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RELAP5/M3.3 – RELAP5/3D – FLUENT Calculations and Comparison of Reactor Downcomer Parameters
in PTS Analyses
Pavel KralMarek Bencik
Ladislav Vyskocil
International RELAP5-3D Users Group MeetingIdaho Falls, May 3-4, 2018
Outline
q Introduction and background
qTH remarks to PTS issue
qRelap5/Mod3.3 Input Model of VVER-440 for PTS calculations
qRelap5-3D Model of VVER-440 Reactor for PTS calculations
qCFD Fluent Model of VVER-440 for PTS calculations
qComparison of R5/M3 – FLUENT results of analyses of various PTS cases
in VVER-440
qComparison of R5/M3 – R5/3D results of analysis of MBLOCA with break
D200 mm in hot leg
qConclusions
Introduction and background
2
q Radiation embrittlement due to neutron fluence is the most significant aging mechanism for reactor pressure vessel (RPV)
q For the RPV lifetime assessment, material degradation limit (i.e. limits that are allowed to be approached by material degradation, without endangering the RPV integrity) has to be established
q This limit is established on the basis of pressurised thermal shock (PTS) analyses
q PTS is an event in NPP that is characterized by rapid cooldown in the primary coolant system with (usually) high primary pressure
q Thermal hydraulic analyses of PTS relevant events are the basis for PTS evaluation
q Application of advanced computational tools and method in system and mixing TH analyses has substantial effect on final PTS results
q Advanced system TH code RELAP (NRC 1D version implemented in UJV in 1990, DOE 3D version in 2004) is in UJV widely assessed and validated - more than 25 pre- and post-tests
q UJV Rez also cooperates in code development (DNBR correlations, end-valves, model of model for condensation of steam and steam-gas mixture in horizontal and inclined tubes) and in preparation of code couplings (containment code, CFD code etc.)
Introduction and background (cont’d)
3
General scheme of PTS evaluation:
Introduction and background (cont’d)
4
Computer codes used for PTS analyses of Czech NPPs in 1995-2005:system TH analysis: RELAP5 (later with 2D downcomer)
mixing calculation: REMIX/NEWMIXCATHARE 2D (for 2-phase cases)
structural calculation: SYSTUS COSMOS/M
Note: For some minor or special purposes UJV had used also the ATHLET, MELCOR, COCOSYS, FLUENT and FLUTAN computer codes.
Computer codes used for PTS reevaluation of Czech NPPs in 2016-2020:system TH analysis: RELAP5 (2D DC) or RELAP5-3D
mixing calculation: CFD FLUENT for predominantly single-phase casesDirect transfer of results from system RELAP5 / RELAP5-3Dcalculation of reactor DC (2D) to structural analysis
structural calculation: SYSTUS
Introduction and background (cont’d)
5
Major UJV Rez PTS projects:
PTS study for NPP Dukovany (VVER-440/213) Started in 1995, finished in 2004System TH analyses of 69 cases ® final PTS analyses of the 41 worst cases
PTS study for NPP Temelin (VVER-1000)Started in 2001, finished in 2005System TH analyses of 72 cases ® final PTS analyses of the 24 worst cases
PTS analyses for Mochovce NPP in Slovakia (VVER-440)Independent analyses for SAR, 2007-2008
PTS study for Armenian NPP (VVER-440)IAEA project, 2012-2013
PTS studies for South-Ukraine NPP (VVER-1000), Rovno NPP (VVER-1000, VVER-440), Khmelnitska NPP (VVER-1000)In frame of complex reassessment of RPV lifetime and LTO, 2012-2018
PTS re-evaluation for Czech NPPs Dukovany and Temelin (2016 – 2020)The most significant PTS scenarios have been / will be recalculated according to current methodology, approaches and models
Introduction and background (cont’d)
UJV co-authoring in preparation of PTS guidelines: § Guidelines on Pressurized Thermal Shock Analysis for WWER Nuclear Power Plants, IAEA-EBP-
WWER-08, 1997 (Revision 2006)
§ Unified Procedure for Lifetime Assessment of Components and Piping in VVER NPPs, VERLIFE project of the 5th Framework Programme of the EU, 2003 (Revision 2008)
§ Preparation of “PTS Textbook”, IAEA→NUGENIA. Draft version.
