IAEA Training Workshop on Assessment of Degradation ... · Understanding on the Mechanisms of...

Understanding on the Mechanisms of Irradiation Embrittlement of RPV Steels

andDevelopment of Embrittlement Correlation

Method

30/9/20141

IAEA Training Workshop onAssessment of Degradation Mechanisms of Primary Components in Water Cooled Nuclear Reactors: Current Issues and Future Challenges

Akiyoshi NomotoCentral Research Institute of Electric Power Industry (CRIEPI)

Embrittlement Mechanism : General Consensus

Formation of Cu-enriched clusters (CEC, CRP) in Cu-containing materials Cu core associated with Ni, Mn and Si 2~3 nm in diameter obstacle to dislocation motion dose rate effect exists

Formation of matrix damage (MD) point defect clusters such as dislocation loops or vacancy

clusters, or point defect – solute atom complexes. main contributor to the embrittlement of low Cu materials

Phosphorus segregation on grain boundary P segregation weakens grain boundaries.

P

MD

CECG.B.

Dislocation

Cu

30/9/2014 2

Outline

Part I Irradiation-induced features that cause embrittlement Effect of solute element Effect of temperature Effect of neutron fluence Effect of neutron flux

Part II Embrittlement correlation methods Development of Japanese embrittlement correlation Known unknows and unknown unknows

330/9/2014

Outline



430/9/2014

5

APT characterization of irradiated RPV steel

EW-P2 R7-00561: 30x29x232 nm3, 6.4M atoms

30nm

232nmCu P Si

Clusters consist of Cu, Ni, Mn, Si and P. Cu atoms are at the center. Ni, Mn and Si atoms are around the Cu core, and P atoms are at

the periphery.

High impurity (Cu) weld metal irradiated to high fluence

30/9/2014

High Cu steel0.12Cu, 4x1019n/cm2, E>1MeV

Medium Cu steel0.07Cu, 6x1019n/cm2, E>1MeV

Low Cu steel0.03Cu, 6x1019n/cm2, E>1MeV

Nature of Cu-enriched clusters

Cu-Ni-Si-Mn cluster

Ni-Si-Mn cluster

High Cu steel0.12Cu, 4x1019n/cm2, E>1MeV

35 x 41 x 491 nm3 :13.7M atoms

33 x 38 x 284 nm3 : 8.1M atoms

41 x 49 x 264 nm3 : 11.2M atoms

30/9/2014 6

Cu P Si

Contribution of SC to embrittlement

0

20

40

60

80

100

0 0.02 0.04 0.06 0.08

Vf1/2

T 4

1J

0

50

100

150

200

0.00 0.05 0.10 0.15

RT N

DT

(o C)

Vf1/2

Surveillance data(N. Soneda et al. CRIEPI Q06019, 2007)

MTR irradiated data(JNES PRE Project, N. Soneda et al. JAI 102128, 2009.)

RT N

DT

(oC

)

RT N

DT

(oC

)

Vf1/2 Vf

1/2

Transition temperature shift is almost proportional to Vf1/2 of

solute atom clusters. This relationship between RTNDT and Vf

1/2 is independent of chemical compositions of the clusters.

Slight difference in the slopes is observed between the surveillance data and MTR data.

30/9/2014 7

TEM Observation : Surveillance Materials

Dislocation loops are observed in the RPV materials irradiated in commercial reactors.

Number densities of the loops are relatively low.

50nm50nmB=[011], 3g (g=21-1) B=[133], 3g (g=-110)

0.12Cu : 4x1019n/cm2 0.07Cu : 6x1019n/cm2

Mean size: 2.6 nmNumber density: 1.8x1022 m-3

Mean size: 2.3 nmNumber density: 1.9x1022 m-3

30/9/2014 8

TEM Observation : MTR irradiated materials

Dislocation loop are observed.• Number density is 1021~1022 m-3, and the diameter is 4~5 nm.

Some of the loops are formed near one side of the line dislocations.

930/9/2014

g g

B9-2 (0.04Cu, 6x1019n/cm2) B9-3 (0.04Cu, 12x1019n/cm2)

Dislocation loop formation near line dislocations Clusters are preferentially formed near one

side of dislocation. Some clusters are the rings that lie on the

same plane, suggesting dislocation loops. Some of the other clusters may be small

dislocation loops with solute atom segregation.

