advanced materials for fusion technologyadvanced materials for fusion technology s.j. zinkle1 and a....

Advanced Materials for FusionTechnology

S.J. Zinkle1 and A. Kohyama2

1Oak Ridge National Laboratory, Oak Ridge, TN USA 2Institute of Advanced Energy, Kyoto University, Kyoto, Japan

19th IEEE/NPSS Symposium on Fusion Energy

January 22-25, 2002

Atlantic City, New Jersey, USA

OUTLINE

• Development of Improved Materials–Advanced steels, including Nanocomposited ferritic steel–Refractory alloys (V, Mo, W alloys)–New welding technology–Ceramic composites

• Brief comments on prospects for improved Cu alloysand nonstructural materials

INTRODUCTION

• Major design criteria for structural alloys include–Resistance to He embrittlement & swelling from (n,α) reactions

–high temperature strength–low temperature radiation embrittlement resistance–Safety and environmental (disposal) issues

• Major design criteria for ceramic composites include–Thermal conductivity degradation–Reduced-cost fabrication and joining techniques–Safety and environmental (disposal) issues

Low uniform elongations occur in many BCC and FCCmetals after low-dose irradiation at low temperature

Uniform elongation of neutron-irradiated V-4Cr-4Ti

-2

0

2

4

6

8

10

12

0 100 200 300 400 500 600 700

Un

ifo

rm E

lon

gat

ion

(%

)

Test Temperature (˚C)

0.5 dpa

0.1 dpa

Test Temperature isIrradiation Temperature

0

2

4

6

8

10

0.0001 0.001 0.01 0.1 1 10

Fabritsiev et al (1996)Heinisch et al (1992)Singh et al. (1995)

Uni

form

Elo

ngat

ion

(%)

Damage Level (dpa)

Unirradiatedelongations

Tirr

=36-90˚C

Uniform elongation of neutron-irradiated GlidCop Al25 and CuCrZr

0

5

10

15

20

25

30

0 50 100 150 200 250 300 350 400

Uni

form

Elo

ngat

ion

(%)

Irradiation and Test Temperature (˚C)

CuCrZr

ODS Cu

GlidCop Al25

0

100

200

300

400

500

600

700

0 0.05 0.1 0.15 0.2 0.25 0.3

Load-Elongation Curves for V-4Cr-4Ti Irradiated in HFBR to 0.5 dpa

Eng

inee

ring

Stre

ss, M

Pa

Normalized Crosshead Displacement, mm/mm

110˚C 270˚C

325˚C

420˚C

Tt e s t

~Tirr

100 nm100 nm

TTtesttest==TTirrirr=270=270 ˚̊CCg=011

g=011

Irradiated Materials Suffer Plastic Instabilitydue to Dislocation Channeling

Radiation-induced Tensile "Embrittlement" does notNecessarily Produce Fracture Toughness Embrittlement

0

5

10

15

20

0

50

100

150

200

0 50 100 150 200 250 300 350 400

Un

ifo

rm e

lon

gat

ion

(%

)

Fra

ctu

re T

ou

gh

nes

s K

JQ (

MP

a-m

1/2)


CuCrZr, 0.3 dpaTähtinen et al 1998

eU,

irradiated

eU, unirr.

KJ Q

, unirr.

KJ Q

, irradiated

Application of Thermal Defect Resistance Modelto Predict Conductivity of Irradiated SiC

0

0.02

0.04

0.06

0.08

0.1

0.001 0.01 0.1 1

Ad

ded

Th

erm

al D

efec

t R

esis

tan

ce

dpa

690-720 °C

240-270 °C

490-510 °C

TRIST-TC1

Estimated Thermal Conductivity : CVD SiC

1/Krd @t=0 (m-K/W)0.014240-270°C0.008490-510°C0.002690-720°C

( m - W / K )

• Maximum irradiated thermal conductivity for SiC is estimated to be ~ 10 W/m-K at 500°C, ~37 W/m-K at 700°C