UJV participation in PTS benchmarks and other assessment work: § IAEA Pressurized Thermal Shock Benchmark (PRZ SV inadvertent opening), 1997-1999
(UJV system TH analysis selected as reference results for following mixing and structural calcs)
§ Unsymmetrical cooldown of 1 loop of VVER-440 (measured test from Dukovany NPP)
Papers: § Macek, Muhlbauer, Krhounková, Král, Malačka: Thermal Hydraulik Analyses of NPPs with VVER-
440/213 for the PTS Condition Evaluation. NURETH-8. 1997
§ Král, Pištora: Impact of ECCS Design of VVER Reactors on PTS Issue. Internatioinal TopicalMeeting 2004 - Prague. October 2004.
§ Pištora V, Král P.: PTS Evaluation for Czech Nuclear Power Plants of WWER Type. 2009 ASME Conference. Prague July 2009.
§ Pistora, Zamboch, Král, Vyskocil: PTS Re-Evaluation Project for Czech NPPs. Fourth International Conferences on NPP Life Managment (PLiM), IAEA, October 2017, Lyon
6
7
Thermal Hydraulic Remarks to PTS issue
TH remarks to PTS issue
The pressurized thermal shock (PTS) events are characterized by rapid temperaturedecrease of the primary coolant, particularly in the reactor downcomer, and bysubsequent cooldown of the reactor pressure vessel (RPV) wall leading to thermalstresses in the RPV wall, that could be loaded at the same time by inner pressure.
Temprerature profiles in VVER-1000 RPV wall in initial phase of LBLOCA (safety analysis for core cooling, min. ECCS)
100
120
140
160
180
200
220
240
260
280
300
2.05 2.1 2.15 2.2 2.25 2.3radial position [m]
tem
pera
ture
[C]
0 s 5 s 20 s 50 s 100 s 300 s
Temprerature profiles in VVER-1000 RPV wall in initial phase of LBLOCA (PTS analysis from HZP, max. ECCS)
100
120
140
160
180
200
220
240
260
280
300
2.05 2.1 2.15 2.2 2.25 2.3radial position [m]
tem
pera
ture
[C]
0 s 5 s 20 s 50 s 100 s 300 s
Fast changes of temprerature profile in reactor vessel wall during LBLOCA analyses
8
TH remarks to PTS issue (cont’d)
9
The RPV cooldown is often nonuniform, which is caused either by ECCS injection or by rapidasymmetric cooldown via a steam generator (plus symmetrical cooldown due to RCS rapiddepressurization and coolant evaporation in LOCA).
So-called „cold plumes“ (typical for SBLOCA etc.), respectively „cold stripes“ (typical forearly phase of LBLOCA) or „cold sectors“ (typical for MSLB) could be formed andconsequently increase the thermal stresses in the RPV wall.
RELAP5/M3.3 and CATHARE.2D temperature fields at inner surface of reactor vessel in SBLOCA (VVER-440, break D50 in hot leg, time 120 s with injection of 3 HPSI, 2001)
chan.btwn.CL1 chan.CL2 chan.CL3 chan.HAs chan.CL4 chan.CL5 chan.CL6 chan.chan.btwn.
