MELCOR Validation against Experiments on Hydrogen Distribution

MELCOR Validation MELCOR Validation

againstagainst

Experiments on Experiments on

Hydrogen DistributionHydrogen DistributionJiri Duspiva

Nuclear Research Institute Rež, plc.Nuclear Safety and Reliability Division

Dept. of Severe Accidents and Thermomechanics

3rd European MELCOR User Group MeetingBologna, Italy, April 11-12, 2011

J. Duspiva 3rd EMUG Bologna, Italy, April 11-12, 2011

2

Outline

OECD THAI HM2 Test Definition

MELCOR Model Development

MELCOR Simulations• Sensitivity Cases

Conclusions


3

OECD THAI HM2 Test

HM test series objectives• Investigation of transferability of the experimental

results performed with simulator – helium on hydrogen cases

• Phenomenological objective of the HM tests was to investigate conditions for the hydrogen rich cloud erosion by steam and break up a light gas stratification

HM2 test conduct • Filling of facility by nitrogen

• Hydrogen injection – formation of light gas cloud

• Steam injection• Steam plum stagnation inside of cylindrical structure

• Erosion of light gas cloud – natural circulation

• Atmosphere homogenization


4

OECD THAI HM2 Test

Main Phases• Time < 0 s Filling with nitrogen

• 0 – 4200 s H2 injection

• 4320 – 6820 s Steam injection – cloud erosion

• Time > 6820 s Steam inj. - Atm. homogenization

(2)


5


Overview of improved (Open) model (comp. with original (Blind) one)

Only for MELCOR 1.8.6 due to absence of Film tracking networks• Too complicated system of HSs

Modification of parameter XMTFCi - enhanced scaling constant of mass transfer in the condensation correlation - HSnnnnn400 (9)• Inner surface of inner cylindrical structure – resulted in possibility to

model stagnation phase and agreement of pressure evolution in this phase

• Inner surface of TTV – agreement of pressure evolution in phase of natural convection

New screen for ATLAS prepared Model was converted to MELCOR 2.1 – possibility of FT and SPR