0

50

100

150

200

250

300

350

0 200 400 600 800 1000 1200

K (

W/m

-K)

Temperature (C)

Saturation Conductivity for Morton CVD SiC

unirradiatedhigh conductivity

Kirr(T) : W/m-K1/Krd sat.(m-K/W)1 3.07240-270°C1 0.09490-510°C3 7.018690-720°C

1 / Krd

model

1K (T)

1K (T)

1K (T)irr unirr rd

= +

K TK T K T K Ku gb d rd

( )( ) ( )

[ ] = + + +

−1

0

1 1 1 1

0 200 400 600 800 1000 1200 1400

SiC/SiC

CuNiBe

316 SS

F/M steel

ODS ferritic st.

V-4Cr-4Ti

Nb-1Zr-.1C

Ta-8W-2Hf

Mo (TZM)

W

Temperature (˚C)

Current Alloy Systems Have Key Limitations• V-4Cr-4Ti Alloy

- Thermal creep limits- low temperature radiation

hardening- possible He embrittlement- requires MHD coating- poor oxidation resistance

• Ferritic/Martensitic Steels- low temperature radiation

hardening- Thermal creep limits- possible He embrittlement

• Refractory Alloys

Operating Temperature Windows

S.J. Zinkle and N.M. Ghoniem (2000)

Key Feasibility Issues for Ferritic Steels• Verify ferromagnetic structures are acceptable for MFE• Expand low temperature operating limit (experiments and physical

modeling, master curve methodology)– Development of alloys with improved resistance to low

temperature (<350˚C) embrittlement• Expand high-temperature and dose limits

– Alloy development, including dispersion strengthened alloys– Effect of He on creep rupture

• Resolve system-specific compatibility issues (T barrier development,etc.)

IEA-integrated worldwide ferritic steel program is examining items2 &3 (items 1&4 are being addressed by JA and EU programs)

Note: reduced-activation grades of Fe-9Cr ferritic/martensitic steels(e.g., F82H) have been developed with superior properties compared tocommercial steels (e.g., HT9)

Void Swelling of Ferritic Steels is Low up to~100 dpa (~10 MW-yr/m2), Although Further

Work is Needed to Examine He Effects

F82H (36 appm He) 10B-doped F82H (330 appm He)

HFIR irradiation at 400˚C to 51 dpa

Potential New Ferritic/Martensitic Alloy• Dispersion-Strengthened Fe-9.5Cr-3Co-1Ni-0.6Mo-0.3Ti-0.07C steel

– High number density of nano-size TiCprecipitates

• Superior elevated-temperature strengthand impact properties compared toconventional 9-12Cr steels

• Advantage over ODS steels: producedby conventional steel processingtechniques

• Present composition not for nuclearapplications; processing techniqueapplicable to reduced-activationcompositions

Klueh and Buck, J. Nucl. Mater. 283-287 (2000)

• Perspective• +50 year history

• Benefits• any desired combination of matrix

composition and dispersoid• significant improvements in high

temperature mechanical properties

• Problems• time-consuming & expensive• often produces materials with:

- anisotropic properties- coarse particles with non-uniform size

and spatial distribution

• joining and fabrication• lack of understanding - experiment,

theory, and modeling

Oxide Dispersion Strengthening ApproachFe-13Cr-3W-0.4Ti + 0.25Y2O3

Fe-9Cr-2W + 0.33TiO2 + 0.67Y2O3

Comparison of Tensile strength of New 12YWTNanocomposited Ferritic Steel vs. other ODS steels

0

200

400

600

800

1000

1200

400 600 800 1000 1200

Temperature K

12YWT

MA956

ODS (SUMITOMO)

9Cr-2WVTa

ODS(ZrO2)

ODS(TiO2)

ODS(MgO)ODS(Al

2O

3)

Str

es

s/M

Pa

Yield strength

Recently Developed Isotropic Oxide DispersionStrengthened Steels Offer Potential for Improved

