FER MELCOR Activities FER MELCOR Activities
Presenter: Davor Grgić
Vesna Benčik, Davor Grgić, Siniša Šadek, Štefica Vlahović
Faculty of Electrical Engineering and Computing (FER)
University of Zagreb, Croatia
• Development of NPP Krško input deck for MELCOR 1.8.6 and MELCOR 2.2 code
• Validation of NEK MELCOR 1.8.6 and MELCOR 2.2 input deck
• Modelling of Engineering Safety Features available for non-severe accident conditions and planned
mitigation actions
• Verification of MELCOR input deck by comparison of non-severe accident sequences with RELAP5/MOD 3.3 code.
• Equipment survivability use
FER MELCOR Activities
Content:
• NPP Krško nodalization for MELCOR 1.8.6 and MELCOR 2.2
• Verification of MELCOR input deck by comparison of 3 inch cold leg LOCA with RELAP5/MOD 3.3 code
• MELCOR 1.8.6 and MELCOR 2.2 analysis of SBO.
• Verification of containment model with Gothic
• Source term preparation
• Different ES applications
MELCOR nodalization scheme for NPP Krško
CV006 CV080 CV081 CV082 CV083 CV085
CV001
CV084 CV086
CV087
FL001 CV002
CV004 CV005 FL002
FL003 FL004
FL005
FL147 FL148
FL149 FL155 FL154
FL152 FL153
FL150 FL151
FL006 FL018
FL144 FL145
CV003 CV090
FL160
CV079
CV067 CV068 CV069 CV070 CV071 CV072 CV073 CV074 CV075 CV076 CV077 CV078
CV007 CV008 CV009 CV010 CV011 CV012 CV013 CV014 CV015 CV016 CV017 CV018
CV101 CV102
FL111 CV 105 CV103
FL102 FL301 FL302
CV301 CV302 CV303
FL304
FL303
CV304 CV305
FL307 FL306
CV308 CV307 CV306 FL305
FL106
FL107 CV 106
CV107 FL108 CV 108
RCP 1 FL164 CV110
FL 199 CV104
FL113 FL114
FL115 LOW COMP (CV702)
FL351
CV351 CV352 FL352
CV342
FL342 CV356
FL354
RPV
FL201 SG 1
CV201 CV202
FL202 FL401 FL402
CV401 CV402 CV403
FL407 FL406
CV408 CV407 CV406
FL206
FL207 CV 206
CV207 FL208
CV 208 RCP 2 FL264
CV210
FL 299 FL451
CV451 CV452
CV442
FL442 CV456
SG 2
PRZ
FL357
FL100 FL200
FL166 FL266
CV811 CV921
FL375 FL376 FL377 FL378 FL379 FL380
FL457
CV812 CV922
FL475 FL476 FL477 FL478 FL479 FL480
CV813 CV901
FL814
FL813
FL811 FL812
AFW 2
FL112
PRZ surge line
CV 105
FL736
RWST CV706
FL121 FL122
CV161 CV162
SG1C (CV708) FL157 CV706
FL716
ACC 1
CV 109 CV712 FL746 CV112
FL101
SG2C (CV709) FL257
ACC 2
CV 209
CV712 FL747FL726
CV212
FL265 FL165
FL748
CV712
Containment sump CV814
FL403 FL405
FL452
FL404 CV404
CV405 CV453 CV455
CV454 FL537
CV443
FL455 FL458
FL456
FL453 FL443
FL454
CV353 FL353
FL343 FL358
CV355
CV354 FL355
CV343
FL356
FL517
CV513
MFW 2
FL507
CV503
MFW 1
FL527
AFW 1
CV504 CV514
FL143
FL131
CV702 FL198
NEK containment nodalization The core and lower
plenum in COR package
NPP Krško 3 inch Cold Break LOCA Calculation using RELAP5/MOD 3.3
and MELCOR 1.8.6 Codes
Transient Description and Boundary Conditions
• Postulated accident is a 3 inch Loss of Coolant Accident (LOCA) in cold leg 1 (loop with pressurizer).
• Reactor trip from 100% power is actuated on low pressurizer pressure or high containment pressure signal.
