FER MELCOR Activities - Paul Scherrer Institute · FER MELCOR Activities. The 10th Meeting of the „European MELCOR User Group”, Zagreb, Croatia, 25–27 April, 2018 Content:

FER MELCOR ActivitiesFER MELCOR Activities

Presenter: Davor Grgić

Vesna Benčik, Davor Grgić, Siniša Šadek, Štefica VlahovićFaculty of Electrical Engineering and Computing (FER)University of Zagreb, Croatia

The 10th Meeting of the „European MELCOR User Group”, Zagreb, Croatia, 25–27 April, 2018


• 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

CV083CV085

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

CV105

CV103

FL102

FL301

FL302

CV301

CV302

CV303

FL304

FL303

CV304 CV305

FL307

FL306

CV308

CV307

CV306

FL305

FL106

FL107

CV106

CV107FL108

CV108

RCP 1FL164

CV110

FL199

CV104

FL113 FL114

FL115

LOWCOMP

(CV702)

FL351

CV351

CV352

FL352

CV342

FL342

CV356

FL354

RPV

SG 1FL201CV201CV202

FL202

FL401

FL402

CV401

CV402

CV403

FL407

FL406

CV408

CV407

CV406

FL206

FL207

CV206

CV207

FL208

CV208

RCP 2FL264

CV210

FL299

FL451

CV451

CV452

CV442

FL442

CV456

SG 2

PRZ

FL357

FL100FL200

FL166FL266

CV811

CV921

FL375FL376FL377FL378FL379FL380

FL457CV812

CV922


CV813

CV901

FL814

FL813

FL811FL812

AFW 2

FL112

PRZ surge line

CV105

FL736

RWST CV706

FL121

FL122

CV161

CV162

SG1C(CV708)

FL157

CV706

FL716

ACC1

CV109

CV712

FL746

CV112

FL101

SG2C(CV709)

FL257

ACC2

CV209

CV712

FL747 FL726

CV212FL265 FL165

FL748

CV712

Containment sump

CV814

FL403FL405FL452

FL404CV404CV405CV453

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 1CV504CV514

FL143

FL131

CV702

FL198

5

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.7


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 21275. NUMBER OF CORE ACTIVE

STRUCTURES12

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 7329. NUMBER OF TRIPS

- variable 197- logical 221- total 418

10. OVERALL PRIMARY SIDE VOLUME (m3)

195.3


Parameters of MELCOR 1.8.6 nodalization

9

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 7315. NUMBER OF CORE ACTIVE

STRUCTURES27

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

11


CV006

CV080

CV081

CV082

CV083CV085

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

CV105

CV103

FL102

FL301

FL302

CV301

CV302

CV303

FL304

FL303

CV304 CV305

FL307

FL306

CV308

CV307

CV306

FL305

FL106

FL107

CV106

CV107FL108

CV108

RCP 1FL164

CV110

FL199

CV104

FL113 FL114

FL115

LOWCOMP

(CV702)

FL351

CV351

CV352

FL352

CV342

FL342

CV356

FL354

RPV

SG 1FL201CV201CV202

FL202

FL401

FL402

CV401

CV402

CV403

FL407

FL406

CV408

CV407

CV406

FL206

FL207

CV206

CV207

FL208

CV208

RCP 2FL264

CV210

FL299

FL451

CV451

CV452

CV442

FL442

CV456

SG 2

PRZ

FL357

FL100FL200

FL166FL266

CV811

CV921


FL457CV812

CV922


CV813

CV901

FL814

FL813

FL811FL812

AFW 2

FL112

PRZ surge line

CV105

FL736

RWST CV706

FL121

FL122

CV161

CV162

SG1C(CV708)

FL157

CV706

FL716

ACC1

CV109

CV712

FL746

CV112

FL101

SG2C(CV709)

FL257

ACC2

CV209

CV712

FL747 FL726

CV212FL265 FL165

FL748

CV712

Containment sump

CV814

FL403FL405FL452

FL404CV404CV405CV453

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 1CV504CV514

FL143

FL131

CV702

FL198

12

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 Steam generator 1000.0 995.9/1003.0 997.1/1002.6

Results of steady state calculation

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.