●Cu, ●Si, ●P

B9-3: R7_02571, 35.7x41.6x235nm, 8.05M

B9-3: R7_02618, 42.9x49.4x265nm, 12.0M

gB9-3

Presented at ASTM Symposium in 2008.30/9/2014 10

TEM Observation

1130/9/2014

0.0E+00

2.5E+21

5.0E+21

7.5E+21

1.0E+22

0.0E+00 5.0E+19 1.0E+20 1.5E+20

Num

ber d

ensit

y (m

-3)

Fluence (n/cm2, E>1MeV)

0

2

4

6

8

0.0E+00 5.0E+19 1.0E+20 1.5E+20

Mea

n di

amet

er (n

m)


B1

S1

B9

P1B

Both number density and mean diameter increases with increasing fluence.

Number density can be larger because of resolution limit of our TEM measurement.

Num

ber d

ensi

ty (m

-3)

Mea

n di

amet

er (n

m)

Fluence (n/cm2, E>1MeV) Fluence (n/cm2, E>1MeV)

Estimates of T due to dislocation loops

1230/9/2014

0

50

100

150

200

0 50 100 150 200

Estim

ated

T

due

to d

isl lo

op (

o C)

RTNDT (oC)

B1

S1

B9

P1B

dNbM

65.0NDTRT

: 0.4M : 2

Orowan model:

Embrittlement mechanism: revised

Copper-enriched cluster Matrix damage Phosphorus segregation on

grain boundary

P

MD

CRP G.B

Disl.

Cu

Solute atom cluster Dislocation loop

MD

SC G.B.

Disl.

Solute atom

30/9/2014 13

Outline



1430/9/2014

Effect of solute element

Copper is the most harmful element.

Synergetic effect of copper and nickel has been well recognized since the work by Hawthorne (1982).

Phosphorus?

Manganese?

30/9/2014 15

Effect of Ni : IVAR Materials

1630/9/2014

ID TypeComposition / wt%

Cu Ni Mn Cr Mo P C Si S Fe

CM15A533BPlate

0.22 0.02 1.59 0.02 0.58 0.002 0.14 0.15 0.003 Bal.

CM16A533BPlate

0.22 0.82 1.58 0.00 0.51 0.004 0.16 0.25 0.000 Bal.

CM17A533BPlate

0.22 1.59 1.54 0.00 0.50 0.004 0.16 0.25 0.000 Bal.

ID Flux(x1012n/cm2/s, E>1MeV)

Fluence(x1019n/cm2, E>1MeV)

Temperature(℃)

T16 0.3 1.6 290

Chemical composition

Irradiation Condition

1730/9/2014

Ni Effect of Ni on 0.22Cu-xNi-1.6Mn alloys

20nm

Dislocation

1.59wt%Ni(CM17)(78x80x220nm, 31M atoms)

0.82wt%Ni(CM16)(89x88x230nm, 41M atoms)0.02wt%Ni(CM15)

(85x85x260nm, 41M atoms)

φt=1.6x1019 n/cm2, φ=3x1011 n/cm2/s, T=290oC

●Cu●Si●P

1830/9/2014

0.E+00

1.E+23

2.E+23

3.E+23

4.E+23

5.E+23

0.0 0.5 1.0 1.5 2.0Ni content (wt%)

Clu

ster

Num

ber D

ensi

ty (m

-3)

3.0

3.2

3.4

3.6

3.8

0.0 0.5 1.0 1.5 2.0Ni content (wt%)

Clu

ster

Dia

met

er　

(nm

)

0.0E+00

2.0E-03

4.0E-03

6.0E-03

8.0E-03

1.0E-02

1.2E-02

0.0 0.5 1.0 1.5 2.0Ni content (wt%)

Clu

ster

Vol

ume

Frac

tion

0%

20%

40%

60%

80%

100%

0.02 0.82 1.59Ni content (wt%)

Clu

ster

Com

posi

tion

(at.%

)

CPSiCuNiCrMnFe

Effect of Ni on 0.22Cu-xNi-1.6Mn alloysN

umbe

r den

sity

(m-3

)

Gui

nier

diam

eter

(nm

)

Volu

me

frac

tion

Ni content (wt.%) Ni content (wt.%)

Ni content (wt.%) Ni content (wt.%)

Com

posi

tion

(at.%

)

Effect of Ni on Hardening

G.R. Odette, G.E. Lucas, ASTM STP 1046 (1990) 323. H. Shibamoto, et al., ASTM STP 1405

(2001) 722.