• Trip of both RC pumps is actuated on reactor trip.
• Closure of main steam isolation valves and isolation of main feedwater are initiated on reactor trip.
• Emergency core cooling system is available (5 seconds delay for safety injection).
• Auxiliary feedwater system is available (60 seconds delay)
• Containment fan coolers and containment spray are available
in MELCOR.
Parameters of RELAP5/mod 3.3 nodalization
8
PARAMETER VALUE
1. NUMBER OF NODES
- primary side 300
- secondary side 206
- total 506
2. NUMBER OF JUNCTIONS
- primary side 313
- secondary side 230
- total 543
3. NUMBER OF HEAT STRUCTURES
- primary side 245
- secondary side 138
- total 383
4. OVERALL NUMBER OF MESH POINTS 2127 5. NUMBER OF CORE ACTIVE
STRUCTURES
12 6. HEAT TRANSFER AREA (m2)
- core region 3103.9
- steam generator U-tubes 7343.0
7. NUMBER OF MESH POINTS
- core slabs 16
- steam generator slabs 10
8. NUMBER OF CONTROL VARIABLES 732
9. NUMBER OF TRIPS
- variable 197
- logical 221
- total 418
10. OVERALL PRIMARY SIDE VOLUME (m3)
195.3
Parameters of MELCOR 1.8.6 nodalization
PARAMETER VALUE
1. NUMBER OF VOLUMES
- primary side 69
- secondary side 30
- containment 24
- total 123
2. NUMBER OF FLOW PATHS
- primary side 93
- secondary side 38
- containment 43
- total 174
3. NUMBER OF HEAT STRUCTURES
- reactor vessel 34
- primary side and SG U-tubes 46
- containment 20
- total 100
4. OVERALL NUMBER OF MESH POINTS 731 5. NUMBER OF CORE ACTIVE
STRUCTURES
27 6. NUMBER OF MESH POINTS IN SG
HEAT SLABS
12 7. NUMBER OF CONTROL FUNCTIONS
- real valued 189
- logical 91
- total 280
7. NUMBER OF TABULAR FUNCTIONS 47
RELAP5/mod 3.3 nodalization scheme for NPP Krško
10
313 213
MELCOR 1.8.6 nodalization scheme for NPP Krško
CV006 CV080 CV081 CV082 CV083 CV085
CV001
CV084 CV086
CV087
FL001 CV002
CV004 CV005 FL002
FL003 FL004
FL005
FL147 FL148
FL149 FL155 FL154
FL152 FL153
FL150 FL151
FL006 FL018
FL144 FL145
CV003 CV090
FL160
CV079
CV067 CV068 CV069 CV070 CV071 CV072 CV073 CV074 CV075 CV076 CV077 CV078
CV007 CV008 CV009 CV010 CV011 CV012 CV013 CV014 CV015 CV016 CV017 CV018
CV101 CV102
FL111 CV 105 CV103
FL102 FL301 FL302
CV301 CV302 CV303
FL304
FL303
CV304 CV305
FL307 FL306
CV308 CV307 CV306 FL305
FL106
FL107 CV 106
CV107 FL108 CV 108
RCP 1 FL164 CV110
FL 199 CV104
FL113 FL114
FL115 LOW COMP (CV702)
FL351
CV351 CV352 FL352
CV342
FL342 CV356
FL354
RPV
FL201 SG 1
CV201 CV202
FL202 FL401 FL402
CV401 CV402 CV403
FL407 FL406
CV408 CV407 CV406
FL206
FL207 CV 206
CV207 FL208
CV 208 RCP 2 FL264
CV210
FL 299 FL451
CV451 CV452
CV442
FL442 CV456
SG 2
PRZ
FL357
FL100 FL200
FL166 FL266
CV811 CV921
FL375 FL376 FL377 FL378 FL379 FL380
FL457
CV812 CV922
FL475 FL476 FL477 FL478 FL479 FL480
CV813 CV901
FL814
FL813
FL811 FL812
AFW 2
FL112