vol.1
vol.2 (inlet from CLs elevation)
vol.3
vol.4 (core region)
vol.5 (core region)
vol.6
vol.7
vol.8 (reactor eliptical bottom)
260-270250-260240-250230-240220-230210-220200-210190-200180-190170-180160-170150-160140-150130-140120-130110-120100-11090-10080-9070-8060-7050-6040-50
Temperature
scale [C]:
2 13456
Fig.H50n-R01 DC coolant temperatures in RELAP5/M3.2 calculation at time = 120 s
(HL1 break D50 from N100%, equidistant projection)
0.00 22.50 45.00 67.50 90.00 112.50 135.00 157.50 180.00 202.50 225.00 247.50 270.00 292.50 315.00 337.50 360.00
8.358.007.657.306.966.616.265.915.575.224.874.524.173.833.483.132.782.442.091.741.391.050.700.350.00
circumferential angle [degree]
height [m]
260.00-270.00
250.00-260.00
240.00-250.00
230.00-240.00
Fig.H50n-C01 DC coolant temperatures in CATHARE calculation at time = 120 s
5 6 4 1 2 3
Temperature scale [C]:
TH remarks to PTS issue (cont’d)
10
TH remarks to PTS issue (cont’d)
11
SBLOCAD90 in hot leg – CFD predicted contours of static temperature in axial section:
TH remarks to PTS issue (cont’d)
12
Reactor pressure vessel of VVER-1000 with position of welds No. 3 and 4 versus core elevation
TH remarks to PTS issue (cont’d)
13
Reactor pressure vessel (RPV) is the most important component of a nuclearpower plant. Its lifetime is a limiting factor for the lifetime of the entire NPP.So the evaluation of PTS is a crucial task of the nuclear safety.Rupture of RPV and consequent LOCA with break in middle or lower part ofthe downcomer could lead to LOCA with nearly impossible cooling of thecore (= inevitable core damage).
Schematics of VVER (PWR) primary circuit and steam generators during normal operation
TH remarks to PTS issue (cont’d)
14
Main TH phenomena deteriorating pressurized thermal shock:
(-) Fast temperature decrease in reactor downcomer (DC).
(-) Low final temperature in DC (especially with: high initial temperature).
(-) High primary pressure during the process.
(-) Low flowrate or flow stagnation in loops with ECCS connection.
(-) Nonhomogeneous coolant temperature field in reactor downcomerfrom SI injection (cold plumes, cold stripes) or from non-symmetriccooldown (cold sectors).
(-) Big differences in heat transfer coefficients (HTC) at inner wall of RPV.
(-) Interactions of neighboring cold plumes.
These general deteriorating TH factors are important in selecting conservative initial and boundary conditions for TH calculations.
15
Models of VVER-440:q Relap5/Mod3.3 q Relap5-3D q Fluent
Relap5/Mod3.3 Input Model of VVER-440
16
Important features of the model from the PTS point of view:
Ø Detailed and complex model of RCS, ECCS, SGs, MSS, FW systems
Ø 1800 hydraulic control volumes and 2200 junctions, 1800 heat structures with 9800 mesh points, 2700 control variables with 1800 trips
Ø Nodalization based on R5 manual guide, know-how of wide R5 users community, experience from own code validation against VVER-design experimental facilities, modelling of NPP tests etc.
Important features of the model from the PTS point of view:
Ø Individual modeling of all primary loops (i.e. 6 loops in case of VVER-440)
Ø 2-D nodalization of reactor downcomer applied in selected transients(for correct prediction of flow coastdown in individual loops etc.)
Ø Detailed modeling of ECCS system(hydroaccumulators + HA lines, SI tanks, SI pumps, discharge lines)
Ø Detailed modeling of SGs (multi-layer tubing) and Main Steam System (important for the MSLB)
Relap5/Mod3.3 Input Model (cont’d)
Nodalization of NPP Dukovany Reactor Coolant System and ECCS(VVER-440/213, version with 2D downcomer, only 1 of 6 loops depicted)
17
Relap5/Mod3.3 Input Model (cont’d)
18
Nodalization of Main Steam System (MSS) of NPP Dukovany with VVER-440/213
Relap5/Mod3.3 Input Model (cont’d)
19
Nodalization of Feedwater System of NPP Dukovany with VVER-440/213
Relap5_3D Model of VVER-440
20
q The RELAP5/MOD3 input model for VVER-440 created in UJV Rez was used as a base for the RELAP5-3D input deck.