30/9/2014 19

Increase in nickel content causes hardening even in very low or no copper materials.

Number density of dislocation loops increases and loop size decreases in nickel containing materials.

Effect of Phosphorus

Effect of P has been widely accepted, but the mechanism has not been identified yet.

Non hardening embrittlement due to P segregation on grain boundaries is a possibility, but it seems that this is not the mechanism of P effect in western-type RPV materials.

There is a data indicating that P plays a role in low Cu materials but not in high Cu materials. P contributes to hardening by forming precipitates. Recent US correlation method

P atoms are found mostly on dislocation lines and solute atom clusters (APT). They agglomerate to such features very quickly.

30/9/2014 20

Effect of P in low and high Cu materials

P effect is evident only in low Cu materials.

Very little data are available in the surveillance database for low Cu & high P materials. It is not easy to separate the

effect of P from that of Cu.

Hawthorne, 1986.30/9/2014 21

Effect of Mn on Hardening

Mn effect may exist in RPV materials.

Fe-Mn model alloy also shows larger embrittlement than pure Fe. (A. Kimura, et al.) Mn clusters are also observed in

Fe-Mn model alloy. (Y. Nagai, et al.) Fe-ion irradiation of Fe-Mn alloy

shows similar results.

Fe-ion irradiationRT, 0.3dpa, 3.8x10-5dpa/s

30/9/2014 22

Nominal Mn vs LEAP Mn

The Mn contents measured by APT is far less than the nominal bulk Mn contents, and there is non trivial scatter.

Carbides detected by LEAP contain a lot of Mn atoms.

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.30 1.40 1.50 1.60

Mn

Con

tent

by

LEA

P (w

t.%)

Bulk Mn Content (wt.%)

Mn1:1 line

xy

z

Carbide includeing Mn

Direction of composition profile

0

4

8

0 10 20 30 40 50Distance (nm)

Mn Cr NiCu Si P

0

50

100

Fe C

Com

posi

tion

(at.%

)

30/9/2014 23

Outline



2430/9/2014

Effect of temperature

Low temperature irradiation causes larger shifts in both high and low Cu materials.

Empirical linear correlation has been proposed by Jones and Williams for low Cu materials.

A533BShift at Charpy 41JFluence : 1.7x1019n/cm2, E>1MeV

Weld:0.25wt.%Cu

Weld: 0.15wt.%Cu

Base metal: 0.04wt.%Cu

Irradiation Temp. (oC)

D

BTT

(oC

)

J. Ahlf, F.J. Schmitt, IAEA Specialists’ Meeting on “Irradiation Embrittlement and Surveillance of Reactor Pressure Vessels,” IAEA, Vienna, 19-21, Oct. 1981.

30/9/2014 25

Effect of temperature : IVAR materials

2630/9/2014

ID Flux(x1012n/cm2/s, E>1MeV)

Fluence(x1019n/cm2, E>1MeV)

Temperature(℃)

T18 0.36 1.7 270

T16 0.3 1.6 290

T20 0.34 1.6 310

Chemical composition

Irradiation Condition

ID TypeComposition / wt%

Cu Ni Mn Cr Mo P C Si S Fe

LIA533BPlate

0.20 0.74 1.37 - 0.55 0.005 0.16 0.24 0.015 Bal.

LHA533BPlate

0.11 0.74 1.39 - 0.55 0.005 0.16 0.24 0.015 Bal.

Atom Maps : LI (high Cu) materials

2730/9/2014

LI-T1870x70x270nm, 26M atoms

270oC



290oC 310oC

20nm

●Cu●Si●P

Atom Maps : LH (low Cu) materials

2830/9/2014

LH-T1891x91x210nm, 39M atoms



20nm

●Cu●Si●P

270oC 290oC 310oC

0.E+00

2.E-03

4.E-03

6.E-03

8.E-03

1.E-02

260 270 280 290 300 310 320Irradiation　Temperature (℃)