6


Blind

Open

Comparison of Nodalizations

Ax.L. 02

Ax.L. 03

Ax.L. 04

Ax.L. 05

Ax.L. 06

Ax.L. 07

Ax.L. 09

Ax.L. 10

Ax.L. 11

Ax.L. 12

Ax.L. 13

Ax.L. 14

Ax.L. 15

Ax.L. 01

Ax.L. 08

CV020

CV110

CV150

CV210

CV310

CV010

CV350

CV410

CV510

CV250

CV550

CV610

CV650

CV740

CV450

4.000 m

5.125 m

6.595 m

3.080 m

6.920 m

7.570 m

7.895 m

8.220 m

8.800 m

9.200 m 9.755 m

5.875 m

0.320 m

1.240 m

1.770 m

2.155 m

0.000 m

2.300 m

Ax.L. 17

Ax.L. 18

Ax.L. 19

Ax.L. 20

Ax.L. 21

Ax.L. 22

Ax.L. 23

Ax.L. 16

CV770

CV810

CV840

CV870

CV910

CV940

CV980

CV710

8.510 m

7.245 m

5.500 m

4.750 m

4.375 m

3.540 m

6.245 m

2.620 m

0.375 m

0.375 m

0.325 m

0.325 m

0.325 m

0.325 m

0.290 m

0.955 m

0.370 m

0.290 m

0.325 m

0.375 m

0.375 m

0.375 m

0.460 m

0.350 m

0.460 m

0.465 m

0.385 m

0.530 m

0.920 m

0.320 m

0.460 m

Altitude Node Height

CV110

CV010

CV 111

CV 021

CV11i

HS11i01

HS02101

HS02104 HS0211i

HS01003

HS01002

HS01001

HS02102

HS02103

FL020 FL021

FL010 FL011

FL10i

FL022

CV990

FL11i FL101

HS87k01

HS84k01

HS81k01

HS74k03 HS74k02 HS74k01

HS71k01

HS65k01

HS31i01

HS91k02

HS21i01

HS15i02

HS15i01

HS11i02

HS45k01

2.600 m

8.200 m

5.400 m

CV993

CV992

CV991

HS98003 HS98002

HS98001

HS94k01 FL921

FL951 FL950

CV 741

CV74k FL731 FL73k

FL721 FL720 FL74k

FL72k CV 711

CV71k FL701 FL70k

FL661 FL660 FL71k

FL66k

CV 811

CV81k FL801 FL80k

FL781 FL780 FL81k

FL78k

CV 841

CV84k FL831 FL83k

FL821 FL820 FL84k

FL82k

CV 871

CV87k FL861 FL86k

FL851 FL850 FL87k

FL85k

CV 911

CV91k FL901 FL90k

FL881 FL880 FL91k

FL88k

CV 651

CV65k FL641

FL621 FL620 FL65k

FL62k

CV 611

CV61k FL601

FL561 FL560 FL61k

FL56k

CV 551

CV55k FL541

FL521 FL520 FL55k

FL52k

CV 511

CV51k FL501

FL461 FL460 FL51k

FL46k

CV 451

CV45k FL441

FL421 FL420 FL45k FL42i

CV 411

CV41i FL401

FL361 FL360 FL41i FL36i

CV 351

CV35i FL341


CV 771

CV77k FL761 FL76k

FL751 FL750 FL77k

FL75k

CV 211

CV21i FL201

FL161 FL160 FL21i

FL16i

CV 251

CV25i FL241


CV 311

CV31i FL301


CV 151

CV15i FL141 FL14i

FL121 FL120 FL15i

FL12i

CV 941 CV94k FL920

FL92k

HS6511k

HS6510k

HS6110k

HS5510k

HS5110k

HS4510k

HS4110i

HS3510i

HS3110i

HS2110i

HS2510i

HS1511i HS1512i

HS11101

HS15101

FL93k FL931

FL94k

HS91k03

HS91k01

HS77k01

HS55k01

HS51k01

HS41i01

HS35i01

HS61k01

HS25i01

HS98004

HS35k02

FL559

FL619

FL659

FL719

FL749

FL779

FL819

FL849

FL879

FL919

FL519 FL529

FL569

FL629

FL669

FL729

FL759

FL789

FL829

FL859

FL889

FL929

FL980

CV879

CV849

CV819

CV779

CV749

CV719

CV659

CV619

CV559

CV519

CV919

FL599

FL539

FL499

FL439

FL399

FL138

FL139

CV149

CV249

CV309

CV349

CV409

CV509

CV209

CV549

CV609

CV449

FL199

FL239

FL299

FL540

FL500

FL440

FL400

FL300

FL600

FL240

FL200

FL140

FL340

FL339

Ax.L. 02

Ax.L. 03

Ax.L. 04

Ax.L. 05

Ax.L. 06

Ax.L. 07

Ax.L. 09

Ax.L. 10

Ax.L. 11

Ax.L. 12

Ax.L. 13

Ax.L. 14

Ax.L. 15

Ax.L. 01

Ax.L. 08

CV020

CV110

CV150

CV210

CV310

CV010

CV350

CV410

CV510

CV250

CV550

CV610

CV650

CV710

CV450

CV 651

CV 611

CV 551

CV 511

CV 451

CV 411

CV 351

CV 311

CV 251

CV 211

CV 151

CV 111

CV 021

CV61i

CV55i

CV51i

CV45i

CV41i

CV31i

CV65i

CV25i

CV15i

CV35i

CV11i

CV21i

HS71004 HS71003 HS71002

HS71001

HS65i02

HS65i01

HS61i01

HS55i01

HS51i01

HS45i02

HS45i01 HS41i02

HS41i01

HS35i01

HS25i01

HS61i02

HS21i01

HS15i02

HS15i01

HS11i02

HS11i01

HS31i01

HS02101

HS02104

HS11101

HS15101 HS1511i HS1512i

HS2110i

HS2510i

HS0211i