Performance

• Thermal creep temperature limit for martensitic Fe-8Cr steel is ~550˚C (vs. >700˚Cfor several grades of ODS steel, including Kobe Fe-12Cr-3W-0.4Ti-0.25Y2O3)

0

50

100

150

200

250

300

350

10 100 1000 104 105

App

lied

Str

ess

(MP

a)

Rupture time (h)

650˚C

F82H(martensitic Fe-8Cr)

ODS Fe-11.5Cr(recrystallized ferrite)

0

50

100

150

200

250

300

350

400

450

22000 24000 26000 28000 30000 32000 34000 36000

12YWT9Cr-WMoVNb Steel12YMA957 (INCO)

LMP T(25+logt), (K-h)

Str

ess

(MP

a)

700°C, 530h, Stop

800°C, 931h, Stop

900°C, 1104h

800°C, 817h

650°C, 13000h

600°C, 17000h

650°C, 1080h, Rupt.

0

2

4

6

8

10

0 5,000 10,000 15,000

Str

ain

(%)

Time (h)

Nanocomposited 12YWT Ferritic Steel ExhibitsExcellent High Temperature Creep Strength

• Time to failure is increased by several orders of magnitude• Potential for increasing the upper operating temperature of iron

based alloys by ~200°C

800°C and 138 MPa- minimum creep rate

2.13 x 10-10s-1

- total strain2.03%

14,235h

Atom Probe Reveals the Presence of Nanoclustersin the Mechanically Alloyed 12YWT Ferritic Alloy

• Nano-size clusters– Average composition (at.%) :

O - 23.6 ± 10.6Ti - 19.9 ± 8.7Y - 9.2 ± 7.8

– Size : rg = 2.0 ± 0.8 nm– Number Density : nv = 1.4 x 1024/m3

• Original ~30 nm Y2O3 particles evolveto (Y,Ti,O) enriched nanoclusters

• Nanoclusters not present in ODS Fe-13Cr + 0.25Y2O3 alloy

Isocompositional Surface3-DAP Atomic Coordinates

Y Ti OCr

0

10

20

30

40

50

60

Cu-Ni-Be T-111 Nb-1Zr TZM V-4Cr-4Ti F82H F/M SiC/SiC

σU

TSK

th(1

- ν)/α

E

(kW

/m)

Ta-8W(1000˚C)

(800˚C) (600˚C) (800˚C)(200˚C)solutionized

& aged

steel(400˚C)

Mo-.5Ti-.1Zr(1000˚C)

q" crit =M (σth/σUTS)

∆x

Refractory Alloys

• Attractive Thermal/Physical Properties– high temperature capabilities

– thermal stress figure of merit

– liquid metal compatibility (Li)

0

20

40

60

80

100

0 500 1000 1500 2000

Podrezov et al 1987, 80%CWITER DDD 1998, as wroughtITER DDD 1998, rexl'dMarschall&Holden 1966, LT wrt+str.reliefMarschall&Holden 1966, LT rexl'dMutoh et al 1995, sintered Gumbsch et al 1998, single XtalBabak&Uskov 1984, powder met.

KQ

(M

Pa-

m1/

2 )

Temperature (˚C)

KC

• Main problems– low fracture toughness– low oxidation resistance– poor mechanical properties

of weldments

Recent research offers promise for developingrefractory alloys with improved ductility

• Controlled (50-1600 appm) additions of Zr, B, C to molybdenumincreases room temperature ductility of weldments from nearly zeroto etot~20% (M.K.Miller and A.J.Bryhan, 2001)

• Mechanically alloyed W-0.3wt%Ti-0.05wt%C (H. Kurishita et al.,ICFRM-10, Baden-Baden, Oct. 2001)– Avoid (W,Ti)2C brittle phase by limiting max concentration of carbon– Small grain size (~2 µm) helps to dilute harmful oxygen grain boundary

segregation– TiC dispersed particles provide increased toughness (appropriate fracture

mechanics tests needed to verify preliminary smooth bend bar results)

HAZ HAZWeldFracture occurred predominantly in

the heat affected zones

The fracture mode wastransgranular cleavagewith only small regionsof intergranular fracture.This contrasts theintergranular fracturetypically found incommercial Mo welds.