Clu

ster

Vol

ume

Frac

tion LI

LH

Temperature Effect

2930/9/2014

0.E+00

2.E-02

4.E-02

6.E-02

8.E-02

1.E-01


Squa

re ro

ot o

f clu

ster

Vol

ume

Frac

tion

LILH

0.E+00

1.E+23

2.E+23

3.E+23

4.E+23

5.E+23

6.E+23

7.E+23

8.E+23


Clu

ster

Num

ber D

ensi

ty (m

-3)

LILH

2.5

3.0

3.5

4.0


Clu

ster

Dia

met

er　

(nm

) LILH

Num

ber d

ensi

ty (m

-3)

Gui

nier

diam

eter

(nm

)

Volu

me

frac

tion

Squa

re ro

ot o

f Vf

Outline



3030/9/2014

Effect of fluence

The amount of embrittlement is predicted as a power function of fluece with the exponent of 0.15~0.35 for the fluences up to 1x1020 n/cm2, E>1MeV. RG1.99 : 0.28-0.10logf JEAC4201 : 0.29-0.04logf (base metal), 0.25-0.10logf (weld) FIS : 0.35 VVER : 0.29-0.04logf (VVER-440), 0.33 (VVER-1100)

Recent mechanism-guided correlation equations predict that different fluencefunctions for CRP and MD. TMD = A (f)0.5

TCRP = B (1+tanh((log f - C)/D Late Blooming Phase

High Ni and high fluence log f

T

CRP

MD

30/9/2014 31

Fluence effect on the volume fraction of SC

0.0000

0.0025

0.0050

0.0075

0.0100

0.0125

0.0150

0 5 10 15

Volu

me

fract

ion

Fluence (x1019 n/cm2, E>1MeV)

0.0000

0.0025

0.0050

0.0075

0.0100

0.0125

0.0150

0 5 10 15Vo

lum

e fra

ctio

nFluence (x1019 n/cm2, E>1MeV)

B1 (0.21/0.63)

B4 (0.17/0.62)

B5 (0.10/0.59)

B9 (0.04/0.62)

B6 (B5+0.92Ni)

B7 (B5+0.017P)

B8 (B5+0.32Si)

S1 (0.09/0.62)

S1s (0.09/0.62)

S2s

P1B (0.06/0.58)

P2B (0.25/0.59)

P3B (P1B+0.018P)

P4B (P1B+1.78Ni)

W1 (0.20/0.88)

W2 (0.13/0.86)

W3 (0.10/0.88)

W4 (0.02/0.84)

N. Soneda et at., J. of ASTM International, Vol. 6, No. 7, Paper ID JAI102128

JNES PRE Project

30/9/2014 32

Volume fractions of solute atom clusters keep increasing with fluence. This is primarily due to the growth of clusters. Number density does not increase very much with fluence.

Composition change in high-Cu material

3330/9/2014

0

50

100

150

200

250

0 1000 2000 3000 4000 5000 6000

Num

ber o

f Cu atom

s in a cluster

Cluster size

G1

G3

0

20

40

60

80

100

120

140

160

0 1000 2000 3000 4000 5000 6000

Num

ber o

f Si atoms in a cluster

Cluster size

G1

G3

0

20

40

60

80

100

120

140

160

0 1000 2000 3000 4000 5000 6000

Num

ber o

f Ni atoms in a cluster

Cluster size

G1

G3

0

50

100

150

200

250

300

350

0 1000 2000 3000 4000 5000 6000

Num

ber o

f Mn atom

s in a cluster

Cluster size

G1

G3

Cu Si

Ni Mn

φt=1.6(G3), 13(G1) x1019 n/cm2, φ=1x1014 n/cm2/s, T=290oC

Outline



3430/9/2014

Dose Rate Effect in Low Cu Material

3530/9/2014

60

50

40

30

20

10

0

硬化量（MPa）

5 6 7 8 9

10112 3 4 5 6 7 8 9

1012

中性子照射速度（n/cm 2 -s）

　中性子照射量低(~1018n/cm2)

高(~1019n/cm2)

高照射量

低照射量

Incr

ease

in y

ield

stre

ss (

MP

a)Dose rate (n/cm2-s)

Tran

sitio

n te

mpe

ratu

re s

hift

(oC

)

Fluence (x1019n/cm2)

Comparison of French surveillance data and test reactor irradiation data

Comparison of test reactor data irradiated at different fluxes

No clear dose rate effect is observed in low Cu materials.

