Development of a RELAP5-3D Development of a RELAP5-3D thermal-hydraulic model for a thermal-hydraulic model for a

Gas Cooled Fast Reactor Gas Cooled Fast Reactor

D. Castelliti, D. Castelliti, C. ParisiC. Parisi, G. M. Galassi, N. Cerullo, G. M. Galassi, N. Cerullo (San Piero A Grado Nuclear Research Group )

DIMNP – University of Pisa - ITALY

2006 RELAP5-3D© Users Seminar Holiday Inn SunSpree Resort – West Yellowstone – USA

16 – 18 August 2006

ContentsContents

• IntroductionIntroduction

• ETDR Thermal-Hydraulic NodalizationETDR Thermal-Hydraulic Nodalization

• Main ResultsMain Results Steady State Steady State TransientTransient

• ConclusionsConclusions

Introduction [1/3]Introduction [1/3]

• GCFRGCFR, , a Gen IV system developed by a Gen IV system developed by a wide international consortium (NNC, a wide international consortium (NNC, CEA, CIRTEN, Framatome, JRC-IE, CEA, CIRTEN, Framatome, JRC-IE, NRG, PSI, Univ. of Delft, etc.)NRG, PSI, Univ. of Delft, etc.)

• Huge efforts required for testing Huge efforts required for testing materials, component, plants layoutmaterials, component, plants layout

• Need to have a testing facility Need to have a testing facility ETDR ETDR

• Need to have Need to have numerical toolnumerical tool and a and a modelmodel for proposed experimental for proposed experimental analysesanalyses

Introduction [2/3]Introduction [2/3]

• Different features of GCFR system Different features of GCFR system vs.vs. present NPPs present NPPs technologytechnology Helium coolantHelium coolant Direct Brayton cycleDirect Brayton cycle Fast Neutron FluxFast Neutron Flux Fuel geometryFuel geometry

Needs to have a reliablereliable

and flexibleflexible system code

for experiments planning and analyses

RELAP5-3DRELAP5-3D©©

Introduction [3/3]Introduction [3/3]

• Proposed ETDR layout as testing facility for GCFR system:Proposed ETDR layout as testing facility for GCFR system:

Testing Testing start-up start-up and and demodemo corescores (different temperatures ranges) (different temperatures ranges) Testing fuel and structural materialsTesting fuel and structural materials Analyzing system dynamic behaviorAnalyzing system dynamic behavior Asses Codes QualificationAsses Codes Qualification

AIRC~51 MWth~41 MWth

AHX1-2-31,5 MWth

ETDR CORES(starting and demo)

MC

HeHeH2O

MHX~51 MWth~41 MWth

HeDHR loops

MP

H2O

IHX "HTTR"

0 MWth~10 MWth

to possibly test hight

temperature processes or components

AIR

50 MWth100 MW/m3

MC

AC

AC

Main Cooling SystemPrimary Helium Secondary pressurized water Air Cooler

Circuit reservation

ETDR TH Nodalization [1/2]ETDR TH Nodalization [1/2]

100

102

104

200

340

350360

500

240

600

250

450

480

290

410

110 111120 140

650

220

550

304

312

320

328

400

300

308

316

324

332

700 760

720 740

730

460

800

810

820

840

880

885

960

900940

916

920

910

912

980

990

999

• 722722 Nodes• 836836 Junctions• 401401 Heat Structures • 46354635 Mesh Points

AIRC~51 MWth~41 MWth

AHX1-2-31,5 MWth

ETDR CORES(starting and demo)

MC

HeHeH2O

MHX~51 MWth~41 MWth

HeDHR loops

MP

H2O

IHX "HTTR"

0 MWth~10 MWth

to possibly test hight

temperature processes or components

AIR

50 MWth100 MW/m3

MC

AC

AC

Main Cooling SystemPrimary Helium Secondary pressurized water Air Cooler

Circuit reservation

ETDR TH Nodalization [2/2]ETDR TH Nodalization [2/2]

• Core modeled by two hydraulic channelsCore modeled by two hydraulic channels Average channelAverage channel Hot channelHot channel

• MULTID component used for MHX for an improved MULTID component used for MHX for an improved estimation of Heat Transfer Coefficient (HTC estimation of Heat Transfer Coefficient (HTC notnot imposed)imposed)

• Blower modeled by PUMP componentBlower modeled by PUMP component use of use of benchmark homologous curvesbenchmark homologous curves

• Heat structures simulated for all componentsHeat structures simulated for all components

• Model qualified according to benchmark dataModel qualified according to benchmark data

Qualification [1/2] - Volume-Height CurveQualification [1/2] - Volume-Height Curve

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 5 10 15 20 25

Height (m)

Plant

Nodalization

Qualification [2/2] - Steady State ResultsQualification [2/2] - Steady State ResultsParameterParameter ValueValue ReferenceReference ErrorError

System flow rateSystem flow rate 32.1832.18 Kg/s Kg/s 32.0032.00 Kg/sKg/s 0.56 %0.56 %

Average channel flow rateAverage channel flow rate 0.600.60 Kg/s Kg/s N/AN/A N/AN/A

Hot channel flow rateHot channel flow rate 0.580.58 Kg/s Kg/s N/AN/A N/AN/A

Pressure (top of the vessel)Pressure (top of the vessel) 6.926.92 MPa MPa 7.007.00 MPa MPa 1.14 %1.14 %

Total mass of coolantTotal mass of coolant 450.28450.28 Kg Kg N/AN/A N/AN/A

Total mass of coolant without DHRTotal mass of coolant without DHR 351.60351.60 Kg Kg N/AN/A N/AN/A