ALLOY COMPOSITION Zr 1600 appm C 96 appm B 53 appm O 250 appm N 178 appm Mo balance

MECHANICAL PROPERTIES Strain rate: 8.3x10-4 s-1

Mo- 30% Re filler

Ductility 19.5%Yield Stress 481 MPaUTS 544 MPa

Commercial Mo weld: 3% Ductility

Research performed byM. K. Miller, Oak Ridge National Laboratoryand A. J. Bryhan, Applied Materials

IMPROVEMENTS IN THE DUCTILITY OF MOLYBDENUM WELDMENTS BY ALLOYING ADDITIONS OF Zr, B and C

BASE METAL HEAT AFFECTED ZONE

ATOM PROBE TOMOGRAPHY REVEALSZr, B and C SEGREGATION TO THE GRAIN BOUNDARIES

Research performed byM. K. Miller, Oak Ridge National Laboratoryand A. J. Bryhan, Applied Materials

GIE (atoms m-2)Zr 7.6 x 1013

B 7.3 x 1012

C 1.1 x 1013

O -3.9 x 1012

GIE (atoms m-2)Zr 1.3 x 1013

B 9.9 x 1014

C 9.9 x 1011

O 1.1 x 1013

• Base metal: Zr, C and B enrichments and O depletion• HAZ: Heavy B and moderate Zr enrichments

FIM FIM

APT atom maps

Three-point bending stress-strain curves forpure tungsten and developed alloys A and B.

Example of the as-rolled sheets.

1

0

2

3

4

1

0

2

3

4

1

0

2

3

4

Stre

ss, σ

(GPa

)

Strain, ε (%) 10%

1

0

2

3

4

1

0

2

3

4

Pure W

Alloy A

Alloy B

473K

513K 583K

200K237K

278K375K

278K 324K 374K

200 300 400 500 600 7000

0.2

0.4

0.6

0.8

1

Abso

rbed

Ene

rgy

(J/m

m3)

?œAlloy A? W-0.2TiC (1999)?€Pure W

?œAlloy A? W-0.2TiC (1999)?€Pure W

Comparison of test temperature dependence of totalabsorbed energy and maximum strength among alloy A,W-0.2wt%TiC and pure tungsten (un-notched bend barimpact tests).

H. Kurishita et al., 2001

Mechanically alloyed W-0.3wt%Ti-0.05wt%Cexhibits good low temperature ductility

Comparison of Tensile (Red. in area) and CharpyImpact Ductile-Brittle Transition Behavior of Mo-0.5Ti

• The DBTT is dependent on numerous factors, including strain rate and notch acuity(“tensile DBTT” is not a meaningful design parameter)

0

20

40

60

80

100

0

30

60

90

120

150

-100 0 100 200 300 400

Red

uct

ion

in

Are

a (%

)

Imp

act

Str

eng

th (

ft-l

b)

Temperature (˚C)

Stress-relieved

Recrystallized

J.A. Houck, DMIC Report 140 (1960)

The fusion materials welding program has successfullyresolved one of the key feasibility issues for V alloys

– Results are applicable to other Group V refractory alloys (Nb, Ta)– Use of ultra-high purity weld wire may reduce atmospheric purity requirements

Success is due to simultaneous control of impurity pickup, grain size

-200

-100

0

100

200

300

1992 1994 1996 1998 2000 2002

DB

TT

(˚C

)

Year

V-4Cr-4Ti base metal

GTA welds (no heat treatment)

Motivation for pursuing Friction Stir Welding (FSW)

• A solid-state joining process such as FSW may enable field weldingof refractory alloys (V, Mo, W), due to reduced pickup ofatmospheric contaminants

• Irradiated materials with He contents above ~1 appm cannot befusion-welded due to cracking associated with He bubble growth;the lower temperatures associated with FSW may allow repairjoining of irradiated materials

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 0.5 1 1.5 2 2.5 3

Calculated size of He bubbles at grain boundaries in 316 SS

Dia

met

er (

µm)

Time (s)

1400 K

1500 K1600 K

Threshold He bubble size for cracking in 316 SS

Advanced materials can be successfully joined withfriction stir welding (FSW) process

• Friction stir welding (FSW)uses plastic deformation to joinmaterials.