13


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, Mainfeedwater 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


15

Break mass flow rate


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Mas

s flo

w ra

te

(kg/

s)

0

50

100

150

200

250

300

350

400

MELCOR RELAP5

N E K 3 inch cold leg 1 L O C A

16

Pressurizer pressure


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Pres

sure

(M

Pa)

2

4

6

8

10

12

14 MELCOR RELAP5


17Nuclear power


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Nucle

ar p

ower

(M

W)

0

200

400

600

800

1000

1200

1400

1600

1800 MELCOR RELAP5


18Pressurizer and SG pressure


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Pres

sure

(M

Pa)

2

4

6

8

10

12

14 PRZ pressure-MELCOR SG 1 pressure-MELCOR SG 2 pressure-MELCOR PRZ pressure-RELAP5 SG 1 pressure-RELAP5 SG 2 pressure-RELAP5


19Containment pressure


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Pres

sure

(k

Pa)

110

120

130

140

150

160

170

180

190

200

210

MELCOR RELAP5

N EK 3 inch cold leg 1 L O C A

20ECCS flow


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Mas

s flo

w ra

te

(kg/

s)

0

100

200

300

400

500

600

700

800

900

1000

MELCOR RELAP5


SI flow from RWST (MELCOR) SI flow from sump (MELCOR)

21

Cold leg temperature


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Tem

pera

ture

(K

)

320

340

360

380

400

420

440

460

480

500

520

540

560Tcold 1-MELCOR Tcold 2-MELCOR Tcold 1-RELAP5 Tcold 2-RELAP5


22Hot leg temperature


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Tem

pera

ture

(K

)

460

480

500

520

540

560

580Thot 1-MELCOR Thot 2-MELCOR Thot 1-RELAP5 Thot 2-RELAP5


23Auxiliary feedwater flow


0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000T ime (s)

Mas

s flo

w ra

te

(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

24SG mass


0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000T ime (s)

Mas

s (

kg)

45000

50000

55000

60000

65000

70000

75000

SG 1 mass-MELCOR SG 2 mass-MELCOR SG 1 mass-RELAP5 SG 2 mass-RELAP5


25

Fuel cladding temperature


0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000T ime (s)

Tem

pera

ture

(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


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


2727

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

Results of steady state calculation

2929

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

31Pressurizer pressure and SG mass

Lower head failureSG depletion

Mas

s (

t)

510

1520

2530

3540

45

0 5000 10000 15000 20000 25000 30000 35000 40000 45000 50000T ime (s)

Pres

sure

(M

Pa)

24

68

1012

1416

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 30000T ime (s)

Tem

pera

ture

(K

)

020

040

060

080

010

0012

0014

0016

0018

0020

0022

00

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 E K SB O , M E L C O R 1.8.6

0 5000 10000 15000 20000 25000 30000T ime (s)

Tem

pera

ture

(K

)

020

040

060

080

010

0012

0014

0016

0018

0020

0022

00

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 E K SB O , M EL C O R 2.2

MELCOR 2.2: Fuel temperature 3rd ring

33Containment (upper compartment) pressure

0 50000 100000 150000 200000 250000 300000T ime (s)

Pres

sure

(k

Pa)

150

200

250

300

350

400

450

500

550

CVH-P_0701-MELCOR 1.8.6 CVH-P_0701-MELCOR 2.2

N E K SB O

34Containment (upper compartment) temperature

0 50000 100000 150000 200000 250000 300000T ime (s)

Tem

pera

ture

(K

)

340

360

380

400

420

440

460

CVH-TVAP_0701-MELCOR 1.8.6 CVH-TVAP_0701-MELCOR 2.2

N EK SB O

35

MELCOR 1.8.6: Pressurizer pressure, ejected mass to cavity

MELCOR 2.2: Pressurizer pressure, ejected mass to cavity

COR-

MEJ

EC-T

OT_0

000

(kg

)

010

000

2000

030

000

4000

050

000

6000

070

000

8000

0

0 5000 10000 15000 20000 25000 30000T ime (s)

Pres

suriz

er p

ress

ure

(M

Pa)

24

68

1012

1416

CVH-P_0103 A1 COR-MEJEC-TOT_0000 A2

N E K SB O , M EL C O R 1.8.6

COR-

MEJ

EC-T

OT_0

000

(KG

)