q The reactor vessel is described by the following R5-3D components:§ 1 MULTID (3D) object representing reactor DC, LP, core bypass, UP, UH
(17 axial levels, 4 radial sectors, 8 azimuthal sectors)§ 49 PIPES representing 349 fuel assemblies
q The model prepared for PTS analyses uses point-kinetics model of reactor core (no need for 3D neutron kinetics in PTS analyses)
Relap5_3D Model of VVER-440
21
Nodalization of VVER-440 RCS with 3D model of reactor(only 1 of 6 primary loops depicted)
15
14
13
11
10
9
8
7
6
5
4
3
2
1
16
17
HL 4
CL 4
MSH
TJ20
HP
CL 2
TJ40
HP
FWEFW
TH20
CL 3
HP
TJ60
HP
CL 5
UPPER PLENUM
MIV
TH60
HP
DOWNCOMER DOWNCOMERUPPER PLENUM
HEATERS
(TK)
SPRAY
PRESSURIZER
PV 2
PV 1
RV
YP11S01/S02
TF10
SM
REACTOR STEAM GENERATOR 1
MCP
TY11
CL 1/2 CL 5/3 CL 6/4
MIV
TH40
HP
CL 5/3
TE SYSTEM
HL 1
CL 1
TK SYSTEM
CL 1/2 CL 6/4PT
TH13 TH12 TH11 TH10
125
440
449447
446
441
442
448
443
457456 450
452
458
454453
(202-05)
(226-01)
370
379377
376
371
372
378
373
374
375
(156)
380
389387
386
381
382
388
383
384
385
(186)
390
399397
396
391
392
398
393
394
395
(256)
04 03
02
02
101
127
121
105106
02
05
02
03
0402
03
04
301
300
303
310
311 312
01
02
03
05
06
07
10 10
05
07
06
0404
03
02
01
328
326
325
321
324
323
322
314315
330 338
336
333
331
332
335
316317
340
347342
345 349
344
343
350
348
346
03
04
05
02
01
01
351(S01)
02352353
(S02)
354
356
355(S15)
357(S17)
358
HP
319
103123
02
01
100
128 12602 124
102
050403
02
12202
03
104
327
707
120
07
700
702
01
02
04
05
06
08
09
03
07
703
01
02
03
04
05
06
705 706
01
02
03
04
05
06
07 70107
03
07
06
05
04
03
02
01
108
01
02
03
04
05
06
118
119109
11710090807060504030201 11510090807060504030201 116
10090807060504030201 114
10090807060504030201 113
10090807060504030201 112
06 07 08 09 100504030201 111110
03
304
302
320
306
305
01
190
191
194 197 299
192
193
195
196
198
199
(122/152) (252/182) (282/222)
291
290 292 294 296
293 295 297
(254/184) (284/224)(124/154)329
420 410 400430
425
426
422
423
424
435
436
432
433
434
415
416
417
412
413
414
418438427
428
437
408
402
403
404
405
480
489487
486
481
482
483
488
407
490
497
498494
492
493
406
470
476
477
478
472
473
474
496
460
469467
466
461
462
468
463
105
Relap5_3D Model of VVER-440
22
1
2
3
4
5
6
7
8
9
10
11
13
14
15
16
17
1
23
4
5
67
8
1432
1
23
4
5
67
8
A - A
B - B
B
A A
BCL 2
CL 1
CL 3CL4
CL 5
HAHA
CL 6
32 41
HL
CL
RELAP5 modelPressure vessel
DC
LP
CORE
UP
Fuel
Reflector
Fuel assembly number
RELAP5-3D channel (pipe)
310
261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278
279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295
296 298 299 300 301 302 303 304 305 306 307 308 309 311297
312 313 316 318 319 320314 315 317 321 322 323 324
325 326 327 328 329 330 331 332 333 334 335 336
337 338 339 340 341 342 343 344 345
346 347 348 349
90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 107 108106
175
1 2 3 4
5 6 7 8 9 1311 1210
14 15 16 17 18 19 20 21 22 23 24 25
38373635343332313029282726
39 40 41 42 43 44 48474645 49 50 51 52 53 54
55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
72 73 75 76 77 78 79 80 8174 82 83 84 85 87 88 8986
126125124123122121120119118117116115114113112111110109
127 128 129 130 131 132 133 134 135 136 137 138 140139 141 142 143 144 145
146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165
166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184
185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 204203