PRZ surge line
CV 105
FL736
RWST CV706
FL121 FL122
CV161 CV162
SG1C (CV708) FL157 CV706
FL716
ACC 1
CV 109 CV712 FL746 CV112
FL101
SG2C (CV709) FL257
ACC 2
CV 209
CV712 FL747FL726
CV212
FL265 FL165
FL748
CV712
Containment sump CV814
FL403 FL405
FL452
FL404 CV404
CV405 CV453 CV455
CV454 FL537
CV443
FL455 FL458
FL456
FL453 FL443
FL454
CV353 FL353
FL343 FL358
CV355
CV354 FL355
CV343
FL356
FL517
CV513
MFW 2
FL507
CV503
MFW 1
FL527
AFW 1
CV504 CV514
FL143
FL131
CV702 FL198
Parameter Unit NEK cycle 28 reference
RELAP5 (1000 s)
MELCOR (1000 s)
1. Pressure MPa
Pressurizer 15.513 15.513 15.517
Steam generator 6.281 6.275/6.286 6.19/6.16
Accumulator 4.93 4.93 4.93
2. Fluid Temperature K
Cold leg 558.75 559.49/559.25 559.36/559.16 Hot leg 597.55 596.82/596.82 596.94/596.94
Accumulator 322.0 322.0 322.0
Feedwater 492.6 492.7 492.6
3. Mass Flow kg/s
Core 8899.7 8925.3 8876.5
cold leg 4697.4 4711.7/4710.7 4683.8 /4686.2 main feedwater 544.5 540.9/544.7 538.9/541.8 main steam line 544.5 538.9/541.8 DC-UP bypass (0%) 0.0 0.0 0.0 DC-UH bypass (0.346%) 32.5 (0.346%) 35.0 (0.371%) 32.38 (0.346%) Buffle-barrel flow (1.0939%) 102.8
(1.094%)
103.1 (1.094%) 102.49 (1.094%) RCCA guide tubes (3.32%) 311.9 (3.32%) 359.2 (3.812%) 358.5 (3.826%)
Core cavity (0.5067%) 47.6 - -
4. Liquid level %
Pressurizer 55.7 55.8 55.8
Steam generator narrow range 69.3 69.3/69.3 69.3/69.4
5. Fluid Mass t
Primary system - 131.3 131.8
Steam generator (secondary) 47.0 49.1/48.9 48.08/48.07
6. Power MW
Core 1994.0 1994.0 1994.0
Transient results
Accident starts with the opening of the valve simulating 3 inch break in cold leg 1 (volume 110 in MELCOR, volume 275 in RELAP5)
Following the break opening RCS rapidly depressurizes. Reactor trip is initiated on low pressurizer pressure signal. Following actions are actuated on reactor trip: turbine trip, main steam isolation valve closure, main feedwater isolation, RC pump trip.
-Safety injection signal is actuated on low-2 pressurizer pressure signal; SI pumps are enabled with 5 seconds delay. Accumulator injection starts when RCS pressure drops below 4.93 MPa.
-Auxiliary feedwater is actuated on main feedwater isolation (60 seconds delay) -At transient begin SG PORV open for a short time following turbine trip.
-The heat produced in the core is primarily removed through the break, although in the first phase of the transient heat is also removed by steam
generators thus coupling the primary and secondary pressure. Along with RCS inventory depletion the heat transfer in steam generators stops and the primary pressure continues to decrease and decouples from secondary side.
- Core dry-out occurs for a short period (260-500 s) in MELCOR but fuel
cladding oxidation did not occur.
