R E L A P 5-3D©R E L A P 5-3D©

RELAP5-3D Development &Application Status

Presented byGary W. Johnsen

Idaho National Engineering & Environmental LaboratoryIdaho Falls, Idaho 83415

2001 RELAP5 International User’s SeminarSeptember 5-7, 2001

Sun Valley, Idaho

R E L A P 5-3D©

Outline

• Overview of development andapplication activities

• Selected reviews– Pb-Bi Reactor Studies– ATHENA/RELAP5-3D

Validation• Future activities

R E L A P 5-3D©

Development Activities

* Presentation in Seminar

Item ObjectivePVM Executive for Coupling* Control the startup,

advancement andtermination of tow or morecoupled codes

64 Bit Upgrade Allow for 64 bit integersFurther Parallelization Complete conversion to

OpenMP directives in 3D andkinetics routines

Level Position in a Stack Add output to indicate levelposition in a vertical stack ofvolumes

FORTRAN 90 Bit Packing Convert archaic bit packingto FORTRAN 90 standard

R E L A P 5-3D©

Development Activities (cont’d)Item Objective

Critical Flow Anomaly* Resolve discontinuity nearsaturation line

Stack Fill TemperatureAnomaly

Resolve unphysicaltemperatures while filling avertical stack

RGUI Enhancement* Add heat slab datavisualization

PYGMALION* RefurbishCouple RELAP5-3D toFluent*

Application to HTGR

RELAP5-3DK* Assist INER in developing anAppendix K version

* Presentation in Seminar

R E L A P 5-3D©

Applications at INEELProject Objective

International Nuclear SafetyProgram*

Development, assessment,and training for VVER andRBMK applications

Fusion Safety Assessment ofATHENA/RELAP5-3D

Advanced designs Lead-Bismuth, Pebble Beddesign studies

ATR* Safety margin assessments,design studies

RELAP5/RT* Assist DS&S in simulatorupgrades

Municipal Steam SupplySystems

Design and transient studies

* Presentation in Seminar

R E L A P 5-3D©

Pb-Bi Reactor Studies*

• ATHENA calculations were performed toinvestigate the transient response of three plantoptions:– Natural circulation primary, water secondary– Forced circulation primary, water secondary– Natural circulation primary, helium secondary

• Transients were analyzed to evaluate plantoperability and determine margins to safety limits

* Work performed by Cliff Davis

R E L A P 5-3D©

Pb-Bi Reactor Design

Containment Vessel

Collector Cylinder

ReactorVessel

HeatExchanger

Pb-Bi

Chimney

Core

Air InAir Out

Reactor Silo

Downcomer

Riser

R E L A P 5-3D©

Transients to be analyzed• Operability

– Step change in load– Plant startup

• Accidents– Loss of heat sink with scram– Control rod ejection without scram– Large rupture of secondary outlet piping without scram– Heat exchanger tube rupture without scram– Primary coolant pump trip without scram– Loss of feedwater heating without scram

R E L A P 5-3D©

The plant is not sensitive to a 10%step change in load

0 100 200 300 400Time (s)

0.99

1.00

1.01

Nor

mal

ized

pow

er

NC, H2OFC, H2ONC, He

• Step decrease insecondary pressure at10 s

• Secondary inlet flowassumed constant

• Evaluation of marginto scram, not loadfollowing capability

R E L A P 5-3D©

Scram is required to meet cladding thermallimit following control rod ejection

0 50 100 150 200Time (s)

400

600

800

1000

1200

1400

Tem

pera

ture

(°C

)

NC, H2OFC, H2ONC, HeTransient limit

• 0.5$ step at 10 srepresenting ejection ofaverage control rod(unlikely with fertile-free fuel)

• No scram

• Beyond design basis

• Scram must occurwithin 2 s with naturalcirculation

• More margin existswith forced circulation

R E L A P 5-3D©

The pump should be trippedfollowing a loss of heat sink

0 10 20 30 40 50 60Time (hr)

200

300

400

500

600

700

800

Tem

pera

ture

(°C

)

NC, H2OFC, H2ONC, HeTransient limit

• With scram, pump running

• Q0 = 650 MW

• Traditional RVACS

• Pump heat increases load onRVACS

• If pump is tripped, PCT issimilar to NC case

• Transient limits will be morerestrictive than steady-statelimits for FC

• Initial power should bereduced by 3% to meet thermallimit with helium

R E L A P 5-3D©

The plant is not sensitive to a largerupture of the secondary outlet piping

0 50 100 150 200Time (s)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Nor

mal

ized

pow

er

NC, H2OFC, H2ONC, He

• Q0 = 650 MW

• No scram

• All heat exchangers blowdown, with no flowrestrictors

• Power increases quicklywith natural circulation,delayed until cold waterreaches core with forcedcirculation