205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223
224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241
248242 243 244 245 246 247 249 250 251 252 253 256 257 258254 255 260259
84
93 96
95
85
21
86
9192
94
2122 23
24
25
26
273132
33
34
35
36
41
42
4344
46 45
51
52
53
54
55
56
6162
64
63
66
65
7172
73
7475
76
81
82
83
Reactor vessel and core nodalization
CFD Fluent Model of VVER-440 for PTS Calculations
23
Computational Domain
2.1M computational cells, 1.4M cells in fluid domain, 0.7M cells in solid wallsCalculations of long transients (~1hour or longer)Initial and boundary conditions for CFD are taken over from RELAP5 simulation.Goal of the CFD simulation: temperature fields on wetted walls in cold legs and on RPV wall in downcomerDepending on the solved case, some parts can be deleted from thecomputational domain, e.g. cold legs without operating injections.
TJ20, 40, 60:HP ECCS injections
TH40:LP ECCS injection
CL1
CL2
CL3CL4
CL5
CL6
TJ20
TJ40
TJ60
TH40
CFD Fluent Model of VVER-440 for PTS Calculations
24
Computational mesh in the fluid domain
Wall-adjacent cells are 1mm thin.Turbulence is modelled with the realizable k-e model.
Comparison of R5/M3 – FLUENT results of various PTS analyses for VVER-440
25
Comparison of R5/M3 – FLUENT results of various PTS analyses for VVER-440
26
Parameters transferred from system TH analysis to mixing CFD calculation:
§ Reactor pressure and temperature (lower plenum)
§ Coolant velocity, temperature and void at SG outlet
§ Coolant velocity, temperature and void at reactor inlet
§ HPIS flow to cold legs and temperature (3+3 par.)
§ LPIS flow to cold leg and temperature
§ Hydroaccumulators flow to downcomer and temperature
Comparison of R5/M3 – FLUENT results of various PTS analyses for VVER-440
27
SBLOCA with 90 mm break in hot leg from full power with 3/3 HPIS in operation:
Fig. 22 Temperatures of wetted surface on the RPV weld 5/6
Note: The weld 5/6 is located next to the reactor core, 3.74 m below axes of the cold legs.
020406080
100120140160180200220240260280
0 400 800 1200 1600 2000 2400 2800 3200 3600
tem
pera
ture
[°C
]
time[s]
Relap - DC1Relap - DC2Relap - DC3Relap - DC4Relap - DC5Relap - DC6Fluent - minFluent - max
Comparison of R5/M3 – FLUENT results of various PTS analyses for VVER-440
28
SBLOCA with 30 mm break in hot leg from zero power with 3/3 HPIS in operation:
Fig. 22 Temperatures of wetted surface on the RPV weld 5/6
Comparison of R5/M3 – FLUENT results of various PTS analyses for VVER-440
29
MSLB at zero power with 3/3 HPIS
Fig. 22 Temperatures of wetted surface on the RPV
Comparison of R5/M3 – FLUENT results of various PTS analyses for VVER-440
30
PRISE with SG internal manifold failure from HZP and with 1/3 HPIS
Fig. 22 Temperatures of wetted surface on the RPV
Comparison of R5/M3 – FLUENT results of various PTS analyses for VVER-440
31
Inadvertent opening of PRZ SV at full power and its re-closure at 1800 s with 3/3 HPIS
Fig. 22 Temperatures of wetted surface on the RPV
Comparison of results of R5/M3 – R5/3D analysis of medium break LOCA with
break D200 mm in hot leg
32
Comparison of R5/M3 – R5/3D results of analysis of
MBLOCA with break D200 mm in hot leg
33
System TH calculation of medium-break LOCA in VVER-440 with 2D
model of DC:
§ Starting from full power (1502 MWt)
§ Break D200 mm in hot leg of loop No.1
§ Full availability of ECCS (3/3 HPIS, 4/4 ACCU, 3/3 LPIS)