– Homogeneous microstructureand properties are achieved.

– SiC fibers were uniformlydistributed.

Laser

FSW

Base Metal

Sponsor: DOE Office of Transportation TechnologiesOffice of Heavy Vehicle Technologies

• Metal matrix composites (MMC) and oxide dispersion strengthened (ODS) alloys aredifficult to join using conventional fusion welding processes.

– Particle / fiber reinforcement deteriorate in MMCs due to melting.– In Al-SiC MMC laser welds, SiC decomposes and forms Al4C3 carbides.

Silicon Carbide Composite Development

Silicon carbide composite is the least-developed of the 3 main structural materialsbeing studied in the Fusion Materials Program, but it has the greatest potential

Very Low Radioactivation - Very High Temperature Use

Areas being actively studied

• Radiation Hardened Composite Development• Effects of Helium on Mechanical Properties

• Radiation Degradation of Thermal Conductivity• Swelling, Amorphization and Defect Fundamentals

Matrix

Fiber

Interphase

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

No

rmal

ized

Str

ess

(S

irr/

Sa

ve)

Cross Head Displacement (mm)

UnirradiatedStress (MPA), S

aveFiber type

292 (3 tests)Regular Nicalon™359 (7 tests)Hi-Nicalon™416 (2 tests)Type-S Nicalon™

Type-S NicalonComposite

High NicalonComposite

Ceramic Grade Nicalon Composite10 mm

20 mm

2.3 x 6 x 30 mm

FCVI SiC Matrix, C-interphase, Plain Weave Composite~ 1 dpa, HFIR irradiation

ORNL / Kyoto U.

Development of Radiation-Resistant SiC Composites

Ceramic fiber 0.5 µm

SiC-interlayerThin C-interlayer

SiC-interlayer

Bulk SiC

Until recently, SiC/SiC composites exhibited significant degradation inmechanical properties due to non-SiC impurities in fibers causing interfacial debonding.

Upon irradiation, if fibers densify, fiber/matrix interfaces debonds

-->strength degrades300 nm

SiC fiber

SiC multilayersSiC multilayers

US/Monbusho “Jupiter” Program

We Now Have First Radiation-Resistant SiC Composite

Bend strength of irradiated“advanced” composites showno degradation up to 10 dpa

1st- and 2nd generationirradiated SiC/SiCcomposites show

large strength loss afterdoses >1 dpa

0

50

100

150

200

250

300

350

400

0 200 400 600 800

Th

erm

al C

ond

uct

ivit

y (W

/m-K

)

Temperature (C)

Type-S Composite (transverse)

P55 Graphite/CVI SiC (high TC)

Morton CVD SiC

K1100 Graphite/CVI SiC (high TC)

High Thermal Conductivity SiC/G Composites offerpotential for improved thermomechanical performance

Fiber K-1100 P-55 Nicalon Type-S

Kth (W/m-K@RT) ~950 120 15Diameter (micron) 10 10 13Tensile Strength (GPa) 3.1 1.9 2.6Tensile Modulus (GPa) 965 379 420Density (g/cc) 2.2 2.0 3.2

Predicted irradiatedconductivity ofSiC/G is higher

than monolithic SiC

Unirradiated

New Developments in SiC/SiC Fabrication:Nano-Powder Infiltration and Transient Eutectoid (NITE) Process

� Reinforcement� Tyranno™-SA grade-3 (Ube Industries, Ltd.)� Uni-directional� PyC coating, 800nm-thick nominal

