CATHARE CODE FOR GAS-COOLED REACTORS · CATHARE CODE FOR GAS-COOLED REACTORS ... – Reactor safety analysis (Western PWR and ... allowed to give recommendations on friction and heat

First Technical Meeting of INPRO Collaborative Project on

“Performance Assessment of Passive Gaseous Provisions – PGAP”

16-17 June, 2008, Cadarache, France

CATHARE CODE FOR GAS-COOLED REACTORS

F. Bentivoglio, G. Geffraye, T. Germain, A. Messié, N. Tauveron

CEA, DEN/DER




• 4 partners : EDF, AREVA-NP, IRSN, CEA – Developed by CEA since 1979

• Main applications of the code : – Reactor safety analysis (Western PWR and WWER, BWR, RBMK, Fusion

reactor, advanced safety systems, GCR…)

– Plant operation procedures & accident management

– Basis for reactor simulators (training and safety analysis)

– R&D

• CATHARE release: – Release of improved versions every two/three years

– additional modules, improved set of physical models…

– User documentation

V2.5_1 released end of 2005

V2.5_2 to be released end of 2008

• International : – CATHARE is delivered in 15 countries

CATHARE project




2-fluid 6-equation model

the physical models describe the behavior from one phase liquid (water) to one-phase gas (vapor or non condensable gas)

3 equations per phase : energy, mass, momentum

6 principal variables : P, Hl, Hg, , vl, vg

+ Xi (i=1, 4) non condensable mass fraction in gas phase (with related transport equations)

Rmk: In single phase gas flow, the 3 liquid equations are conditioned

so that:

= max =1-10-6, Tl=Tsat, Vl=Vg

Main features




• Space

– Finite volumes (mass, energy) and finite differences (momentum)

discretization

– First order upwind scheme for convective terms (under option: 2nd

order scheme for enthalpy equation)

• Time

– Fully implicit (0 et 1D) discretization

– Implicit wall conduction ( + implicit coupling with hydraulic)

Non linear system solved by the Newton-Raphson

iterative method

Numerical features




• A modular structure : Use a set of objects to represent any kind of hydraulic circuit

• Types of objects : – Main modules

– Sub Modules multi-layer wall, point neutronics (core), fuel pin thermo-mechanics,

exchangers…

– Gadgets connected to one point (scalar or vector)

TEE, source, sink, accumulator, break, valves, pump...

Modeling




OD turbomachinery module (circulator axial and radial

type, turbine, shaft, generator)

Neutron kinetics feedback model specific to the GCR

(Doppler effect, He density effect,...)

Option “single-phase” flow

Physical correlations (gas properties, gas mixture,

specific components correlations (HX)…)

38mm

Steal

th

Air + Hélium

inside the

containment

1 2 . 24

K m W th

Text =

40°C

Break

Axial (1) Axial (2)

Adapted for all the different concepts of Gas-Cooled Reactors (GCR) with specific features integrated as independent options in the standard version of CATHARE

CATHARE for gas cooled reactors




Recuperator

Inter Cooler

Turbo machinery

Electric Heater

Pre Cooler

Validation on experimental data: 3 steps

•Validation on Component Tests (recuperator,

turbomachinery…)

=> HEDYT, HECO… (France)

•Validation on System Tests Facility to take into account all the

dynamic interactions during transient situations, including

regulations

EVO II (Helium turbine plant, Germany),

EVOI (Air turbine plant, Germany)

PBMM (Pebble Bed Micro Model, South Africa)

HEFUS-3 (Eight-loop Helium test facility, Italy) in progress

Code to code benchmarks EVO II

PBMM

•Validation on Separate Effect Tests to get the adequate heat

transfer and pressure drop coefficients for all the flow conditions (in

the core and heat exchangers)

=> ESTHAIR , ESTHEL (France)