§ Conservative assumptions for PTS analysis
§ Calculations with RELAP5/MOD3.3 and with RELAP5-3D
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
34
PARAMETR UNITVALUER5/M3.3
VALUER5-3D
Reactor power MW 1501,8 1502,0Reactor inlet coolant temperature °C 270,1 270,1Reactor outlet coolant temperature °C 303,0 304,0Reaktor coolant flow kg/s 8623 8636
Core bypass kg/s 733,3(8,5 %)
734(8,5 %)
Primary pressure (HL) MPa 12,66 12,66PRZ heaters power kW 180 360Pressurizer level m 6,90 7,02
SG pressure MPa 4,90 ÷ 4,93 4,91 ÷ 4,97MSH pressure MPa 4,72 4,72FW pressure MPa 6,63 6,45FW temperature °C 229,2 223,4SG collapsed level m 1,86 ÷ 1,90 1,92Steam output kg/s 137,6 ÷ 138,9 135,2 ÷ 137,0
Initial parameters
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
35
EventTime [s]
RELAP5-3DTime [s]
RELAP5-3D
Initial event = break D200 mm in hot leg of loop No.1 0 0
LOOP 0 0
Reactor SCRAM 0,5 0,5
Start of 3/3 HPIS injection 22 30
Start of 4/4 ACC injection 131 126End of ACC injection 352 280
Start of 3/3 LPIS injection 367 300
End of calculation 3600 3600
Timing of main events:
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
36
Primary and secondary pressure
RELAP5/MOD3 RELAP5-3D
000.0E+0
2.0E+6
4.0E+6
6.0E+6
8.0E+6
10.0E+6
12.0E+6
14.0E+6
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
pres
sure
[Pa]
primary pressure (PRZ) sec. pressure (SG1)
000.0E+0
2.0E+6
4.0E+6
6.0E+6
8.0E+6
10.0E+6
12.0E+6
14.0E+6
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
pres
sure
[Pa]
primary pressure (PRZ) sec. pressure (SG1)
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
37
Break and ECCS flow
RELAP5/MOD3 RELAP5-3D
-500
0
500
1000
1500
2000
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
mas
s flo
w r
ate
[kg/
s]break flow total ECCS injection
-500
0
500
1000
1500
2000
2500
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
mas
s flo
w r
ate
[kg/
s]
break flow total ECCS injection
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
38
Injection of individual ECCS systems
RELAP5/MOD3 RELAP5-3D
0
200
400
600
800
1000
1200
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
mas
s flo
w r
ate
[kg/
s]
HPIS LPIS ACCUM
0
200
400
600
800
1000
1200
1400
1600
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]m
ass
flow
rat
e [k
g/s]
HPIS LPIS ACCUM
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
39
Reactor flow
RELAP5/MOD3 RELAP5-3D
-2000
0
2000
4000
6000
8000
10000
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
mas
s flo
w r
ate
[kg/
s]reactor flow (LP)
-2000
0
2000
4000
6000
8000
10000
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
mas
s flo
w r
ate
[kg/
s]
reactor flow (LP)
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
40
Reactor level
RELAP5/MOD3 RELAP5-3D
0
2
4
6
8
10
12
14
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
leve
l [m
]collapsed level in innner reactor collapsed level in downcomer
0
2
4
6
8
10
12
14
16
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
leve
l [m
]
collapsed level in innner reactor collapsed level in downcomer
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
41
Reactor power and reactivity
RELAP5/MOD3 RELAP5-3D
0.00
20.00
40.00
60.00
80.00
100.00
120.00
-500 0 500 1000 1500 2000 2500 3000 3500 4000time [s]
reac
tor
pow
er [%
]
-100
-80
-60
-40
-20
0
20
reac
tivity
[$]
reactor total power reactivity
0.00
20.00
40.00
60.00
80.00
100.00
120.00
-500 0 500 1000 1500 2000 2500 3000 3500 4000time [s]