� Transient eutectoid process� Uni-axial hot-pressing� Tp ≤ 1800°C� Pp ≤ 20MPa

� Matrix raw materials� Beta-SiC Nano-powder (110m2/g) and

submicron (~40m2/g) powders� Al2O3-Y2O3 complex as sintering additive� Pre-ceramic polymer inclusion

for intra-bundle densification

Institute of Advanced Energy, Kyoto University

ArP

P

preceramicpyrolysis

Carbon coated TyrannoSA fiber tows

Pre-formingthrough winding

Pre-treatmentby PIP

Matrix coatingby mixed slurry

Drying andstacking

Hot pressing

Characterization

Flow Chart of the “NITE” ProcessInstitute of Advanced Energy, Kyoto University

“NITE”-Fabricated SiC/SiC

1780C/20MPa

10um


Microstructure of “NITE”-Fabricated SiC/SiC

Tyranno™-SA

SiC Matrix

PyC Interphase


Fabrication Cost of SiC/SiC by Various Processes

Production cost (k$/kg)

Tota

l Per

form

ance

10

CVI(Mass-Prod.)

10.1

Fiber costAs of Yr.2001Tyranno™-SA

EstimatedMass-production

Fiber costTyranno™-SA

Adv.PIP(Mass-prod.)

Adv.RS/MI (Mass-prod.)

NITEMass-prod.

Fiber cost As of Yr.2001Nicalon™-CG

Adv. RS/MI(Lab-grade)

NITE(Kyoto U.)

PIPConventional

RS/MIConventional

CVIConventional

CVI(Lab-grade)


1 03 1 04 1 051 0-5

1 0-4

(b)Flat SiC/SiC composites

F-2

F-1

Pdow

n

Pupper

LPS-2

Tubes by LPS (Kyoto University)

1 03 1 04 1 05

1 0-2

1 0-1

1 00(a) Cylindrical SiC/SiC composites

C-3

C-2

C-1

Pdow

n

Pupper

PIP

PIP+MI

Tyrannohex

Conventional SiC/SiC and Bonded-SiC-Fiber Ceramics

NITE

Permeability of He in SiC/SiCInstitute of Advanced Energy, Kyoto University

CVI-SiC/SiC

Comparison of Thermal Conductivity of SiC/SiC

0

5

10

15

20

25

30

35

40

0 200 400 600 800 1000 1200 1400

Temperature / C

The

rmal

con

duct

ivity

/ W

/m-K

TySA/PyC/NITE-SiC (1780/20)

TySA/PyC/NITE-SiC (1800/15)

Monolithic-SiC (1780/15*)


Mechanical behavior of a wide range of copper alloys hasbeen investigated vs. strain rate and temperature(constitutive equations for deformation and fracture)

0

50

100

150

200

250

0 100 200 300Fra

ctu

re T

ou

gh

nes

s, K

JQ (

MP

a-m

1/2)


CuCrZr

Cu-Al2O3

CuNiBe

CuCrNb

L-T orientation

0

100

200

300

400

500

600

700

800

0 200 400 600 800

Ult

imat

e T

ensi

le S

tren

gth

(M

Pa)

Temperature (˚C)

CuCrZr, ITER SAA

CuNiBe, HT1 temper

CuNiBe, AT

GlidCop Al25 (IG0)

1-2x10- 3 s- 1

CuCrNb

• CuNiBe has superior properties below 100˚C; CuCrZr and Cu-Al2O3 have best properties at intermediate temperatures• high temperature limits in CuNiBe and Cu-Al2O3 alloys areassociated with grain boundary phenomena

0

100

200

300

400

500

600

700

800

0 200 400 600 800

Ult

imat

e T

ensi

le S

tren

gth

(M

Pa)

Temperature (˚C)

CuCrZr, ITER SAA

CuNiBe, HT1 temper

CuNiBe, AT

GlidCop Al25 (IG0)