P. Petrequin, ASMES:1996. Report Number 6 EUR 16455 EN 1996.

CRIEPI/UCSB Joint Program

FluenceLowHigh

Low flux irradiation data in Japan

Very low flux irradiation causes larger shifts.

0

10

20

30

40

50

60

70

80

0.0E+00 5.0E+17 1.0E+18 1.5E+18 2.0E+18 2.5E+18 3.0E+18

Fluence (n/cm2)

Del

ta T

r30

(o C)

Surveillance (A)Surveillance (W)

MTR

SPT1

SPT2

SP1

~109 n/cm2-s~1010 n/cm2-s~1012 n/cm2-s

Cu: 0.24 wt.%

Neutron fluence (n/cm2, E>1MeV)

R

T ND

T(o

C)

30/9/2014 36

0

10

20

30

40

50

60

70

80

0.0E+00 5.0E+17 1.0E+18 1.5E+18 2.0E+18 2.5E+18 3.0E+18

Fluence (n/cm2)

Del

ta T

r30

(o C)

Surveillance (A)Surveillance (W)MTR

SPT1

SPT2

SP1

~109 n/cm2-s~1010 n/cm2-s~1012 n/cm2-s

Surveillance materials study (2)

0

10

20

30

40

50

60

70

80

0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 5.6 6.0

Cluster diameter (nm)

Counts

Cou

nts

Guinier diamter (nm)

SP1Cu 0.24 wt.%t 9x1017 n/cm2

Nd 4.32 x 1023 m-3

Vf 4.39 x 10-3

dG 2.58 nm

Low flux Irradiation (BWR)

0

5

10

15

20

25

30

0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0 4.4 4.8 5.2 5.6 6.0

Cluster diameter (nm)

Cou

nts

Guinier diameter (nm)

Cou

nt

SPT1Cu 0.24 wt.%t 1.3x1019 n/cm2

Nd 2.94 x 1023 m-3

Vf 1.25 x 10-3

dG 1.96 nm

High flux Irradiation (MTR)

R

T ND

T(o

C)

Neutron fluence (oC)

Very low flux irradiation causes larger shifts.

Lower flux irradiation makes Cu-enriched clusters much larger.

Cu: 0.24 wt.%

30/9/2014 37

Outline



3830/9/2014

3930/9/2014

Understanding on the Mechanisms of Irradiation Embrittlement of RPV Steels

andDevelopment of Embrittlement Correlation

Method

30/9/201440

IAEA Training Workshop onAssessment of Degradation Mechanisms of Primary Components in Water Cooled Nuclear Reactors: Current Issues and Future Challenges

Akiyoshi NomotoCentral Research Institute of Electric Power Industry (CRIEPI)

Outline



4130/9/2014

Embrittlement correlations

4230/9/2014

FFCFT J 41US NRC RG1.99r1 (1977)

1980 1990 2000

FIS/FIM (1987)

KTA 3203 (6/01) (2001)

Williams et al. (1988)

EWO (1996)

E900-02 (2002)

Statistics based

Mechanism based

WWER-1000 (2002)

CRPMDJ TTT 41

WR-C(5)Rev.1 (2010)

2010JEAC4201-2013 (2013)

KTA 3203 (3/84) (1984)

WWER-440 (1993)

US NRC RG1.99r2 (1988)JEAC4201-1991 (1991)

Revised EWO (2000)

Fisher et al. (1983, 1985, 1987)Odette, Lucas (1983, 1985)

Williams et al. (2001,2002)

Williams et al. (2010)EDF (2010)

EONY (2007)JEAC4201-2007 (2007)

Debarberis et al. (2005, 2006)

Margolin et al. (2012)Ahlstrand et al. (2012)

Statistics based correlations

4330/9/2014

5.041 08.01000008.0500040

95 fCuPT J

US NRC RG1.99r1 (1977)

US NRC RG1.99r2 (1988)

fJ fNiCuCFT log1.028.0

41 ),(95

FIS (1987)

JEAC4201-1991 (1991)

