Fissuration des culasses des moteurs diesel de

secours du parc 900 MWe

Cylinder heads cracking of 900 MWe reactors back-

up diesel generators

Salome-Meca 2018 users day – March 20th – EDF Lab Paris-Saclay

Robin Degeilh, Dominique Geoffroy, Samuel Géniaut, David

Haboussa (R&D/ERMES), François Curtit (R&D/MMC)

Client : Fréderic Gaudeaux (DPN/UNIE/GMAP)

| 2Cylinder heads cracking of 900 MWe reactors back-up diesel generators

INTRODUCTIONCONTEXT

30 x start / shut down per year

| 3Cylinder heads cracking of 900 MWe reactors back-up diesel generators

INTRODUCTIONCONTEXT

| 4Cylinder heads cracking of 900 MWe reactors back-up diesel generators

INTRODUCTIONCONTEXT

Valves bridge cracking

Crack

Water cooling

Combustion chamber

| 5Cylinder heads cracking of 900 MWe reactors back-up diesel generators

INTRODUCTIONCONTEXT

Can bridge cracks propagate up to motor failure ?

UNIE: Need to define (and justify to ASN) the maintenance program

| 6Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Thermal simulation of a start / shut

down motor cycle

Determination of crack growth rate

SUMMARY

Conclusion

Mechanical simulation of a start /

shut down motor cycle

Realisation of the CAD model and

mesh

1

6

5

4

3

2

Ma

teria

l Th

erm

o-m

ec

ha

nic

al

pro

pe

rties

| 7Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Thermal simulation of a start / shut

down motor cycle

Determination of crack growth rate

SUMMARY

Conclusion

Mechanical simulation of a start /

shut down motor cycle

Realisation of the CAD model and

mesh

1

6

5

4

3

2

Ma

teria

l Th

erm

o-m

ec

ha

nic

al

pro

pe

rties

| 8Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Tests

at

20,

220

and 4

20°C

Monotonous tensile test

Cyclic compression/tensil test

Fatigue propagation test

IDENTIFICATION OF THERMO-MECHANICAL PROPERTIESEXPERIMENTAL CHARACTERIZATION

Cast iron GJL300 from

rejected cylinder heads

Elastic-plastic behaviour

| 9Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Tests

at

20,

220

and 4

20°C

Monotonous tensile test

Cyclic compression/tensil test

Fatigue propagation test

IDENTIFICATION OF THERMO-MECHANICAL PROPERTIESEXPERIMENTAL CHARACTERIZATION

Tension/compression

dissymmetry

Growing symmetrical strain controlled test

Applie

d s

train

0

| 10Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Tests

at

20,

220

and 4

20°C

Monotonous tensile test

Cyclic compression/tensil test

Fatigue propagation test

IDENTIFICATION OF THERMO-MECHANICAL PROPERTIESEXPERIMENTAL CHARACTERIZATION

Température Cmoyen mmoyen

20°C 1,77E-12 6,65

220°C 3,98E-12 6,55

420°C 1,83E-11 6,50

| 11Cylinder heads cracking of 900 MWe reactors back-up diesel generators

IDENTIFICATION OF THERMO-MECHANICAL PROPERTIESCONSTITUTIVE MODEL DEVELOPMENT

code_aster

Identification at 20, 220 and

420°C

Implementation MFront

Development

non-linear kinematic

hardening function of

sign of trace(σ)

| 12Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Thermal simulation of a start / shut

down motor cycle

Determination of crack growth rate

SUMMARY

Conclusion

Mechanical simulation of a start /

shut down motor cycle

Realisation of the CAD model and

mesh

1

6

5

4

3

2

Ma

teria

l Th

erm

o-m

ec

ha

nic

al

pro

pe

rties

| 13Cylinder heads cracking of 900 MWe reactors back-up diesel generators

NUMERICAL MODEL3D CAD

| 14Cylinder heads cracking of 900 MWe reactors back-up diesel generators

NUMERICAL MODEL3D SANE MESH

640 000 nodes

Element size ~2mm

| 15Cylinder heads cracking of 900 MWe reactors back-up diesel generators

NUMERICAL MODEL3D CRACKED MESHES

One crack per bridge 3 meshes

28mm

20mm

Maximal measured length according to UNIE

Zcracks

| 16Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Thermal simulation of a start / shut

down motor cycle

Determination of crack growth rate

SUMMARY

Conclusion

Mechanical simulation of a start /

shut down motor cycle

Realisation of the CAD model and

mesh

1

6

5

4

3

2

Ma

teria

l Th

erm

o-m

ec

ha

nic

al

pro

pe

rties

| 17Cylinder heads cracking of 900 MWe reactors back-up diesel generators

T=20°C

Start

Temperature stabilisation

Shut down

THERMAL SIMULATION OF A MOTOR CYCLEBOUNDARY CONDITIONS - START

Exchange

condition

Exchange condition

Exchange

condition

Exchange condition = h(r)