1-2x10- 3 s- 1

CuCrNb

1 0- 6

1 0- 5

0.0001

0.001

0.01

0.1

0 0.2 0.4 0.6 0.8 1

Deformation Map for CuNiBe (Brush-Wellman Hycon 3HP)

No

rmal

ized

Sh

ear

Str

ess,

τ/µ

(20

˚C)

Normalized Temperature, T/TM

Elastic regime( dε/dt<10-8 s-1)

Coble creep

Dislocation creep

Dislocation glide

Theoretical shear stress limit

20 ˚C 300 ˚C 500 ˚C

1 4

1 4 0

Un

iaxi

al T

ensi

le S

tres

s, M

Pa

1 . 4

1 4 0 0

1 0-8 s-1, L=30 µm

N-H creep

1 0- 6

1 0- 5

0.0001

0.001

0.01

0.1

0 0.2 0.4 0.6 0.8 1

Deformation Map for Oxide Dispersion-strengthened Copper (GlidCop Al25)

No

rmal

ized

Sh

ear

Str

ess,

τ/µ

(20

˚C)

Normalized Temperature, T/TM

Elastic regime( dε/dt<10-8 s-1) Coble creep

Dislocation creep

Dislocation glide

Theoretical shear stress limit

20 ˚C 300 ˚C 500 ˚C

1 4

1 4 0

Un

iaxi

al T

ensi

le S

tres

s, M

Pa

1 . 4

1 4 0 0

1 0-8 s-1, L=5 µm

N-H creep

Applications to US industry (e.g.,USCAR) as well as fusion energysciences program

Mechanical behavior of copper alloys can be understood onthe basis of current materials science models of deformation

Fiber Type Supplier Remarkscore clad.

Diameter(µm)

RF

JPN

KS-4V

KU-1

KU-H2G

F F

M F

FORC

FORC

FORC

Fujikura Ltd.

MitsubishiCable

200 250

200

200

200

200

250

250

250

250

Pure silica core, OH & Cl free

Original, OH:800ppm

Improved, Hydrogen treatedOH:800ppm

Fluorine doped silica core,OH-free

Fluorine doped silica core,OH-free

Optical fibers for ITER round robin irradiation tests

Team

T. Kakuta et al., ICFRM11 (2001)

400 600 800 1000 1200 1400 1600

KU-H2GKU-1KS-4VMFFF

Induced Loss (dB

Wavelength (nm)

Comparison of increased absorption in ITER round robin fibers at gamma-ray irradiation of 1.9e6 Gy.

Irrad. source : Cobalt-60 gamma-rayExposure dose : 1.9e6 Gy

Fiber type

0

1.0

2.0

3.0


-10

0

10

20

30

40

400 600 800 1000 1200 1400 1600

KS:5.7e20KS:1.0e22KU:5.7e20KU:1.0e22KH:5.7e20KH:1.0e22FF:5.7e20FF:1.0e22MF:5.7e20MF:1.0e22

Induced Loss

Wavelength (nm)

1.0e22 n/m2

5.7e20 n/m2


Observed Absorption of Optical FibersDuring Fission Neutron Irradiation

High loss in MF fiber may be due to neutron radiation-induced microcracking

Conclusions

• There is a strong prospect for improvements in the capabilities offusion structural materials based on ongoing research– Nanocomposited ferritic steels– Ductile Mo and W alloys– Hermetic, high conductivity, radiation-resistant, lower cost SiC composites

• Improved joining techniques are being applied to fusion materials– Gas tungsten arc welding of V alloys– Friction stir welding

• Materials which can be categorized as “reduced-activation” haveproperties comparable or superior to their commercial (high-activation) counterparts– e.g., Fe-9Cr ferritic/martensitic steels developed for fusion

• Additional screening studies are needed to identify the mostpromising nonstructural materials for fusion (organic insulators,optical materials, etc.)

advanced materials for fusion technologyadvanced materials for fusion technology s.j. zinkle1 and a....

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