HS3110i

HS3510i

HS3511i

HS01003

HS01002

HS01001

HS02102

HS02103

HS25j02

FL020

FL120

FL160

FL220

FL260

FL021

FL010

FL121

FL161

FL221

FL261

FL12i

FL16i

FL011

FL22i

FL26k

FL101

FL141

FL201

FL241

FL341

FL10i

FL14i

FL022

FL44i FL441

FL501

FL541

FL601

FL641

FL320

FL301

FL401

FL50i

FL54i

FL60i

FL64i

FL321

FL40i

FL421

FL461

FL521

FL561

FL621

FL661

FL420

FL361

FL460

FL520

FL560

FL620

FL660

FL42i

FL360

FL46i

FL52i

FL56i FL62i

FL36i

FL32i

FL31i

FL21i

FL15i

FL11i

FL41i

FL35i

FL45i

FL51i

FL55i

FL61i

FL65i

FL35i

0.320 m

1.240 m

1.770 m

2.155 m

4.000 m

0.000 m

5.100 m

6.600 m

3.100 m

7.000 m

7.400 m

7.800 m

8.220 m

8.200 m

9.200 m 9.755 m

6.245 m

2.300 m

2.600 m

8.200 m

5.400 m

CV903

CV900

CV902

CV901


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Radial Discretisation

CV111

CV118

CV119 CV112

CV113

CV114

CV115

CV116

CV117

CV110

FL122 FL123

FL124

FL125 FL126

FL127

FL128

FL129

FL120 FL121

FL102

FL103

FL104

FL105 FL106

FL107

FL108

FL109

FL101 FL118

FL119 FL112

FL113

FL114 FL115 FL116

FL117

0°

180°

90° 270°

60°

30°

120°

150° 210°

240°

300°

330°

CV811

CV818

CV812

CV814

CV816

CV810

FL822

FL824

FL826

FL828 FL820 FL821

FL802

FL804

FL806

FL808 FL801

FL818

FL812

FL814 FL816

0°

180°

90° 270°

60°

30°

120°

150° 210°

240°

300°

330°

Radial discretisation• Blind simulation

• Levels 03 – 14 (8 azimuthal nodes)

• Open simulation• Levels 03 – 09 (8 azimuthal nodes)• Levels 10 – 22 simplified periphery (4 azimuthal nodes instead of 8 in lower part)

Ratio of flow areas of inside volume of cylindrical structure• 52.5 % to 47.5 % (R 0.500 m)


8

Modification of parameter XMTFCi Modification of parameter

XMTFCi – values used in final simulation

•XMTFCL = 2.00

•XMTFCL = 3.02

•XMTFCL = 4.00

•XMTFCR = 5.00

MELCOR Model – Open Simul.


9

MELCOR 1.8.6 Final Simulation

Comparison of Blind Open

H2 Concentration – End of Injection


10

Significant improvement of Open simulation in comparison with Blind simulation

•Duration of stagnation phase

•Timing of cloud dissolution

Pressure and H2 Concentration

MELCOR 1.8.6 Final Simulation

DOME

I NNER CYLI ND.

ANNULUS

SUMP

LOWER HEAD

Hydrogen injection Steam injection

Stagnation

Hydrogen cloud erosion

DOME

I NNER CYLI ND.

ANNULUS

SUMP

LOWER HEAD


Stagnation


DOME

I NNER CYLI ND.

ANNULUS

SUMP

LOWER HEAD

Hydrogen injection

Steam injection

Stagnation



11

M1.8.6 to M2.1 Comparison

Practically identical results of M186 and M2.1 with identical inputs

•Results of simulation with M186 are visualized using ATLAS

Pressure and H2 Concentration

DOME

I NNER CYLI ND.

ANNULUS

SUMP

LOWER HEAD


Stagnation


DOME

I NNER CYLI ND.

ANNULUS

SUMP

LOWER HEAD


Stagnation


DOME

I NNER CYLI ND.

ANNULUS

SUMP

LOWER HEAD


Stagnation



12

M186 and M2.1 Simulations

Observations from input conversion

• HSs in M2.1 input have to be in order of condensate drainage (starting from top to bottom of drainage HS chain)

• Each of HSs has to have a definition of drainage, including the last one which is drained into pool of associated CV

Cases compared• M186noFT– no film tracking

model + no spraying by condensate

• M21noFT – no film tracking model + no spraying by condensate

• M21yFT – film tracking model + no spraying by condensate

• M21yFTSPR – film tracking model + spraying by condensate

Very similar results of all cases

• All cases have identical definition of XMTFCi parameters

Impact of FT and SPR(1)