010

000

2000

030

000

4000

050

000

6000

070

000

8000

0

0 5000 10000 15000 20000 25000 30000T ime (s)

Pres

suriz

er p

ress

ure

(M

Pa)

24

68

1012

1416

CVH-P_0103 A1 COR-MEJEC-TOT_0000 A2

N E K SB O , M EL C O R 2.2

36

Cavity mass Removed hydrogen by PARs

0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000T ime (s)

Mas

s (

t)

010

2030

4050

6070

8090

100

110

120

CVH-MASS.1_0704-MELCOR 1.8.6 CVH-MASS.1_0704-MELCOR 2.2

N E K SB O

0 50000 100000 150000 200000 250000 300000T ime (s)

Mas

s (

kg)

010

020

030

040

050

060

070

0

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

37

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 4CV 4

CV 5CV 10 CV 6CV 13

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

CV11

CV9

CV12

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

Lowercomp

Reactor pool

ARV

Cavity

Upper compartment cyl

CV 7

FL 35 FL 36

FL 1

FL 11FL 19

FL 12

FL 14

FL 13

PCFV

Containment Failure

TS leak

TS leak

RSumpCSump

Sump pit

Door Failure

FL 38

Cavity Modelling

Cavity Layout and the MCCI

39

Concrete decomposition(at temperatures 873 – 1173 K):CaCO3 → CaO + CO2 (endothermic reaction)

Iron rebar oxidation(600 kg of iron in the 1 m3 of the concrete):Fe + H2O + 3.0 kJ/kg(Fe) → FeO + H2Fe + CO2 + 480 kJ/kg(Fe) → FeO + CO

40

0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 550000 600000T ime (s)

Cont

ainm

ent d

ome

pres

sure

(P

A)

1000

0015

0000

2000

0025

0000

3000

0035

0000

4000

0045

0000

5000

0055

0000

CAV door open ARHR CAV door open Ref CI CAV door closed + 4in hole CAV door closed

SB O - R B C O O L I N G A T 24 H - C I , A R HR , M HX - E S

41

0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 550000 600000T ime (s)

Cont

ainm

ent d

ome

tem

pera

ture

(K

)

340

360

380

400

420

440

460

480

500

520

CAV door open ARHR CAV door open Ref CI CAV door closed + 4in hole CAV door closed

SB O - R B C O O L I N G A T 24 H - C I , A R HR , M HX - E S

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

43

10 0 10 1 10 2 10 3

Time (s)

RCFC

pow

er (k

W)

-18000

-16000

-14000

-12000

-10000

-8000

-6000

-4000

-2000

0

G 7.2b M 1.8.6

10 0 10 1 10 2 10 3

Time (s)

HTC

stee

l lin

er in

side

(W/m

2-K)

0

10

20

30

40

50

60

70

80

90

100

G 7.2b M 1.8.6

10 0 10 1 10 2 10 3

Time (s)

Cont

ainm

ent d

ome

pres

sure

(kPa

)

150

200

250

300

350

400

G 7.2b M 1.8.6

10 0 10 1 10 2 10 3

Time (s)

Cont

ainm

ent d

ome

tem

pera

ture

(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

45

0 100 200 300 400 500 600 700Time (hr)

Activ

ity (M

Ci)

0

10

20

30

40

50

60

70

80

90

100

110

120

N E K C Y C 29 M A A P A ST

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 700Time (hr)

Actv

ity (M

Ci)

0

10

20

30

40

50

60

70

80

90

100


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

47

0 100 200 300 400 500 600 700Time (hr)

Activ

ty (M

Ci)

0

10

20

30

40

50

60

70

80

90


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

www.nek.si, Vrbina 12, 8270 Krško 48

WGB

ST

(KG/

S)

0.5

11.

52

2.5

33.