3 inch cold leg 1 LOCA – Time table of events
14
Event RELAP5/mod 3.3 MELCOR 1.8.6
Transient begin 0.0 0.0
Reactor trip, RC pumps trip 12.8 s (on low PRZ pressure) 14.5 s (on low PRZ pressure) Turbine trip, MSIV isolation, Main
feedwater isolation
12.8 s (on reactor trip signal) 14.5 s (on reactor trip signal) Safety injection signal 17.4 s (on low-2 PRZ pressure) 18.8 s (on low-2 PRZ pressure) Safety injection enabled 22.4 s (5 seconds delay) 23.8 s (5 seconds delay)
RWST empty - 5852
Safety injection-recirculation from sump - 6152 (5 minutes delay) Auxiliary feedwater injection enabled 72.8 (60 seconds delay) 74.5 (60 seconds delay)
Accumulator injection 650.0 690.0
Containment fan coolers enabled - 88.1 (35 seconds delay)
Containment spray - -
PCT temperature 610 K (steady state value) 711 K
Break mass flow rate
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Mass flow rate (kg/s)
0 50 100 150 200 250 300 350 400
MELCOR RELAP5
N EK 3 inch cold leg 1 L O C A
16
Pressurizer pressure
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Pressure (MPa)
2 4 6 8 10 12
14 MELCOR
RELAP5
N EK 3 inch cold leg 1 L O C A
Nuclear power
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Nuclear power (MW)
0 200 400 600 800 1000 1200 1400 1600
1800 MELCOR
RELAP5
N EK 3 inch cold leg 1 L O C A
18
Pressurizer and SG pressure
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Pressure (MPa)
2 4 6 8 10 12
14
PRZ pressure-MELCORSG 1 pressure-MELCOR SG 2 pressure-MELCOR PRZ pressure-RELAP5 SG 1 pressure-RELAP5 SG 2 pressure-RELAP5
N EK 3 inch cold leg 1 L O C A
Containment pressure
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Pressure (kPa)
110 120 130 140 150 160 170 180 190 200 210
MELCOR RELAP5
N EK 3 inch cold leg 1 L O CA
20
ECCS flow
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Mass flow rate (kg/s)
0 100 200 300 400 500 600 700 800 900 1000
MELCOR RELAP5
N EK 3 inch cold leg 1 L O C A
SI flow from RWST (MELCOR) SI flow from sump (MELCOR)
Cold leg temperature
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Temperature (K)
320 340 360 380 400 420 440 460 480 500 520 540 560
Tcold 1-MELCOR Tcold 2-MELCOR Tcold 1-RELAP5 Tcold 2-RELAP5
N EK 3 inch cold leg 1 L O C A
22
Hot leg temperature
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Temperature (K)
460 480 500 520 540 560
580 Thot 1-MELCOR
Thot 2-MELCOR Thot 1-RELAP5 Thot 2-RELAP5
N EK 3 inch cold leg 1 L O C A
Auxiliary feedwater flow
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
T ime (s)
Mass flow rate (kg/s)
0 2 4 6 8 10 12 14 16 18 20 22
AFW 1-MELCOR AFW 2-MELCOR AFW 1-RELAP5 AFW 2-RELAP5
N EK 3 inch cold leg 1 L O C A
24
SG mass
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
T ime (s)
Mass (kg)
45000 50000 55000 60000 65000 70000 75000
SG 1 mass-MELCOR SG 2 mass-MELCOR SG 1 mass-RELAP5 SG 2 mass-RELAP5
N EK 3 inch cold leg 1 L O C A
Fuel cladding temperature
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
T ime (s)
Temperature (K)
450 500 550 600 650 700
COR-TCL_0314-MELCOR COR-TCL_0114-MELCOR COR-TCL_0214-MELCOR COR-TCL_0414-MELCOR HTTEMP 111901016-RELAP5 HTTEMP 111901116-RELAP5 HTTEMP 111901216-RELAP5
N EK 3 inch cold leg 1 L O C A
3 inch cold leg break LOCA, Conclusion
• In MELCOR calculation larger break flow than in RELAP5 was obtained. This difference is mainly due to different choked flow models. Containment back pressure is lower in MELCOR than in RELAP5 due to fan coolers operation but this has a small influence on break flow.
• In MELCOR, lower RCS pressure and larger safety injection flow (LPIS) than in RELAP5 was obtained. This has influenced RCS temperatures.
• After reactor trip different heat transfer conditions in steam generator for RELAP5 and MELCOR were obtained. In MELCOR heat transfer from secondary to primary side was larger than in RELAP5 thus
resulting in lower secondary pressure. Pressure drop on secondary side was stopped first after terminating the auxiliary feedwater flow.
• In MELCOR, fuel cladding temperature has increased (max.
temperature=711 K) in the first phase of the transient, but fuel cladding oxidation did not occur.