35.0219108.0238008.01537248 CuNiCuPTT

fJ fCuNiCuPT log04.029.05.0

41 77215121016

fJ fCuNiNiSiT log1.025.05.0

41 301612426

FFCFT J 41

Mechanism based correlation（USA）

4430/9/2014

CRPSMD41 JT

f

c

fPT

ASMD log0597.04449.04

7.571460

10906.1exp95

plates ,10x24.1forgings ,10x98.8

welds,10x10.1

7

8

7

A fGCuFNiBCRP 358.156.2195

plates ,172forgings ,135

welds,209B

wt%0.300 Cu 0.367,

%wt072.0Cu,)072.0(Cu%wt072.0Cu,0

678.0CuF

600.0290.181048.5log

tanh21

21 12

ftffG

EWO (1996)CRPMDJ TTT 41

Mechanism of embrittlement（EWO）

4530/9/2014

0

20

40

60

80

100

120

0 2E+19 4E+19 6E+19 8E+19 1E+20

∆R

TND

T (°

C)

Fluence (n/cm², E>1MeV)

TotalMDCEC/CRP

∆R

T ND

T(°

C)


燐

SMD

CRP 粒界

転位

銅

CRPSMD

: Copper Rich Precipitate: Stable Matrix Damage

（2~3 nanometers）

Cupper enriched clusters and matrix damage cause embrittlement

CRP formation is a function of Copper content, Nickel content and irradiation time and will be saturated.

Effect of temperature and P on MD

Mechanism based correlation（USA）

4630/9/2014

EONY (2007)termCRPtermMFTTS

ei tMnPTAtermMF 47.213.61001718.01

for welds10417.1platesfor 10561.1

forgingsfor 10.1401

7

7

7

A

1010

10

1039.4 1039.41039.4

fort

fortte

eee tNiCugPCufNiBtermC ,,,77.031 RP 191.1

plates SRMfor 128.2for welds 155.0

vesselsmfg. CEin platesfor 35.21 vesselsmfg. CE-nonin platesfor 02.51

forgingsfor 02.31

B

.% 072.0for ,min

.% 072.0for 0wtCuCuMaxCu

wtCuCu

ee

materialsother allfor .3010

welds80 Linde 0.5) (Ni lfor typica 243.0eCuMax

668.0008.0359.1072.0, PCuPCuf ee

629.0

120.18448.0139.1logtanh21

21,, 10 NiCuttNiCug ee

ee

Based on EWOEffective fluence teEffect of Mn

Russia／VVER

4730/9/2014

WWER-1000 (2002)

Debarberis et al. (2005, 2006)

3107.0800 Rk FCuPT

WWER-440 (1993)

3120 Rk FT

dcebaDBTT startn

shiftsat tanh5.05.01

Matrix damage CEC P segregation

France

4830/9/2014

FIS/FIM (1987)

EDF (2010)

35.0219108.0238008.015373.17 CuNiCuPTT

35.0219108.0238008.01537248 CuNiCuPTT

59.028.508.06.6008.07.351 CuNiCuPATT

FIMFIS

Low copper content in French RPV steels

USA

4930/9/2014

BM

CuT

0

052.031.0,MINMAX30

WR-C(5)Rev.1 (2010)

105.058.078.122.4

17

012.01.0

63.0433.0

550

0,3.613,0.13810151.1lnlnMINMAX675.0989.0073.1

PNiT

MMM

M

F

P

W

173.042.035.1105.041.4

5503.010

36.163.055.0

012.01.0

550

10335.9167.1315.1

2.1

MnNiPT

BBB

B

F

P

W

WR-C(5) Rev-1

Statistics based correlation

Not only US surveillance data but also non-US data and MTR data are used for the development ~2400 data

The formula is similar to EONY as a result

Developed by Dr. Mark Kirk (NRC)

30/9/2014 50

Outline



5130/9/2014

Previous Japanese correlation

5230/9/2014

JEAC4201-1991


41 77215121016


41 301612426

ΔT41J, ΔTTCu, Ni, P, Sif,

：DBTT shift（℃）：Content of Cu, Ni, P and Si （wt.%）：Neutron fluence（x1019 n/cm2, E>1MeV）

Statistics based correlations

Prediction by JEAC4201-1991

5330/9/2014

TBD

D s

hift

Neutron fluence (n/cm2, E>1MeV)

6x1019n/cm2

(40years)1x1020n/cm2

(60years)

Hi Cu steelsHigh Cu steels irradiated at low flux

Low Cu steels

Low Cu steels irradiated up to high fluences

JEAC4201-1991Surveillance data


41 77215121016


41 301612426

Development new Japanese correlation

Larger embrittlement in high Cu steels than expected at lower flux conditions.