Validation of CATHARE for GCR : natural convection flows

1st step: comparison with analytic calculation

T3= 170 °C

P3 = 9.75 bar

1

2

3

T1= 44.47 °C

P1 = 9.5 bar

T2= 50 °C

P2 = 10 bar

Qe = 18.6 Kg/s

Qa = 4.1 Kg/s

Coeur

495 kW518 kW

22.6 kW

T3= 170 °C

P3 = 9.75 bar

1

2

3

T1= 44.47 °C

P1 = 9.5 bar

T2= 50 °C

P2 = 10 bar

Qe = 18.6 Kg/s

Qa = 4.1 Kg/s

Coeur

495 kW518 kW

22.6 kW

T3= 170 °C

P3 = 9.75 bar

1

2

3

T1= 44.47 °C

P1 = 9.5 bar

T2= 50 °C

P2 = 10 bar

Qe = 18.6 Kg/s

Qa = 4.1 Kg/s

Coeur

495 kW518 kW

22.6 kW

T3= 170 °C

P3 = 9.75 bar

1

2

3

T1= 44.47 °C

P1 = 9.5 bar

T2= 50 °C

P2 = 10 bar

Qe = 18.6 Kg/s

Qa = 4.1 Kg/s

Coeur

495 kW518 kW

22.6 kW

2nd step : code / code benchmark :

The ETDR benchmark

3rd step : Comparison with experimental data :

The SALSA facility




Hydraulic SUB-MODULES

Source, Sink, Break without or with sonic flow

Relief, Safety, Control and Check valves and flow limiter with chocked flow

OD pump with predictions of the pump cavitation

Heat Source and Sink

0D accumulator

Point kinetics

Turbo-machines (Gas cooled reactor)

…

Thermal SUB-MODULES Radial Heat Conduction

Multi-layer Wall

Heat exchanger

Fuel Rod

Fuel Thermo-mechanics

Cladding deformation

Cladding Rupture

Cladding Oxidation

…

A Modular Code : able to model SET, IET & all reactor type

Modeling




A Modular Code : able to model Separate Effect Tests, Integral Effect Tests & all reactor type

1D Module (or pipe)

with or without Tees

OD Module (or volume)

3D Module (for the whole pressure vessel)

Pipe flow Annular flow Rod bundle flow

Modeling




Objectives of ESTHAIR program

Steps

•Step 1 : air tests (Reynolds similarity)

•Step 2 : specific helium tests (ESTHEL)

if clad temperature margins are to low (respect to safety criteria)

ESTHAIR program aims at producing estimations of pressure drop and heat exchange coefficients for the various ETDR assembly concepts

The first test section ESTHAIR 1 deals with fuel rod assembly using a wire wrap spacer system to maintain the rods in the triangular arrangement

Main characteristics

Drod:16 mm ; H = 1.65 m

p/d = 1.24

Rod heating power:0 to 2 kW

Operating conditions

300<Re<5 104 , Umax: 50 m/sec

To=218°C (dr/r)*=1 (inlet-outlet)

To=127°C (dr/r)*=1

(outlet boundary layer)

Reynolds similarity (Re scale =1) same relative variations of physical

properties as in the prototype




ESTHAIR outcomes

The first test section (fuel rod assembly using a wire wrap spacer system) has allowed to give recommendations on friction and heat transfer coefficients for design studies

Friction : REHME correlation

Heat transfer : BAXI or Mac ELIGOT correlations

Under progress

Introduction of ESTHAIR correlations in CATHARE

Validation of TRIO-U

New test section representing a portion of a typical ETDR plate assembly

0.0050

0.0100

0.0150

0 5000 10000 15000 20000 25000 30000

Re (dh assembly)

ES

TH

AIR

fri

cti

on f

acto

r

f ESTHAIR unheatedtests

f ESTHAIR heatedtests 1st series

f ESTHAIR heatedtests 2nd series

f Blasius

f Laminar

f REHME

f BAXI

Nominal condition




Validation on EVO – Oberhausen II

It’s unique opportunity to validate CATHARE

on a large-scale helium Brayton cycle.

Validation calculations performed for

four nominal states corresponding to:

• the design specification established in

1972 (Bammert & Deuster, 1974)

• the normal operating conditions of the real

installation between 1974 and 1988

(Bammert et al., 1983), completed with two

partial load conditions

Validation calculations performed for 2

transients : loss of load and load following.