26
NPP Krško Station Blackout (SBO) Calculation using MELCOR 1.8.6 and
MELCOR 2.2 Codes
28 Parameter Unit NEK cycle 28
reference
MELCOR 1.8.6 (1000 s)
MELCOR 2.2 (1000 s)
1. Pressure MPa
Pressurizer 15.513 15.517 15.517
Steam generator 6.281 6.19/6.16 6.19/6.16
2. Fluid Temperature K
Cold leg 558.75 559.36/559.16 559.36/559.16 Hot leg 597.55 596.94/596.94 596.94/596.94
Feedwater 492.6 492.6 492.6
3. Mass Flow kg/s
Core 8899.7 8876.5 8876.5
cold leg 4697.4 4683.8 /4686.2 4683.8 /4686.2 main feedwater 544.5 538.9/541.8 538.9/541.8 main steam line 544.5 538.9/541.8 538.9/541.8 DC-UP bypass (0%) 0.0 0.0 0.0 DC-UH bypass (0.346%) 32.5 (0.346%) 32.38 (0.346%) 32.39 (0.346%) Buffle-barrel flow (1.0939%) 102.8
(1.094%)
102.49 (1.094%) 102.49 (1.094%) RCCA guide tubes (3.32%) 311.9 (3.32%) 358.5 (3.826%) 358.6 (3.827%)
Core cavity (0.5067%) 47.6 - -
4. Liquid level %
Pressurizer 55.7 55.8 55.8
Steam generator narrow range 69.3 69.3/69.4 69.3/69.4
5. Fluid Mass t
Primary system - 131.8 131.8
Steam generator (secondary) 47.0 48.08/48.07 48.08/48.07
6. Power MW
Core 1994.0 1994.0 1994.0
Steam generator 1000.0 997.1/1002.6 997.1/1002.6
Transient Description
• Time=0: Reactor trip from 100% power, turbine trip, Main steam line isolation, Loss of main feedwater, RC pump trip, RC pump seal leakage
• Engineering Safety features (Auxiliary feedwater, Safety
Injection, Containment fan coolers, Containment Spray) are not available.
• Only passive components are available: Accumulators, Passive Autocatalytic Recombiners and Passive
Containment Filtered Vent System.
• SG safety valves and pressurizer safety valves are available.
• Accumulators will inject its content into RCS after RCS
pressure drop (either RPV failure or creep failure – hot leg,
PRZ surge line or SG tube)
NEK SBO: Time table of events
Event MELCOR 1.8.6 MELCOR 2.2
Transient begin 0.0 0.0
SG empty 3920 sec 3920 sec
Lower head failure 12438 sec 11768 sec
Begin of melt ejection 13950 sec 11800 sec
PCFV actuation 15020 sec 13350 sec
Begin of PCFV ON/OFF behavior 18170 sec 16440 sec
Lower head failure SG
depletion
Mass (t) 51015202530354045
0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000 T ime (s)
Pressure (MPa) 246810121416
PRZ pressure-MELCOR 1.8.6 PRZ pressure-MELCOR 2.2 SG 1 mass-MELCOR 1.8.6 SG 2 mass-MELCOR 1.8.6 SG 1 mass-MELCOR 2.2 SG 2 mass-MELCOR 2.2
N EK SB O
32
MELCOR 1.8.6: Fuel temperature 3rd ring
0 5000 10000 15000 20000 25000 30000
T ime (s) Temperature (K) 02004006008001000120014001600180020002200