Trend of embrittlement of low Cu steels irradiated up to high fluences is different from predicted.

New results/knowledge of mechanism of irradiation embrittlement

Development of new correlation based on understanding of mechanism

30/9/2014 54

Embrittlement mechanism

MD

SC G.B.

Disl.

Solute atom

55

Solute atom cluster Dislocation loop

30/9/2014





●Cu, ●Si, ●P

B9-3: R7_02571, 35.7x41.6x235nm, 8.05M

B9-3: R7_02618, 42.9x49.4x265nm, 12.0M

gB9-3


Modeling of microstructural change

5730/9/2014Cu Ni, Mn, Si

High Cu steel Low Cu steel


58

Irradiation defect (dislocation loop)

30/9/2014Cu Ni, Mn, Si


59

Irradiation induced clustersIrradiation enhanced clusters

Matrix damage Matrix damage

Irradiation induced clusters

30/9/2014

Contribution of clusters to embrittlement

監視試験データ(N. Soneda et al. CRIEPI Q06019, 2007)

試験炉照射データ(JNES PRE Project, N. Soneda et al. JAI 102128, 2009.)

0

20

40

60

80

100

0 0.02 0.04 0.06 0.08

Vf1/2

T41

J

0

50

100

150

200

0.00 0.05 0.10 0.15

RT N

DT

(o C)

Vf1/2

RT N

DT

(oC

)

RT N

DT

(oC

)Vf

1/2 Vf1/2

DBTT shift is proportional to sqrt of volume fraction of solute atom clusters Independent of chemical composition

6030/9/2014

Embrittlement due to microstructure

Microstructural change

Japanese correlation (JEAC4201-2007/-2013)

6130/9/2014

2089214 1 NiCu

availCuMDCu

matCu

SC CDCCDCt

C

t

CCFt

C SCNiT

MD

276

25

SCSC

enhSc

SC

matCu Cv

tC

vt

C

21

thermalCu

irradCu

thermalCuCu DDDD

MDMD CT 18

22MDSC TTT

,17 fSC VT SCCuNiSCmatCuf CtDCCCfV

1110

20

1416 11, 15

Japanese correlation

Based on revised embrittlement mechanism Solute atom clusters

Effect of neutron flux

Independent of product form (base metal, weld)

Prediction of "trend" of embrittlement

Offset correction

6230/9/2014

照射量

脆化量

照射量

脆化量 T

tOffset

T

tOffset

脆化量

照射量Fluence

T

Fluence

T

Fluence

T

Surveillance data vs prediction

6330/9/2014

-20

0

20

40

60

80

100

120

140

160

180

200

-20 0 20 40 60 80 100 120 140 160 180 200

Cal

cula

ted

ΔR

T ND

T(°

C)

Measured ΔRTNDT (°C)

Base and weld metalsSRM materialsMTR materials1:1 line±22°C

-20

0

20

40

60

80

100

120

140

160

180

200

-20 0 20 40 60 80 100 120 140 160 180 200C

alcu

late

d Δ

RT N

DT

(°C

)

Measured ΔRTNDT (°C)

Base and weld metalsSRM materialsMTR materials1:1 line±18°C

Outline



6430/9/2014

Known unknows

Unstable matrix feature (UMF) Does high flux irradiation cause larger shifts at high fluences? Is UMF a new phase (MD, CEC + UMF) or anything else?

Late Blooming Phase Ni-Mn-Si phase are formed in low Cu and medium Ni materials

irradiated in both power reactors and MTRs. Does LB phase appear at high fluences in high Ni (and maybe

high Cu) materials? Material effect (?)

CE effect, Linde80 effect, … Product form effect Initial strength effect

Decoration of dislocations by dislocation loops What is the effect of decoration?

30/9/2014 65





●Cu, ●Si, ●P

B9-3: R7_02571, 35.7x41.6x235nm, 8.05M

B9-3: R7_02618, 42.9x49.4x265nm, 12.0M

gB9-3


Unkown unknows

Embrittlement only from micro- and macro-scopic(mechanical property) points of view has been discussed.

30/9/2014 67

Thank you very much for your attention.

6830/9/2014

IAEA Training Workshop on Assessment of Degradation ... · Understanding on the Mechanisms of...

Documents

Transcript of IAEA Training Workshop on Assessment of Degradation ... · Understanding on the Mechanisms of...