Proposed as benchmark test cases in the

frame of the European project RAPHAEL

Gear Box

Burner

HP

Turbine LP

Turbine

LPC

Recuperator

Precooler

Intercooler

HPC

Oberhausen II, operated by the German utility EnergieVersorgung Oberhausen (EVO), is

a 50 MW(e) direct-cycle helium turbine plant





Turbo-machinery rotation speed

0

100

200

300

400

500

600

700

0 5 10 15 20 25 30 35

Time (s)

Ro

tati

on

sp

eed

(ra

d/s

)

Cathare calculation

Publication

Heater mass flow rate

0

10

20

30

40

50

60

70

80

90

0 5 10 15 20 25 30 35

Time (s)

Ma

ss

flo

w r

ate

(k

g/s

)

CATHARE calculation

Publication

Low Pressure turbine outlet temperature

300

400

500

600

700

800

0 5 10 15 20 25 30 35

Time (s)

Te

mp

era

ture

(°C

)

CATHARE: Recuperator inletCATHARE Turbine OutletPublication : Recuperator inletPublication : Turbine Outlet

Loss of load transient :

High and Low pressure turbines pressures

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

3.0E+06

0 5 10 15 20 25 30 35

Time (s)

Pre

ssu

re (

bar)

CATHARE THP inlet

CATHARE TBP outlet

Publication THP inlet

Publication TBP outlet





Mass Flow Rate in primary loop

35

37

39

41

43

45

47

49

51

53

55

0 200 400 600 800 1000 1200

Time(s)

Mas

s F

low

Rat

e (k

g/s

)

E.V.O Data

CathareCalculation

Load following transient :

HP Turbine Outlet Pressure

6

6.5

7

7.5

8

8.5

9

9.5

10

0 200 400 600 800 1000 1200

Time (s)

Pre

ssu

re (b

ar)

E.V.O Data

CathareCalculation

“Validation of CATHARE code for gas cooled reactors: comparison with E.V.O experimental data on OBERHAUSEN II

favility”, Fabrice Bentivoglio, Nicolas Tauveron. Proceedings of ICAPP ’06 Reno, NV USA, June 4-8, 2006

Paper 6182

“Validation of the CATHARE2 code against Oberhausen II data”, Fabrice Bentivoglio, Nicolas Tauveron, Nuclear

Technology, October 2008.




Validation on EVO – Oberhausen I

Oberhausen I, operated by the German utility EnergieVersorgung Oberhausen (EVO), is

a 13 MW(e) direct-cycle air turbine plant

Validation calculations are performed for 2 nominal states and 4 transients: a loss

of electrical load without turbo-machine trip (13 to 0 MWe), two trip house load (from two

nominal states : 9.9 to 5.7 MWe and 7.4 to 3.1 MWe) and an opening and closure of the

by-pass valve.





Turbo-machine speed

2700

2800

2900

3000

3100

3200

3300

0 5 10 15 20 25Time (s)

Ro

tati

on

Sp

eed

(rd

/min

) E.V.O Data

CATHARE Calculation

Mass flow rate over turbo-machine bypass line

0

50

100

150

200

250

300

0 5 10 15 20 25Time (s)

Mas

s f

low

ra

te (

kg

/s)

E.V.O Data

CATHARE Calculation

Loss of electrical load without turbo-machine trip :





Mass flow rate over turbo-machine bypass line

0

5

10

15

20

25

30

35

40

45

0 10 20 30 40 50 60 70

Time (s)

Mass f

low

rate

(k

g/s

)

CATHARE Calculation

E.V.O Data

“Validation of the CATHARE code against experimental data from Brayton cycle plants”, F. Bentivoglio, G. Geffraye,

Proceedings HTR2006: 3rd International Topical Meeting on High Temperature Reactor Technology, October 1-4, 2006,

Johannesburg, South Africa. Paper C00000228.

“Validation of the CATHARE2 code against experimental data from Brayton cycle plants”, Fabrice Bentivoglio, Nicolas

Tauveron, Geneviève Geffraye, Hervé Gentner. Nuclear Engineering and Design (NED), October 2008.

Electrical Power available on the shaft

0

2

4

6

8

10

12

14

16

0 10 20 30 40 50 60 70

Time (s)

Ele

ctr

ica

l p

ow

er

(MW

)

CATHARE Calculation

E.V.O Data

Opening and closure of the by-pass valve:




Validation on PBMM

The Pebble Bed Micro Model (PBMM) is a full functional model of the Power

Conversion Unit of the Pebble Bed Modular Reactor, new type of high

temperature gas-cooled nuclear power plant currently under development in

South Africa

PBMM aims to demonstrate the ability of system codes to accurately predict

the dynamic behavior of the system.