COR-TCL_0314 A1 COR-TCL_0313 A1 COR-TCL_0312 A1 COR-TCL_0311 A1 COR-TCL_0310 A1 COR-TCL_0309 A1 COR-TCL_0308 A1 COR-TCL_0307 A1 COR-TCL_0306 A1 N EK SBO , M EL CO R 1.8.6
0 5000 10000 15000 20000 25000 30000
T ime (s) Temperature (K) 02004006008001000120014001600180020002200
COR-TCL_0314 A1 COR-TCL_0313 A1 COR-TCL_0312 A1 COR-TCL_0311 A1 COR-TCL_0310 A1 COR-TCL_0309 A1 COR-TCL_0308 A1 COR-TCL_0307 A1 COR-TCL_0306 A1 N EK SB O , M EL C O R 2.2
MELCOR 2.2: Fuel
temperature 3rd ring
0 50000 100000 150000 200000 250000 300000 T ime (s)
Pressure (kPa)
150 200 250 300 350 400 450 500 550
CVH-P_0701-MELCOR 1.8.6
CVH-P_0701-MELCOR 2.2
N EK SB O
34
0 50000 100000 150000 200000 250000 300000
T ime (s)
Temperature (K) 340360380400420440460CVH-TVAP_0701-MELCOR 1.8.6 CVH-TVAP_0701-MELCOR 2.2
N EK SB O
MELCOR 1.8.6: Pressurizer pressure, ejected mass to cavity
MELCOR 2.2: Pressurizer pressure, ejected mass to cavity
COR-MEJEC-TOT_0000 (kg) 01000020000300004000050000600007000080000
0 5000 10000 15000 20000 25000 30000
T ime (s) Pressurizer pressure (MPa) 246810121416
CVH-P_0103 A1 COR-MEJEC-TOT_0000 A2 N EK SB O , M EL C O R 1.8.6
COR-MEJEC-TOT_0000 (KG) 01000020000300004000050000600007000080000
0 5000 10000 15000 20000 25000 30000
T ime (s) Pressurizer pressure (MPa) 246810121416
CVH-P_0103 A1 COR-MEJEC-TOT_0000 A2 N EK SB O , M EL CO R 2.2
36
Cavity mass Removed hydrogen by PARs
0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 T ime (s)
Mass (t) 0102030405060708090100110120
CVH-MASS.1_0704-MELCOR 1.8.6 CVH-MASS.1_0704-MELCOR 2.2 N EK SBO
0 50000 100000 150000 200000 250000 300000
T ime (s) Mass (kg) 0100200300400500600700
ESF-PAR-IMH2_0001-MELCOR 1.8.6 ESF-PAR-IMH2_0002-MELCOR 1.8.6 ESF-PAR-IMH2_0003-MELCOR 1.8.6 ESF-PAR-IMH2_0004-MELCOR 1.8.6 ESF-PAR-IMH2_0001-MELCOR 2.2 ESF-PAR-IMH2_0002-MELCOR 2.2 ESF-PAR-IMH2_0003-MELCOR 2.2 ESF-PAR-IMH2_0004-MELCOR 2.2 N EK SB O
SBO, Conclusion
• MELCOR 2.2: Lower head failure at time=11768 sec and an immediate melt ejection to cavity that blocks flow path: sump pit- cavity. Water from the accumulators stays trapped in the cavity.
• MELCOR 1.8.6: Lower head failure at time=12438 sec and delayed melt ejection to cavity. Flow path: sump pit – cavity is free to expell a large amount of water from cavity to sump pit.
• As a consequence, in MELCOR 2.2 a larger amount of water
evaporated in cavity and lead to larger first peak in containment
pressure than in MELCOR 1.8.6. That has lead to delay in PCFV
activation in MELCOR 1.8.6. Later, the ON/OFF PCFV operation
had the same frequency for both codes.