13

M186 and M2.1 Simulations

Cases compared• M186noFT– no film tracking

model + no spraying by condensate

• M21noFT – no film tracking model + no spraying by condensate

• M21yFT – film tracking model + no spraying by condensate

• M21yFTSPR – film tracking model + spraying by condensate

Very similar results of all cases• Neglect of FT and SPR definition in

M186 did not influenced predicted results significantly

• Confirmation of assumption from blind simulation

• Practically identical results of M186noFT and M21noFT

• Spraying of ATM by condensate has negligible impact

• Slightly higher pressure, probably due to different ATM flow pattern (ATLAS cannot be applied for post-processing in M2.1)

• Film tracking seems be a little more important in this exercise

Impact of FP and SPR(2)


14

M186 Simulations

Very similar results of all cases

• All cases have identical definition of XMTFCi parameters

• What is effect of RN Package?

Cases compared (all M186)• noRNyX – noRN+DCH + XMTFCi• noRNnoX – noRN+DCH +

noXMTFCi • yRNyX – RN+DCH + XMTFCi• yRNnoX – RN+DCH + noXMTFCi

Results differ mainly based on application of XMTFCi

• Neglectable impact of RN + DCH application to steam mass in TTV

• Some impact on fog mass, but no influence of pressure

• It only influence distribution of condensate among aerosols (fog) and on wall (HS)

Impact of RN Package


15

M186 SimulationsImpact of Max. Fog Density

ISP-47 test included measurement of fog density

• Max measured value < 40g/m3, but M default is 100g/m3

• What is effect of FD? Cases compared (all M186)

• Open-XMT – 100g/m3 + XMTFCi• Open-noXMT – 100g/m3 +

noXMTFCi • FD-XMT – 30g/m3 + XMTFCi• FD-noXMT – 30g/m3 + noXMTFCi

Results differ mainly during cloud erosion phase

• Fog density limit influence total density of ATM influence of hydrostatic head (steam jet has greater buoyant forces)

• Lower FD limit results in lighter ATM more intensive penetration of buoyant plume into H2 rich cloud

• Earlier cloud dissolution

• Comparable impact of XMTFCi and FD on timing of cloud dissolution, but not on pressure


16

M186 SimulationsImpact of Re Limits in Film on HS

SC4253 (5) and (6) define limits of Re for film on HS

• Inconsistency between literature and UG found by T. Sevon (VTT) – see contribution to CSARP 2010 SC4253(5) new value 30.0 SC4253(6) new value 1800.0

Cases compared (all M186)• Open-XMT – final simulation with

XMTFCi• Open-noXMT-SC4253 – noXMTFCi +

modified SC4253• Open-noXMT-SC4253-CLNi –

noXMTFCi + modified SC4253 + modified charact. dimensions of HS (inner surfaces)

• RN-FD-noXMT-SC4253-CLNi – RN pack. + reduced fog density + noXMTFCi + modified SC4253 + modified charact. dimensions of HS (inner surfaces)

Results differ mainly during cloud erosion phase

• Cases 2 and 3 has high mass of steam and fog high pressure and too slow cloud erosion

• Case 4 has high mass of steam but low fog and case 1 has low steam and high fog correct timing of cloud erosion


17

Summary and Conclusions

Application of MELCOR confirmed possibility to predict THAI HM2 test correctly if• Appropriate nodalization scheme used to model

• Hydrogen stratification – axial discretisation very important

• Hydrogen cloud erosion by steam

• Knowledge of facility, experimental conditions, and code• Need to enhance steam condensation for successful prediction of pressure

evolution and flow regimes in facility• Under laminar or transition natural convection conditions

• Modeling of H2 and steam jet CVs seems to be needed, although its replacement by movement source location predicted relatively acceptable hydrogen distribution, but it results in temporary deviations

• Immediate start of hydrogen presence in case with moved source location vers. delayed hydrogen presence in case with jet CVs

• Model with jet CVs predicted better agreement in

• H2 distribution in lower levels and timing of phases

Identification of condensate spraying model malfunction in M186 YT• BUG Report No. 172 (April 2008) – solved in M186 YU


18

Acknowledgments

The effort included in this paper was performed with the support of the CR Ministry of Industry and Trade project, and the partnership in the OECD THAI project is funded by the CR Ministry of Education, Youth, and Sports.

Author acknowledges partners in the OECD THAI project for their approval of this contribution


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End of Presentation

Documents

MELCOR Validation against Experiments on Hydrogen Distribution