HPT

ELCPT

LPT

HSIC

PC

LPC

HPC

SBS

ELHX

V34

V33

PTCV

GBP

SIV

SBSIV

SBSOV

RXRX

1

2

3

4

5 6

7

8

9

10

11

12

13 14

16

15

• Based on a Brayton recuperative cycle

• Working fluid: nitrogen

• Use of three separate shafts: High

Pressure Compressor/Turbine, Low Pressure

Compressor/Turbine, Power

Turbine/Generator

• Flow rate, primary circuit ~ 0.4-0.5kg/s

• Maximum cycle temperature: 700 ˚C.

• Maximum cycle pressure: 900 kPa.




Validation on PBMM

• 2 steady states (2 different levels of pressure)

• Several transients

– Load rejection

– Load following (mass injection/extraction)

– Start-up

• Comparison code/code

in particular with FLOWNEX a dynamic systems CFD simulation code developed by South Africa, extensively used for the SA PBMR project

• Comparison to experiment

Significant differences between experiment and calculations for steady states

Overall the two codes agree well.

The Pebble Bed Micro Model is currently subject to an international benchmark for simulation

codes in the CRP5 program, under the auspices of the IAEA.




Load Following transient results

95

100

105

110

115

120

0 50 100 150 200 250 300 350

Time [s]

Pre

ssure

[kP

a]

FNX CAT

0

2

4

6

8

10

12

14

16

18

20

0 50 100 150 200 250 300 350

Time [s]

Po

wer

[kW

]

.

20

25

30

35

40

45

Sp

ee

d [

Rpm

x10

00

]

Power (CAT) Power (FNX) Speed (CAT) Speed (FNX)

LPC suction pressure

P drops from 120kPa to 106kPa

when injection stops

Power turbine power and speed




Benchmarks code/code

TRACE (PSI), RELAP (ENEA,NRI,ANL,CIRTEN,INL,NNC), FLOWNEX (SA, GERMANY), MANTA (AREVA), SPECTRA (NRG), TRAC/AAA (PSI),…

0

20

40

60

80

100

120

140

160

180

200

150 200 250 300 350

Time [s]

ma

ss

flo

w [

kg

/s]

TRACE

CATHARE

GFR 2400MWth, LOCA mass flow through the break

Code / code benchmarks

Loss of load: Core temperatures

400

500

600

700

800

900

1000

0 200 400 600 800 1000

Time (s)

Tem

per

atu

re (

°C)

Core inlet (Manta)

Core inlet (Cathare)

Core outlet (Manta)

Core outlet (Cathare)

VHTR ANTARES, LOCA core inlet and outlet temperature




Analytical approach

W > 0

W < 0

m

Thot

Tcold H 3

0 ..².².²..2

.².

r HgCpS

kWT

3

0

3

1

..².²..2

.

r HgS

kCp

Wm

Natural convection flow in a circuit with

Boussinesq approximation ( ) : T rr 0

Assuming that helium is a perfect gas

and that the total mass of helium in the circuit is constant :

3

3

2

0

3

1

0

.².²..2

.².

HgCpS

kWTT

r33

1

0

3

1

3

2

0

.²..2

.

HgS

kCpT

Wm

r




Analytical approach

m

m

W = 500000 W W = 1000000W W = 2000000 W W = 3000000 W

ΔT analytic 119 °C 190 °C 302 °C 396 °C

ΔT Cathare 114°C 181 °C 292 °C 388°C

analytic 0.81 kg.s-1 1.01 kg.s-1 1.27 kg.s-1 1.46 kg.s-1

Cathare 0.845 kg.s-1 1.06 kg.s-1 1.32 kg.s-1 1.5 kg.s-1

m

m

W = 500000 W W = 1000000W

Calcul

CATHARE

Approche

analytique

Calcul

CATHARE

Approche

analytique

ΔT , T0 = 1000°C 187°C 196°C 300 °C 313°C

ΔT , T0 = 500°C 114°C 119°C 181 °C 190°C

, T0 = 1000°C 0.52 kg.s-1 0.49 kg.s-1 0.64 kg.s-1 0.61 kg.s-1

, T0 = 500°C 0.845 kg.s-1 0.81 kg.s-1 1.06 kg.s-1 1.01 kg.s-1

Comparison between CATHARE and analytical results:

Maximum difference between CATHARE and analytical results :

5% for mass flow rate and 2% for temperature




ETDR benchmark

CORE

Water

(y)

PRIMARY

CIRCUIT

DHR LOOP

×3

SECONDARY

CIRCUIT

(c)

(b) (i)

(h)

(g)

(f)

(e) (a)

(d)

(k)

(j)

(w)

(v)

(u)

(t)

(s)

(x)

He

He

Water

Water

He

International benchmark coordinated by the

European GCFR project

6 Thermal-hydraulics code used: Relap5,

TRAC/AAA, Cathare, SIM-ADS, MANTA and

SPECTRA.

9 organism involved : AREVA (France), CEA

(France), NRG (Netherlands), TUD (Netherlands),

AMEC-NNC (UK), INL (USA), CIRTEN (Italy), JRC

IE EURATOM and PSI (Switzerland).

Transient studied : LOFA with Decay Heat Removal

loops in natural convection.

« A GFR benchmark comparison of transient analysis codebased on the ETDR concept », E.Bubelis, D.Castelliti,

P.Coddington, I.Dor, C.Fouillet, E.De Geus, T.D.Marshall, W.Van.Rooijen, M.Schikorr, R.Stainsby. Proceeding of ICAPP

2007, Nice, France, May 13-18, 2007. Paper 7340.




ETDR benchmark

The results submitted by the participants,

on one hand, showed that all the codes

gave consistent results for all stages of the

benchmark but, on the other hand,

revealed some differences in the behaviour

of some reactor parameters during the

transient.

The differences in the results mainly resulted from:

• Modelling of the vessel wall heat structures and other

additional heat structures representing the piping;

• Different vessel pressure drop and flow resistance in the DHR

helium and water loops; also the use or not of a fuel channel

gagging scheme to obtain a uniform core exit temperature in the

fuel channels;

• Different helium inventory in the primary and DHR loops;

• Different heat transfer correlations used for the main and DHR

heat exchangers, as well as different core (rod bundle) heat

transfer correlations; .

1st Phase, blind calculations :

2nd Phase,

With an harmonization of the

relevant parameters

Results in better agreement




Objectives of SALSA program

Main objectives of SALSA for ETDR

1rst basis for system effect validation of CATHARE calculations

T3= 170 °C

P3 = 9.75 bar

1

2

3

T1= 44.47 °C

P1 = 9.5 bar

T2= 50 °C

P2 = 10 bar

Qe = 18.6 Kg/s

Qa = 4.1 Kg/s

Coeur

495 kW518 kW

22.6 kW

T3= 170 °C

P3 = 9.75 bar

1

2

3

T1= 44.47 °C

P1 = 9.5 bar

T2= 50 °C

P2 = 10 bar

Qe = 18.6 Kg/s

Qa = 4.1 Kg/s

Coeur

495 kW518 kW

22.6 kW

T3= 170 °C

P3 = 9.75 bar

1

2

3

T1= 44.47 °C

P1 = 9.5 bar

T2= 50 °C

P2 = 10 bar

Qe = 18.6 Kg/s

Qa = 4.1 Kg/s

Coeur

495 kW518 kW

22.6 kW

T3= 170 °C

P3 = 9.75 bar

1

2

3

T1= 44.47 °C

P1 = 9.5 bar

T2= 50 °C

P2 = 10 bar

Qe = 18.6 Kg/s

Qa = 4.1 Kg/s

Coeur

495 kW518 kW

22.6 kW

Global approach for the similarity analysis The flow regimes, the heat transfert modes, the characteristic times of the reactor should be respected The geometry of a SALSA component may differ from the reactor one if the previous criteria are respected

Transitoire LOFA - Critère débit

Evolution du débit cœur - comparaison SALSA - REDT

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

tadim

Qa

dim

Qad_salsa

Qad_redt

LOFA, Comparaison SALSA/REDT by CATHARE

Core mass flow rate

Design in progress tests in 2010

Evaluation of the representativity of SALSA Comparison SALSA/reactor behavior seen by CATHARE

Documents

CATHARE CODE FOR GAS-COOLED REACTORS · CATHARE CODE FOR GAS-COOLED REACTORS ... – Reactor safety analysis (Western PWR and ... allowed to give recommendations on friction and heat