38
FL 9
CV 3
CV 4 CV 4
CV 5
CV 10 CV 13 CV 6
CV 2
CV 1
CV 8 FL 21
FL 18 FL 7
FL 23 FL 24
FL 25
FL 10
FL 22
FL 8
FL 28 FL 26 FL 27 FL 4
FL 20
FL 16
FL 3
FL 15 FL 5
FL 2
CV
11 CV
9 CV
12
FL 29
FL 6 FL 34
FL 37
FL 30
FL 32
FL 31 FL 17
FL 33 Upper compartment sph
PRZ comp SG1 comp SG2 comp
Annulus
Lower comp Reactor
pool
ARV
Cavity Upper compartment cyl
CV 7
FL 35 FL 36
FL 1 FL 11
FL 19
FL 12
FL 14
FL 13 PCFV
Containment Failure
TS leak TS leak
RSump CSump
Sump pit
Door Failure FL 38
Cavity Modelling
Cavity Layout and the MCCI
Concrete decomposition
(at temperatures 873 – 1173 K):
CaCO
3→ CaO + CO
2(endothermic reaction) Iron rebar oxidation
(600 kg of iron in the 1 m
3of the concrete):
Fe + H
2O + 3.0 kJ/kg
(Fe)→ FeO + H
2Fe + CO
2+ 480 kJ/kg
(Fe)→ FeO + CO
40
0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 550000 600000 T ime (s)
Containment dome pressure (PA) 100000150000200000250000300000350000400000450000500000550000
CAV door open ARHR CAV door open Ref CI CAV door closed + 4in hole CAV door closed SB O - RB CO O L IN G AT 24 H - CI , ARHR, M HX - ES
0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 550000 600000 T ime (s)
Containment dome temperature (K) 340360380400420440460480500520
CAV door open ARHR CAV door open Ref CI CAV door closed + 4in hole CAV door closed SB O - RB CO O L IN G AT 24 H - CI , ARHR, M HX - ES
Gothic Multivolume Model
42
• Nodalization:
– 10 control volumes – 2 boundary conditions – 27 flow paths
– 74 heat structures – 2 RCFC units
(volumetric fan + HX)
– 1 spray train
Results
100 101 102 103
Time (s)
RCFC power (kW)
-18000 -16000 -14000 -12000 -10000 -8000 -6000 -4000 -2000 0
G 7.2b M 1.8.6
100 101 102 103
Time (s)
HTC steel liner inside (W/m2-K)
0 10 20 30 40 50 60 70 80 90 100
G 7.2b M 1.8.6
100 101 102 103
Time (s)
Containment dome pressure (kPa)
150 200 250 300 350 400
G 7.2b M 1.8.6
100 101 102 103
Time (s)
Containment dome temperature (C)
50 60 70 80 90 100 110 120 130
G 7.2b M 1.8.6
RN - Core AST for 3 NEK Cycles
44
Plant/time specific isotopic AST for core and SFP
0 100 200 300 400 500 600 700
Time (hr)
Activity (MCi)
0 10 20 30 40 50 60 70 80 90 100 110 120
N EK C Y C 29 M A A P AST
KR 85 KR 85M KR 87 KR 88 XE131M XE133 XE133M XE135 XE135M XE138 I131 I132 I133 I134 I135 CS134 CS136 CS137 RB 86 RB 88
46
0 100 200 300 400 500 600 700
Time (hr)
Actvity (MCi)
0 10 20 30 40 50 60 70 80 90 100
N EK C Y C 29 M A A P AST
RB 89 Y 90 Y 91 Y 92 Y 93 ZR 95 ZR 97 NB 95 MO 99 TE127 TE127M TE129 TE129M TE131M TE132 TE134 SB127 SB129 SR 89 SR 90
0 100 200 300 400 500 600 700 Time (hr)
Activty (MCi)
0 10 20 30 40 50 60 70 80 90
N EK C Y C 29 M A A P AST
SR 91 SR 92 BA139 BA140 RU103 RU105 RU106 RH105 TC 99M CE141 CE143 CE144 PU238 PU239 PU240 PU241
MAAP 4.0.9 and RADTRAD 3.03
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WGBST (KG/S) 0.511.522.533.544.55
60000 65000 70000 75000 80000 85000 90000 95000 100000 105000 110000 115000 120000 T ime (s)
() 0.10.20.30.40.50.60.70.80.90
FREL(1) A1 FREL(2) A1 FREL(3) A1 FREL(4) A1 FREL(5) A1 FREL(6) A1 FREL(7) A1 FREL(8) A1 FREL(9) A1 FREL(10) A1 FREL(11) A1 FREL(12) A1 FREL(13) A1 WGBST A2 REL EASE CAT EG O RY 8B = SG T R
