KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

Institute of Neutron Physics and Reactor Technology (INR)

www.kit.edu

Ex-vessel LOCA for the European HCPB TBM system using the pedigreed MELCOR182 for fusion

X. Jina, B. Merrillb, L. V. Boccaccinia

The 4th Meeting of the “European MELCOR User Group”

Cologne , Germany

April 16-17, 2012

a Karlsruhe Institute of Technology (KIT)b Idaho National Laboratory (INL)

Institute of Neutron Physics and Reactor Technology (INR)

2 4th EMUG X. Jin

Outline

Pedigreed MELCOR182 for fusion

HCPB TBM and HCS

Ex-vessel LOCA

Accidental sequence

MELCOR model for helium blow-down

MELCOR 3D-model for ½ BU

MELCOR results & open issues

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3 4th EMUG X. Jin

Pedigreed MELCOR182 for fusion

* Merrill B.J., Modifications to the MELCOR code for application in fusion accident analyses, Fusion Engineering and Design 51-52, 2000.

The version is modified by INL for ITER purposes*:

chemical oxidation reactions of steam with Be, C and W,

extension of water properties below its triple point temperature for Loss Of Coolant Accidents (LOCAs) into cryostats,

the cryogenic He or air as the primary fluid,

convective boiling,

HTO transport,

enclosure radiant heat transfer.

In 2010 input deck limited to 9999 lines were extended, but the limitation for CV, FL, CF and TF (999) is not changed.

Institute of Neutron Physics and Reactor Technology (INR)

4 4th EMUG X. Jin

HCPB TBM and the combined HCSVertical TBM box

Breeder Unit (BU)

HCS and results at steady state (RELAP5-3D)

Ex-vessel LOCA is assumed at the steady stateHCPB: Helium Cooled Pebble Bed FW: First Wall TBM: Test Blanket Module BU: Breeder UnitHCS: He Cooling System MF: ManifoldPCS: Pressure Control System MX: Mixer

Institute of Neutron Physics and Reactor Technology (INR)

5 4th EMUG X. Jin

Accidental sequence

HCPB TBM & HCS(Steady state)

Ex-vessel LOCAinside port cell

Helium blow-down(HCPB TBM & HCS)

Active plasma shutdown

fast plasma shutdown

(3s)

yes

yes Be-steam reaction(TBM box)

Failures of ITER FW & TBM FW

yes

no

T behavior

T behavior & H2 production

RELAP5-3D

MELCOR

MELCOR

ANSYS

Plasma disruption(1s)

ANSYS 3D-model of the TBM with ¼ BU

CTmolKJHBeOOHBe 300,/37022 ANSYS-temperatures after the plasma disruption are MELCOR initial temperatures.

470490510530550570590610630650670690710730750770

0 25 50 75 100

125

150

175

200

225

250

275

300

325

350

time (s)

Tem

pera

ture

(°C

)

FW

ANSYS calculation

Institute of Neutron Physics and Reactor Technology (INR)

6 4th EMUG X. Jin

Helium blow-down inside port cell

MELCOR nodalization for the HCS and HCPB TBM

Location of the port cell & HCPB TBM *

* Boccaccini L.V. et al., Present status of the conceptual design of the EU test blanket systems, Fusion Engineering and Design 86(2011) 478-483.

CVCS: Chemical and Volume Control Systems

Institute of Neutron Physics and Reactor Technology (INR)

7 4th EMUG X. Jin

Pressure behavior inside port cell & pressure drop of the system

9.950E+04

1.112E+05

1.229E+05

1.346E+05

1.463E+05

1.580E+05

1.697E+05

1.814E+05

1.931E+05

2.048E+05

2.165E+05

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

time (s)

Pre

ssur

e (P

a)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

port cell, with VDSport cell, no VDSITER limitpressure drop (%)

MELCOR nodalization for the VDS

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Beryllium–steam reaction in the long term

VVPSS: Vacuum Vessel Pressure Suppression System

MELCOR modelling for failures of ITER FW & TBM FW

(1.57E-3m²) (2.7E-3m²)

(1.2963E-3 m²)

Institute of Neutron Physics and Reactor Technology (INR)

9 4th EMUG X. Jin

MELCOR 3D-model for ½ BU

190

402

29.5 5

61

22

EUROFER

BERYLLIUM

Li4SiO4

R45R25

151

CVjiki=5

152 153 154 155 156

251 252

351 353 354 355 356

FW

25

BU

ada

pter

335

HG18010050

25

rad (k)

pol (j)

cap

VG

HG

206.5

6

113

CVjikk=3

123 133 143 153 163 173 183 193

213 293

313 323 333 343 353 363 373 383 393

194.5

tor (i)

pol (j) 12 24 40 42.5

• modeling for 1 pebble d1peb = 1 mm, HSMULT = Npeb.

• thermal conduction between adjacent cells by modeling the heat conducted from one cell to be received by a HS in the adjacent cell in the given direction.

• internal power source: decay heat as table function ~ time.

• radiation: gray-gas-a, emissivity 0.65.

Cells: 3x9x6 = 162

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VV135°C, 1 Pa

1090 m³CV401

FL405

Water source(FW/BLK)

135°C, 3 MPa,140m³, CV403

FL403

VVPSS

HCPB TBM HCS

VDS

FW 1 6 pipesCV720

Be pebCV351

VVp & T

CV401½ BU

FL401

FL402

p & T of the VV ~ time(ICVAT=-2)

Failure of TBM FW to the beryllium pebble bed

Failures of ITER FW & TBM FW to the VV

(1.57E-3m²)

(2.7E-3m²)

(1.2963E-3 m² / 2)

MELCOR simulations

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11 4th EMUG X. Jin

MELCOR results in the long term

Temperature behavior and H2 production

t = 6.335626E+02 DT(CVH) = 1.241800E-05CPU = 1.469860E+07 = 170 days

0.0E+00

2.0E+04

4.0E+04

6.0E+04

8.0E+04

1.0E+05

1.2E+05

1.4E+05

1.6E+050

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

time (s)

Pre

ssur

e (P

a)

30

50

70

90

110

130

150

170

190

Tem

pera

ture

(°C

)

total pp_steamT

Pressure and temperature behavior in the VV

0.0E+00

5.0E-06

1.0E-05

1.5E-05

2.0E-05

2.5E-05

3.0E-05

0 40 80 120

160

200

240

280

320

360

400

440

480

520

560

600

640

680

time (s)

Mas

s (K

g)

440

465

490

515

540

565

590

Tem

pera

ture

(°C

)

CVH-TOT-M.4CVH-TVAP_351

H2 -results for the first 400s are shown in [1] Jin X., Merrill B.J., Boccaccini L.V., Preliminary safety analysis of ex- vessel LOCA for the European HCPB TBM system, Fusion Engineering and Design, in press.

Institute of Neutron Physics and Reactor Technology (INR)

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Open issues

Helium is treated as noncondensible gas.

CVH-TOT-M.4 cannot show the total H2 production of the system because p&T of the VV are specialized as a function of time.

Round-off error due to the single precision of the version 1.8.2

limitation for CV, FL, CF and TF (999).

Updated MELCOR version for fusion is needed !

Foliennummer 1OutlinePedigreed MELCOR182 for fusionHCPB TBM and the combined HCSAccidental sequenceHelium blow-down inside port cell Foliennummer 7Beryllium–steam reaction in the long term MELCOR 3D-model for ½ BUMELCOR simulationsMELCOR results in the long termOpen issues