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250 300

Te

mpé

ratu

re (

°C)

Temps (s)

PAA

PAE1

PAE2

PEE

r

| 18Cylinder heads cracking of 900 MWe reactors back-up diesel generators

T=20°C

Start

Temperature stabilisation

Shut down

THERMAL SIMULATION OF A MOTOR CYCLEBOUNDARY CONDITIONS - STABILISATION

Exchange

condition

Exchange condition

Exchange

condition

Exchange condition = h(r)

r

0

50

100

150

200

250

300

350

400

450

500

0 20 40 60 80 100 120 140

Te

mp

era

ture

(°C

)

Radius (mm)

Mesure

Calcul

| 19Cylinder heads cracking of 900 MWe reactors back-up diesel generators

0

50

100

150

200

250

300

350

400

300 2 300 4 300 6 300 8 300 10 300 12 300 14 300 16 300

Te

mpe

ratu

re (

°C)

Time (s)

PAA

PAE1

PAE2

PEE

T=20°C

Start

Temperature stabilisation

Shut down

THERMAL SIMULATION OF A MOTOR CYCLEBOUNDARY CONDITIONS – SHUT DOWN

Exchange condition(water flow /50)

| 20Cylinder heads cracking of 900 MWe reactors back-up diesel generators

THERMAL SIMULATION OF A MOTOR CYCLERESULT

| 21Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Thermal simulation of a start / shut

down motor cycle

Determination of crack growth rate

SUMMARY

Conclusion

Mechanical simulation of a start /

shut down motor cycle

Realisation of the CAD model and

mesh

1

6

5

4

3

2

Ma

teria

l Th

erm

o-m

ec

ha

nic

al

pro

pe

rties

| 22Cylinder heads cracking of 900 MWe reactors back-up diesel generators

MECHANICAL SIMULATION OF A MOTOR CYCLEBOUNDARY CONDITIONS

normal displacement=0

r

| 23Cylinder heads cracking of 900 MWe reactors back-up diesel generators

MECHANICAL SIMULATION OF A MOTOR CYCLERESULT ON SANE MESH

End of start End of shut down

| 24Cylinder heads cracking of 900 MWe reactors back-up diesel generators

MECHANICAL SIMULATION OF A MOTOR CYCLERESULT ON SANE MESH

End of start

End of shut down

End of start End of shut down

Linear mesh

Quadraticmesh

Depth (mm)

| 25Cylinder heads cracking of 900 MWe reactors back-up diesel generators

MECHANICAL SIMULATION OF A MOTOR CYCLERESULT ON CRACKED MESH

| 26Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Thermal simulation of a start / shut

down motor cycle

Determination of crack growth rate

SUMMARY

Conclusion

Mechanical simulation of a start /

shut down motor cycle

Realisation of the CAD model and

mesh

1

6

5

4

3

2

Ma

teria

l Th

erm

o-m

ec

ha

nic

al

pro

pe

rties

| 27Cylinder heads cracking of 900 MWe reactors back-up diesel generators

DETERMINATION OF CRACK GROWTH RATERESULTS IN ΔK

Post-treatment with POST_K1_K2_K3 (elastic)

Cracking rateParis law

Curvilinear abscise (mm)

Bridge C

Bridge A

Bridge D

| 28Cylinder heads cracking of 900 MWe reactors back-up diesel generators

DETERMINATION OF CRACK GROWTH RATERESULTS IN CRACK GROWTH

Bridge A Bridge C Bridge D

1500 start / shut down

Margin=7,10mm Margin=7,01mmMargin=7,75mm

| 29Cylinder heads cracking of 900 MWe reactors back-up diesel generators

Thermal simulation of a start / shut

down motor cycle

Determination of crack growth rate

SUMMARY

Conclusion

Mechanical simulation of a start /

shut down motor cycle

Realisation of the CAD model and

mesh

1

6

5

4

3

2

Ma

teria

l Th

erm

o-m

ec

ha

nic

al

pro

pe

rties

| 30Cylinder heads cracking of 900 MWe reactors back-up diesel generators

CONCLUSION

Note EDF R&D 6125-1716-2017-00547-FR « Projet MODERN - Justification de la tenue des culasses des moteurs diesels des tranches 900 MWe (LP 3.6) »

Can bridge cracks propagate up to motor failure ?

Bridge cracks cannot propagate up to motor break down over 1500 start / shut down

• Experimental mechanical characterisation

• New cyclic inelastic behaviour model in MFront

• 3D complex shape CAD from plans

• Thermo-mechanical study in code_aster

Questions ?