54

4.5

5

60000 65000 70000 75000 80000 85000 90000 95000 100000 105000 110000 115000 120000T ime (s)

()

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0

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

RE L EA SE C A T E G O RY 8B = SG T R

0 .5 1 1.5 2 2.5 3Time (day)

Leak

age

(%Vc

ont)

0

5

10

15

20

25

30

35

40

45

50N E K SG T R

VOLFLOW_SGTR.dat

0 100 200 300 400 500 600 700Time (h)

Activ

ity (M

Ci)

0

50

100

150

200

250

N E K ES B B 1

Total activity released Activity in environemnt (decay) Activity containment

0 100 200 300 400 500 600 700Time (h)

Activ

ity in

env

ironm

ent +

plu

me

(MCi

)

0

.2

.4

.6

.8

1

1.2

1.4

1.6

N E K ES B B 1

activity_ecr01a_02.dat

RADTRAD and ARCON96 release anddispersion


Time interval ECR/TSC intakeχ/Q (s/m3)

ECR/TSC roofχ/Q (s/m3)

0 – 2 h 2.15E-04 3.09E-042 – 8 h 1.46E-04 2.05E-04

8 – 24 h 6.91E-05 9.90E-051- 4 days 6.71E-05 9.05E-05

4 -30 days 5.18E-05 7.18E-05

RADTRAD compartment model used incalculation


CONTAINMENT COMPARTMENT(ECR) ENVIRONMENT

1 3 2

2

4

1

Leak to environment

Inflow(F2)

Intake F4

Recirculation filterF1

3Exhaust

(F3)

0 100 200 300 400 500 600 700Time (h)

Imm

ersi

on g

amm

a do

se (G

y)

.000

.005

.010

.015

.020

.025

.030

.035

N E K ES SG T R EC R

case01 case02 case03 case04

0 100 200 300 400 500 600 700Time (h)

Gam

m d

ose

(Gy)

.00

.05

.10

.15

.20

.25

.30

.35

.40

.45

.50

.55

B B 1 SG T R ES I m m ersion gam ma 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


10 0 10 1 10 2

Time (h)

Tota

l filt

er a

ctiv

ity (C

i)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

N E K ES SG T R E C R

sum_activity_ecr01d.dat sum_activity_ecr02d.dat sum_activity_ecr03d.dat sum_activity_ecr04d.dat

0 100 200 300 400 500 600 700Time (h)

Gam

ma

dose

(Gy)

0

10

20

30

40

50

60

70

80

90

100

110

120

B B 1 M R dose from f ilter 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)


0 100 200 300 400 500 600 700Time (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 700Time (h)

Dose

(Gy)

0

2

4

6

8

10

12

14

16

18


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 10 0 10 1 10 2

Time (h)

Conc

entra

tion

(Bq/

m3)

10 0

10 1

10 2

10 3

10 4

10 5

10 6

10 7


external_ecr01d_200m_conc_Bq_m3 external_ecr01d_500m_conc_Bq_m3 external_ecr01d_xq_500m_conc_Bq_m3

53

0 100 200 300 400 500 600 700Time (h)

Filte

r act

ivity

(Ci)

0

10

20

30

40

50

60


filter_activity_ecr01d_Cs-134.dat filter_activity_ecr01d_Cs-136.dat filter_activity_ecr01d_Cs-137.dat

54

0 100 200 300 400 500 600 700Time (h)

Filte

r act

ivity

(Ci)

0

20

40

60

80

100

120

140

160

180

200


filter_activity_ecr01d_I-131.dat filter_activity_ecr01d_I-132.dat filter_activity_ecr01d_I-133.dat filter_activity_ecr01d_I-134.dat filter_activity_ecr01d_I-135.dat

55

10 0 10 1 10 2

Time (h)

Fite

r act

ivity

(Ci)

0

100

200

300

400

500

600

700

800

900

1000

1100


activity_ecr01d_f01.dat activity_ecr01d_f04.dat activity_ecr02d_f01.dat activity_ecr02d_f04.dat activity_ecr03d_f01.dat activity_ecr03d_f04.dat activity_ecr04d_f01.dat activity_ecr04d_f04.dat

NEK AB• NEK Equipment Survivability for DEC• model similiar to the model developed in GOTHIC• AB model has 115 control volumes, 202 flow paths and 510 heat

structures, control functions are used for door opening on pressure difference

56

SBO accident – Temperatures in AB

0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 550000 600000Time (s)

Tem

pera

ture

(C)