0 .5 1 1.5 2 2.5 3
Time (day)
Leakage (%Vcont)
0 5 10 15 20 25 30 35 40 45 50
N EK SG T R
VOLFLOW_SGTR.dat
0 100 200 300 400 500 600 700
Activity (MCi)
0 50 100 150 200 250
N EK ES BB 1
Total activity released Activity in environemnt (decay) Activity containment
0 100 200 300 400 500 600 700
Activity in environment + plume (MCi)
0 .2 .4 .6 .8 1 1.2 1.4 1.6
N EK ES BB 1
activity_ecr01a_02.dat
RADTRAD and ARCON96 release and dispersion
Time interval ECR/TSC intake χ/Q (s/m3)
ECR/TSC roof χ/Q (s/m3)
0 – 2 h 2.15E-04 3.09E-04
2 – 8 h 1.46E-04 2.05E-04
8 – 24 h 6.91E-05 9.90E-05
1- 4 days 6.71E-05 9.05E-05
4 -30 days 5.18E-05 7.18E-05
RADTRAD compartment model used in calculation
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CONTAINMENT COMPARTMENT
(ECR) ENVIRONMENT
1 3 2
2 4 1
Leak to environment
Inflow (F2)
Intake F4
Recirculation filter F1
3
Exhaust (F3)
0 100 200 300 400 500 600 700
Time (h)
Immersion gamma dose (Gy)
.000 .005 .010 .015 .020 .025 .030 .035
N EK ES SG T R EC R
case01 case02 case03 case04
0 100 200 300 400 500 600 700
Time (h)
Gamm dose (Gy)
.00 .05 .10 .15 .20 .25 .30 .35 .40 .45 .50 .55
BB 1 SG T R ES Immersion gamma dose
bb1_sgtr_001n_gdose.dat bb1_sgtr_002n_gdose.dat bb1_sgtr_003n_gdose.dat bb1_sgtr_004n_gdose.dat bb1_sgtr_005n_gdose.dat bb1_sgtr_017n_gdose.dat bb1_sgtr_018n_gdose.dat
ECR HVAC filter doses, 4th HVAC sequence
100 101 102
Time (h)
Total filter activity (Ci)
0 100 200 300 400 500 600 700 800 900 1000 1100 1200
N EK ES SG T R EC R
sum_activity_ecr01d.dat sum_activity_ecr02d.dat sum_activity_ecr03d.dat sum_activity_ecr04d.dat
0 100 200 300 400 500 600 700
Gamma dose (Gy)
0 10 20 30 40 50 60 70 80 90 100 110 120
BB 1 M R dose from filter side extended
ecr01d_far_side_dose_100cm ecr01d_far_side_dose_200cm ecr01d_far_side_dose_400cm ecr01d_far_side_dose_600cm ecr01d_far_side_dose_800cm ecr04d_far_side_dose_100cm ecr04d_far_side_dose_200cm ecr04d_far_side_dose_400cm ecr04d_far_side_dose_600cm ecr04d_far_side_dose_800cm
Dose at BB1 top (hemisph R=200, 500m, homogenouse or X/Q)
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0 100 200 300 400 500 600 700
Time (h)
Dose (Gy)
0 2 4 6 8 10 12 14 16
B B 1 external dose SG T R ES, roof
external_ecr01d_xq_500m_bdose.dat external_ecr01d_xq_500m_gdose.dat external_ecr01d_500m_bdose.dat external_ecr01d_500m_gdose.dat external_ecr01d_200m_bdose.dat external_ecr01d_200m_gdose.dat
0 100 200 300 400 500 600 700
Time (h)
Dose (Gy)
0 2 4 6 8 10 12 14 16 18
B B 1 external dose SG T R ES, roof
external_ecr01d_xq_500m_bdose external_ecr01d_xq_500m_gdose external_ecr01dr_xq_500m_bdose external_ecr01dr_xq_500m_gdose
10-3 10-2 10-1 100 101 102
Time (h)
Concentration (Bq/m3)
100 101 102 103 104 105 106 107
B B 1 external dose SG T R ES, roof
external_ecr01d_200m_conc_Bq_m3 external_ecr01d_500m_conc_Bq_m3 external_ecr01d_xq_500m_conc_Bq_m3
0 100 200 300 400 500 600 700 Time (h)
Filter activity (Ci)
0 10 20 30 40 50 60
N EK ES SG T R ECR
filter_activity_ecr01d_Cs-134.dat filter_activity_ecr01d_Cs-136.dat filter_activity_ecr01d_Cs-137.dat
