.E+00
1.E+02
1.E+04
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
1.E+16
0 20 40 60 80 100Time [sec]
Cla
d F
ailu
re T
ime
[se
c]
36
37
38
39
40
41
42
43
Fis
sio
n G
as
Pre
ss
ure
[b
ar]
Clad Failure Time [sec]
Fission Gas Pressure [bar]
30 min
Min Clad Failure Time < 1 sec
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 20
Case 3 : ULOF, BOC, Peak Pin, 4 Spacer @ 0.25mm thickness, no oxide
Conclusion:
For 0.25cm Spacer design XT-ADS clad will most likely survive without clad failure under BOC conditions even though clad failure time dropped down to ~ 80 sec about 36 sec into ULOF transient. Flow undershoot will recover sufficiently fast.
ULOF FzK (SIM-ADS) : Power and Flow Rate
0.00.1
0.20.30.4
0.50.6
0.70.80.9
1.01.1
0 20 40 60 80 100Time [sec]
rel.
Un
its
[fr
]
Power_th
Flow_CoolPower
Flow
ULOF FzK (SIM-ADS) : Temperatures
300
500
700
900
1100
1300
1500
1700
1900
0 20 40 60 80 100Time [sec]
Te
mp
era
ture
[°C
] Fuel_c_peak
Clad_peak
Cool_out
Cool_in
Fuel
T_clad_max = 990 °C
Coolant
Cladding
ULOF FzK (SIM-ADS) : Clad Failure and Fission Gas Pressure
1.E+00
1.E+02
1.E+04
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
1.E+16
1.E+18
0 20 40 60 80 100Time [sec]
Cla
d F
ailu
re T
ime
[s
ec
]
2.2
2.2
2.3
2.3
2.4
2.4
2.5
2.5
Fis
sio
n G
as
Pre
ss
ure
[b
ar]
Clad Failure Time [sec]
Fission Gas Pressure [bar]
30 min
Min Clad Failure Time ~ 80 sec
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 21
Case 4 : ULOF, EOC, Peak Pin, 4 Spacer @ 0.25mm thickness, 30 um oxide
Conclusion:
For 0.25cm Spacer design XT-ADS peak pin clad will however most likely fail under EOC conditions because clad failure time dropped down to ~ 0 sec about 36 sec into ULOF transient. Avg Pin clad will survive – see next figure.
ULOF FzK (SIM-ADS) : Power and Flow Rate
0.00.10.20.30.40.50.60.70.80.91.01.1
0 20 40 60 80 100Time [sec]
rel.
Un
its
[fr
]
Power_th
Flow_Cool
Power
Flow
ULOF FzK (SIM-ADS) : Temperatures
300
500
700
900
1100
1300
1500
1700
1900
0 20 40 60 80 100Time [sec]
Te
mp
era
ture
[°C
]
Fuel_c_peak
Clad_peak
Cool_out
Cool_in
Fuel
T_clad_max ~ 1020 °C
Coolant
Cladding
ULOF FzK (SIM-ADS) : Clad Failure and Fission Gas Pressure
1.E+00
1.E+02
1.E+04
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
1.E+16
0 20 40 60 80 100Time [sec]
Cla
d F
ailu
re T
ime
[s
ec
]
37
38
39
40
41
42
43
Fis
sio
n G
as
Pre
ss
ure
[b
ar]
Clad Failure Time [sec]
Fission Gas Pressure [bar]
30 min
Min Clad Failure Time ~ 0 sec
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 22
Case 4 : ULOF, EOC, Avg Pin, 4 Spacer @ 0.25mm thickness, 30 um oxide
Conclusion:
For 0.25cm Spacer design XT-ADS avg pin clad will not fail under EOC conditions because clad failure time dropped down to only 800 sec about 36 sec into ULOF transient and thereafter recovers to several hours.
ULOF FzK (SIM-ADS) : Power and Flow Rate
0.00.10.20.30.40.50.60.70.80.91.01.1
0 20 40 60 80 100Time [sec]
rel.
Un
its
[fr
]
Power_th
Flow_Cool
Power
Flow
ULOF FzK (SIM-ADS) : Clad Failure and Fission Gas Pressure
1.E+00
1.E+02
1.E+04
1.E+06
1.E+08
1.E+10
1.E+12
1.E+14
1.E+16
1.E+18
0 20 40 60 80 100Time [sec]
Cla
d F
ailu
re T
ime
[s
ec
]
27
28
28
29
29
30
30
31
Fis
sio
n G
as
Pre
ss
ure
[b
ar]
Clad Failure Time [sec]
Fission Gas Pressure [bar]
30 min
Min Clad Failure Time ~800 sec
ULOF FzK (SIM-ADS) : Temperatures
300
500
700
900
1100
1300
1500
0 20 40 60 80 100Time [sec]
Te
mp
era
ture
[°C
]
Fuel_c_peak
Clad_peak
Cool_out
Cool_in
Fuel
T_clad_max ~ 880 °C
Coolant
Cladding
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 23
Current Conclusions on XT-ADS ULOF Transient (1/2) :
1.) This transient is very sensitive to natural convection flow rate conditions and thus all plant and design parameters that influence this parameter. During the transient clad failure times can decrease to a few 10 seconds depending on the transitional flow dynamics (natural convection flow undershoot).
2.) The ULOF-ss (steady state) clad design limit condition of at least 30 min survival time are difficult to abide by under ULOF transient conditions for the current design even if the spacer design of 0.25mm thickness is adopted. Additional design measures are needed such as either decrease in primary system pressure drop or by increasing the elevation of the HX relative to the core above the current 2.0 m differential, or by other means (what are those ?).
Forschungszentrum KarlsruheTechnik und Umwelt
IRS /FzK W.M.SchikorrEUROTRANS WP1.5 Safety Meeting : Madrid, Nov 13-14. 2007 24
Current Conclusions on XT-ADS ULOF Transient (2/2) :
3.) The XT-ADS core and primary system designs are currently still a moving target. The most recent design iteration proposal calls for a reduced secondary side pressure to 16 bar allowing for power level dependant core inlet temperature variations between 300°C and 200°C.
This calls for a revised MHX modelling (2 phase flow as saturation temperature of 16 bar is 200°C).
This implies that under norminal conditions – 300°C core inlet, the secondary side HX is mostly in the vapor state. Who has a 2 phase MHX model going and running stable at all plant conditions ???