Core inlet temperatureCore inlet temperature 262.5262.5 °C °C 260.0260.0 °C °C 0.96 %0.96 %

Core average exit temperatureCore average exit temperature 561.7561.7 °C °C 560.0560.0 °C °C 0.30 %0.30 %

Exit temp. In average channelExit temp. In average channel 560.6560.6 °C °C N/AN/A N/AN/A

Exit temp. In hot channelExit temp. In hot channel 613.2613.2 °C °C N/AN/A N/AN/A

Maximum clad temp. In avg. channelMaximum clad temp. In avg. channel 623.0623.0 °C °C N/AN/A N/AN/A

Maximum clad temp. In hot channelMaximum clad temp. In hot channel 685.0685.0 °C °C N/AN/A N/AN/A

Maximum fuel temp. In avg. channelMaximum fuel temp. In avg. channel 944.0944.0 °C °C N/AN/A N/AN/A

Maximum fuel temp. In hot channelMaximum fuel temp. In hot channel 1067.01067.0 °C °C N/AN/A N/AN/A

Main blower headMain blower head 83998399 m m22/s/s22 8565 m8565 m22/s/s22 1.94 %1.94 %

Main blower torqueMain blower torque -2025.5-2025.5 Nm Nm -2036.4 Nm-2036.4 Nm 0.53 %0.53 %

Main heat exchanger heat transfer areaMain heat exchanger heat transfer area 157.32157.32 m m22 157.00157.00 m m22 0.2 %0.2 %

Main heat exchanger heat transfer coefficientMain heat exchanger heat transfer coefficient 2261.82261.8 W/(m W/(m22 K) K) 1648.0 1648.0 W/(mW/(m22 K) K) 37.2 %37.2 %

Reactor powerReactor power 50 MW50 MW 50 MW50 MW 00 % %

Core pressure dropCore pressure drop -0.42-0.42 bar bar -0.41-0.41 bar bar 2.44 %2.44 %

Main blower pressure dropMain blower pressure drop 0.51470.5147 bar bar N/AN/A N/AN/A

LOFA Results [1/7] - Blower VelocityLOFA Results [1/7] - Blower Velocity

0

100

200

300

400

500

600

0 500 1000 1500 2000 2500 3000 3500

Time (s)

Vel

ocity

(rad

/s)

Run-down provided

Run-down calculated

LOFA Results [2/7] - Primary pressureLOFA Results [2/7] - Primary pressure

5.8

6

6.2

6.4

6.6

6.8

7

7.2

0 500 1000 1500 2000 2500 3000 3500

Time (s)

Pres

sure

(MPa

)

Run-down provided

Run-down calculated

LOFA Results [3/7] - DHR mass flow - helium sideLOFA Results [3/7] - DHR mass flow - helium side

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 500 1000 1500 2000 2500 3000 3500

Time (s)

Mas

s Fl

ow (

Kg/

s)

Run-down provided

Run-down calculated

Open DHR valves

LOFA Results [4/7] – DHR mass flow – water sideLOFA Results [4/7] – DHR mass flow – water side

-10.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

0 500 1000 1500 2000 2500 3000 3500

Time (s)

Ma

ss

Flo

w (

Kg

/s)

Run-down provided

Run-down calculated

LOFA Results [5/7] - Hot channel Clad temperatureLOFA Results [5/7] - Hot channel Clad temperature

0

200

400

600

800

1000

1200

0 500 1000 1500 2000 2500 3000 3500Time (s)

Tem

pera

ture

(°C)

Run-down provided

Run-down calculated

LOFA Results [6/7] - Power trend in DHR HX (provided run-down curve)LOFA Results [6/7] - Power trend in DHR HX (provided run-down curve)

-2.0E+05

0.0E+00

2.0E+05

4.0E+05

6.0E+05

8.0E+05

1.0E+06

1.2E+06

1.4E+06

1.6E+06

0 500 1000 1500 2000 2500 3000 3500

Time (s)

Pow

er (W

)

1st DHR heat exchanger

2nd DHR heat exchanger

LOFA Results [7/7]LOFA Results [7/7]

• TwoTwo transient-cases analyzed transient-cases analyzed

1.1. provided run-down curveprovided run-down curve

2.2. calculated run-down curvecalculated run-down curve

• DHR Valves open in DHR Valves open in 170 s170 s from LOFA in 1 from LOFA in 1stst case, and in case, and in 600 s600 s in 2in 2ndnd case case

• Second transient Second transient less severeless severe than first one than first one lower pressure peak lower pressure peak lower cladding temperature peak lower cladding temperature peak

• Natural CirculationNatural Circulation occurs at: occurs at: 370 s first case370 s first case 870 s in second case (from LOFA)870 s in second case (from LOFA)

• No differences can be found after 1700 s from LOFA for both No differences can be found after 1700 s from LOFA for both transientstransients

• Equilibrium conditions reached after 2600 s from LOFAEquilibrium conditions reached after 2600 s from LOFA

ConclusionsConclusions

• RELAP5-3DRELAP5-3D©© confirmed to be a valid and a reliable confirmed to be a valid and a reliable tool for the development of GCFR technologytool for the development of GCFR technology

• Model developed can be applied and tested for other Model developed can be applied and tested for other transientstransients

• Further data needed for extensive qualificationFurther data needed for extensive qualification

• Future works:Future works: Improvements of MHX model using cylindrical Improvements of MHX model using cylindrical

geometry MULTIDgeometry MULTID Add 0D and 3D NK feedbackAdd 0D and 3D NK feedback