reac
tor
pow
er [%
]
-120
-100
-80
-60
-40
-20
0
20
reac
tivity
[$]
reactor total power reactivity
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
42
Coolant temperatures in reactor
RELAP5/MOD3 RELAP5-3D
0
20
40
60
80
100
120
140
160
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
tem
pera
ture
[o C]
core inlet core outlet (average) upper plenum saturation temperature
0
20
40
60
80
100
120
140
160
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
tem
pera
ture
[o C]
core inlet core outlet (average) upper plenum saturation temperature
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
43
Coolant temperatures at reactor inlet
RELAP5/MOD3 RELAP5-3D
0
50
100
150
200
250
300
350
-500 0 500 1000 1500 2000 2500 3000 3500 4000time [s]
tem
pera
ture
[C]
CL1 CL2 CL3 CL4 CL5 CL6 saturation temp.
0
50
100
150
200
250
300
350
-500 0 500 1000 1500 2000 2500 3000 3500 4000time [s]
tem
pera
ture
[C]
CL1 CL2 CL3 CL4 CL5 CL6 saturation temp.
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
44
Coolant temperatures around downcomer (at core elevation)
RELAP5/MOD3 RELAP5-3D
0.00
50.00
100.00
150.00
200.00
250.00
300.00
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]
tem
per
atu
re [
C]
pod smyčkou č.2 pod smyčkou č.3 pod HDA pod smyčkou č.4
pod smyčkou č.5 pod smyčkou č.6 kanál mezi smyč. 1 a 6 pod smyckou c.1
0.00
50.00
100.00
150.00
200.00
250.00
300.00
-500 0 500 1000 1500 2000 2500 3000 3500 4000
time [s]te
mpe
ratu
re [C
]pod smyčkou č.2 pod smyčkou č.3 pod HDA pod smyčkou č.4
pod smyčkou č.5 pod smyčkou č.6 kanál mezi smyč. 1 a 6 pod smyckou c.1
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
45
Coolant temperatures field in downcomer at 90 s (HPSI dominating)
RELAP5/MOD3 RELAP5-3D
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
46
Coolant temperatures field in downcomer at 250 s (ACCUM injection dominating)
RELAP5/MOD3 RELAP5-3D
Comparison of R5/M3 – R5/3D results of analysis of MBLOCA with break D200 mm in hot leg
47
Preliminary conclusions from calculations of MBLOCA D200 with Relap5/Mod3.3 and Relap5-3D and comparison of results:
§ Good overall agreement
§ Major difference is the stronger ACCUM injection and faster filling of reactor vessel UP and UH – probably due to differences in predicted condensation in UP – which may be caused by finer nodalization of UP in Relap5-3D model
§ Further analysis of results needed
Conclusions
48
q The paper presents briefly overall UJV approach to PTS evaluation
q Increasing computational power enables wider deployment of CFD in PTS analyses
q For predominantly single-phase cases, the system TH analysis with Relap5/Mod3.3 (and 2D nodalization of reactor DC) is followed by CFD mixing calculation of downcomer and cold legs domainØ Surprisingly good agreement between Relap5 and Fluent in prediction
of temperature field in DC
q For two-phase cases the result from system TH analysis with 2D downcomer nodalization (Relap5/Mod3.3) have been directly transferred to integrity calculations
q Application of Relap5-3D is a new progressive step in PTS method applied to Czech NPPs (just started)
q Another direction of progress in UJV Rez thermal-hydraulic methods for PTS evaluation is the coupling of system TH code and CFD code – for predominantly single phase cases (not presented in the paper)
49
Thank you for your attention
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