• Cladding temperaturesremain below thermal limit

R E L A P 5-3D©

Pb-Bi Design Preliminary Conclusions

• The plant demonstrates good operating characteristics• The most limiting design-basis transient so far is the loss

of heat sink• Scram is required for the loss of heat sink and control rod

ejection accidents• The transient responses of all three plant configurations are

acceptable– Reactor coolant pumps should be tripped or run back following a

loss of heat sink– Reactor scram is almost not required for a control rod ejection

accident with forced circulation

R E L A P 5-3D©

ATHENA/RELAP5-3D ValidationFor Fusion Reactor Studies*

Japanese Ingress of Coolant Experiment (ICE)– Scaled experimental facility simulating a water cooled

tokamak reactor– Purpose of facility

• Measure pressure, choked flow and wall heat transfer duringloss-of-coolant accidents (LOCAs) into superheated evacuatedvessels

• Validate capabilities of fluid flow codes used by the fusioncommunity for safety assessment of reactor designs -ATHENA, MELCOR, CATHARE, TRAC, INTRA, CONSEN

*Prepared by Brad Merrill

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Vacuumvessel

Suppression tank

Plasma chamber

Boiler

Divertor

Japanese Ingress of Coolant Event (ICE)Experiment

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ATHENA/RELAP5 3D ICE EXPERIMENT MODELFluid Cell Placement

Boiler

Vacuumvessel

Nitrogensystem

Plasmachamber

Suppressiontank

Boilerr-Θ-z - 3 x 6 x 3 (60°)

Plasma chamber heatr-Θ-z - 4 x 8 x 7 (45°)

Divertor region dividedinto five cells

Vacuum vesselr-Θ-z - 3 x 4 x 5 (90°)

Suppression tankr-Θ-z - 2 x 1 x 8 (360°)

Nitrogen system, injector lines,relief pipes, 1D components

R E L A P 5-3D©

CASE 02 RESULTS

0 20 40 60 80 100

Tim e (sec)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

Pres

sure

(MPa

)

ATHENA/RELAP-PCATHENA/RELAP-VVATHENA/RELAP-SPATHENA/RELAP-STPI-01PI-02PI-10PI-11

Pressure in Plasma Chamber, Vacuum Vessel Suppression Pipe and Suppression Tank

R E L A P 5-3D©

CASE 02 RESULTS (cont)

0 100 200 300 400 500 600

Time (sec)

140

160

180

200

220

240

Tem

pera

ture

(C)

ATHENA/RELAP-PCA-02-000ATHENA/RELAP-PCA-04-000ATHENA/RELAP-PCA-06-000TPW-02TPW-03TPW-04

Temperature of Plasma Chamber Wall θ = 0

0 100 200 300 400 500 600

Time (sec)

80

120

160

200

240

Tem

pera

ture

(C)

ATHENA/RELAP-PCA-02-045ATHENA/RELAP-PCA-04-045ATHENA/RELAP-PCA-06-045TPW-06TPW-07TPW-08

Temperature of Plasma Chamber Wall θ = 45

R E L A P 5-3D©

Post-test Conclusions forATHENA/RELAP5-3D Comparison

ATHENA/RELAP-3D compared well with ICE testdata provided– homogenous flow velocity model (equal vapor and

liquid) was employed => inter-phase drag model needsto be examined

– post-CHF heat transfer correlations were enhanced by afactor of 7 to simulate droplet impingement => heattransfer models need to be added

R E L A P 5-3D©

Future Activities*Task Objective

Multi-Thread with PVM Permit execution of RELAP5-3Din parallel when coupled to othercodes using the PVMmethodology

Improve Air AppearanceLogic in RELAP5-3D

Modify logic to avoid repeat oftime step

Allow Reflood on Left orRight of Heat Slab

Generalize reflood model fordifferent geometries

FORTRAN 90: fixedcommons, volume block

Convert fixed common blocks toFORTRAN 90 modules andconvert the control volume blockto a FORTRAN 90 module

Resolve BPLU ZeroBandwidth Problem

Find and correct root cause foranomalous zero bandwidthfailures

RGUI Development Model Builder/Editor

*Based on projected funding