40

42

44

46

48

50

52

54

56

58

60

N EK SB O ES A B

AB014 AB015 AB045 AB055 AB093 AB094

57

SBO accident – H2 concentration in AB

0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 550000 600000Time (s)

H2 v

ol fr

actio

n

.00000

.00005

.00010

.00015

.00020

.00025

.00030

.00035

N EK SB O ES A B

AB014 AB015 AB045 AB055 AB093 AB094 AB098

58

NEK SFP calculationNEK SFP between two cycles 9 days after shutdown

FAs 9 - 12150 days old

POWER POWER SPAN TOTAL

OLD 98 W – 52.82 kW 5.71 MW

NEW 89 W – 2.03 kW 0.573 MW

TOTAL 6.283 MW

59

Time to boiling (h) vs. Decay heat (MW) for different scenarios

60

0 1 2 3 4 5 6 7 8 9

20

40

60

80

100

120

140

160

180

200

220

240

N EK SFP

c1 c2 c3 c4

Elevation of water in pool (m) vs. time (h) for different scenarios and different level of decay heat (MW)

61

0 100 200 300 400 500 600 700 800 900103

104

105

106

107

108

109

110

111

112

113

114

115N EK SFP

c1_H_1.5 c1_H_6.0 c1_H_8.5 c2_H_1.5 c2_H_6.0 c2_H_8.5 c3_H_1.5 c3_H_6.0 c3_H_8.5 c4_H_1.5 c4_H_6.0 c4_H_8.5

NEK SFP (3)

FHB

SFP

62

FHB model

63

0 100000 200000 300000 400000 500000 600000Vrijeme (s)

Tlak

(kPa

)

101.20

101.22

101.24

101.26

101.28

101.30

101.32

101.34

N E K FHB gubitak hladjenja SFP (6.28 M W )

fhb06hs2__PR21s1.dat fhb06hs2__PR21s2.dat

0 100000 200000 300000 400000 500000 600000Vrijeme (s)

Mas

eni p

roto

k kr

oz p

anel

(kg/

s)

0

1

2

3

4

5

6

7

8

N EK FHB gubitak hladjenja SFP

fhb06hs2_FV45.dat 0.575 m2 fhb06hs2_FV45.dat 1.15 m2

SFP GOTHIC models

SFP model - detailedSFP model - simple

64

SFP GOTHIC calculation

150000 200000 250000 300000 350000 400000 450000 500000 550000Time (s)

Wat

er le

vel (

m)

104

104.5

105

105.5

106

106.5

107

N EK SFP

simple old simple new detailed old high detailed old low

65

MELCOR SFP model

110RING 1

120RING 2

210 BYPASS

1

220BYPASS

2

300ABOVE RACKS

100INLET

299DOWNCOMER

301ABOVE DC

900ENVIRONMENT

900ENV

210

220

110

120

211

111

221

121

307306

699

320

321

66

Without spray - 1 cm2 break

0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 550000 600000T I M E_0000 (S)

Tem

pera

ture

(K

)

400

600

800

1000

1200

1400

1600COR-TCL_0104 A1 COR-TCL_0105 A1 COR-TCL_0106 A1 COR-TCL_0107 A1 COR-TCL_0108 A1 COR-TCL_0109 A1 COR-TCL_0110 A1 COR-TCL_0111 A1 COR-TCL_0112 A1

SFP Separ/ 7/13/17 /17:45:20 /SFPR5PLOT FER v2.4m

20:09:13, 13/07/2017

67

Without and with spray - 1 cm2 break

0 50000 100000 150000 200000 250000 300000 350000 400000 450000 500000 550000 600000T ime (s)

Leve

l (M

)

1

2

3

4

5

6

7

8

9

10

11CVH-CLIQLEV_0100 A CVH-CLIQLEV_0110 A CVH-CLIQLEV_0300 A CVH-CLIQLEV_0100 B CVH-CLIQLEV_0110 B CVH-CLIQLEV_0300 B

N E K SFP M elcor

68

Documents

FER MELCOR Activities - Paul Scherrer Institute · FER MELCOR Activities. The 10th Meeting of the „European MELCOR User Group”, Zagreb, Croatia, 25–27 April, 2018 Content: