relap53.3-relap5-3d-fluent comparison for pts analyses documents... · relap5/m3.3 –relap5/3d...

50
RELAP5/M3.3 – RELAP5/3D – FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses Pavel Kral Marek Bencik Ladislav Vyskocil International RELAP5-3D Users Group Meeting Idaho Falls, May 3-4, 2018

Upload: others

Post on 15-Aug-2020

17 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 2: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 3: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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.)

Page 4: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

Introduction and background (cont’d)

3

General scheme of PTS evaluation:

Page 5: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 6: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 7: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 8: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

7

Thermal Hydraulic Remarks to PTS issue

Page 9: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 10: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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]:

Page 11: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

TH remarks to PTS issue (cont’d)

10

Page 12: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

TH remarks to PTS issue (cont’d)

11

SBLOCAD90 in hot leg – CFD predicted contours of static temperature in axial section:

Page 13: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 14: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 15: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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.

Page 16: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

15

Models of VVER-440:q Relap5/Mod3.3 q Relap5-3D q Fluent

Page 17: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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)

Page 18: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 19: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

Relap5/Mod3.3 Input Model (cont’d)

18

Nodalization of Main Steam System (MSS) of NPP Dukovany with VVER-440/213

Page 20: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

Relap5/Mod3.3 Input Model (cont’d)

19

Nodalization of Feedwater System of NPP Dukovany with VVER-440/213

Page 21: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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)

Page 22: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters 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

Page 23: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 24: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 25: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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.

Page 26: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

Comparison of R5/M3 – FLUENT results of various PTS analyses for VVER-440

25

Page 27: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 28: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 29: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 30: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 31: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 32: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 33: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

Comparison of results of R5/M3 – R5/3D analysis of medium break LOCA with

break D200 mm in hot leg

32

Page 34: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 35: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 36: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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:

Page 37: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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)

Page 38: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 39: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 40: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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)

Page 41: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 42: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 43: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 44: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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.

Page 45: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 46: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 47: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 48: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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

Page 49: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

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)

Page 50: RELAP53.3-RELAP5-3D-Fluent comparison for PTS Analyses Documents... · RELAP5/M3.3 –RELAP5/3D –FLUENT Calculations and Comparison of Reactor Downcomer Parameters in PTS Analyses

49

Thank you for your attention

www.ujv.cz