ORNL is managed by UT-Battelle for the US Department of Energy

Effects of Neutron Irradiation in IG-110

Y. Katoh, M. Snead, A.A. CampbellOak Ridge National Laboratory

E. Kunimoto, M. Yamaji, T. KonishiToyo Tanso Co., Ltd.

Presented at the 15th International Nuclear Graphite Specialist Meeting (INGSM-15), September 15-18, 2014, Hangzhou, China

DisclaimerAll data included in this presentation are preliminary and are subject to revision after further analysis and

certification processes are complete.

2 Toyo Program Update

Acknowledgements

• Research sponsored by Toyo Tanso Co., Ltd. under contract NFE-10-02974 with UT-Battelle, LLC.

• Use of HFIR sponsored by Office of Basic Energy Science, U.S. Department of Energy.

• Patricia Tedder, William Comings, Stephanie Curlin, Michael McAllister, Daniel Lewis, Brian Eckhart, Chunghao Shih, Wallace Porter, Marie Williams for their work in LAMDA to obtain the presented results. Nesrin Cetiner and Joel McDuffee for irradiation engineering. Additional ORNL people for irradiation management, hot cell work, radiological protection, etc.

3 Toyo Program Update

Program Summary

• Temperature range significant for gas cooled reactors (300°C-1000°C)

• Dose range from 7 – 40 n/m2 (x1025 [E>0.1MeV])(5 – 30 dpa)

• Acquire comprehensive design properties by rabbit and target creep irradiations

• Rabbit program– PIE-1 is complete – early results reported here

– PIE-2 is in process

– PIE-3 planned after spring 2015

• Creep program– PIE-1 in late 2014 through 2015

– PIE-2 in ~2017

4 Toyo Program Update

Pre-Irradiation Material Properties

IG-110a IG-110 ORNL IG-430a IG-430 ORNL

Density (g/cm3) 1.77 1.77 1.82 1.81

Young’s Modulus (GPa) 9.8 9.10 AX9.69 TR 10.8 10.61 AX

11.24 TR

Young’s (Sonic Velocity) 8.94 AX9.75 TR

9.80 AX10.56 TR

CTEmean (x10-6/°C) 4.5b 4.305 Axc

4.069 TRc 4.8b 4.277 AXc

4.079 TRc

Thermal Conductivity (W/m/K) 120 129.04 AX

130.39 TR 140 161.01 AX162.81 TR

Compressive Strength (MPa) 78 79.16 AX

77.71 TR 90 84.93 AX87.32 TR

Tensile Strength (MPa) 25 37

Flexural Strength (MPa) 39d 33.55 AXe

35.87 TRe 54d 46.94 AXe

50.50 TRe

a： Catalog valueb： The measurement temperature range for the CTE is 350 to 450℃c： The measurement temperature range for the CTE is RT to 400℃d： 3 point loadinge： 4 point loading

5 Toyo Program Update

Definition of Orientations for Iso-molded Graphite

X = (~with grain) = against gravity = transverse (TR)

Y = (~with grain) = against gravity = transverse (TR)

Z = (~against grain) = with gravity = axial (AX)

6 Toyo Program Update

Specimen Shapes and Orientations

+Z(AX)

+Y(TR)

-X(TR)

25=L

3=W

2.9=T

MB (TR)

Y=8

Z=X=6

CRS (TR)

Y=4

Z=X=6

TD4 (TR)

25=L

3=W

2.9=

T

MB (AX)

CRS (AX)

Z=8

X=Y=6

TD4 (AX)

4=Z

X=Y=6

TD3 (AX)

3=Z

X=Y=6

Y=3

Z=X=6

TD3 (TR)

Validation of small specimen testing in Y. Katoh et al., ASTM STP1578 (in press)

7 Toyo Program Update

Specimen Arrangement in Rabbits

• Two capsule types

• 25 capsules with 8 modulus beam specimens in each capsule

• 9 capsules with a combination of compression strength and thermal diffusivity specimens

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Irradiation Envelope

5 10 15 20 25 30 35 400

200

400

600

800

1000

1200 TTB PIE-1

TTB PIE-2

TTB PIE-3

TTR PIE-2

TTR PIE-3

Neutron Fluence (x1025 n/m2 [E>0.1MeV])

Irra

dia

tion

Tem

per

atu

re (

°C)

9 Toyo Program Update

Creep Capsule Specimens

+Z(AX)

+Y(TR)

-X(TR)

CRS (AX) TD3 (AX)

Z=83=Z

X=Y=6

X=Y=6

Y=8 Y=3

Z=X=6Z=X=6

CRS (TR) TD3 (TR)

CRP (AX)

Z=8

X=Y=6

Y=8

Z=X=6

CRP (TR)

1.25 mm hole down center

1.25 mm hole down center

10 Toyo Program Update

Creep Capsule Design

• Loaded region has 4 CRP specimens and 1 CRS specimen in each temperature zone

• Lower unloaded region has 1 CRS specimen, 2 CRP specimens, and 8 TD3 specimens in each temperature zone

Upper stressedregion

Lowerunstressedregion

300°C

450°C

600°C

600°C

450°C

300°C

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5 10 15 20 25 30 35 400

200

400

600

800

1000

1200 TTB PIE-1

TTB PIE-2

TTB PIE-3

TTR PIE-2

TTR PIE-3

Neutron Fluence (x1025 n/m2 [E>0.1MeV])

Irra

dia

tion

Tem

per

atu

re (

°C)

Irradiation Envelope

12 Toyo Program Update

Data Analysis Notes

• In the following plots a consistent color and plotting scheme is used:– Filled data points and solid lines are AX direction– Open data points and dotted lines are TR direction– Error bars are one standard deviation (data points without

error bars are measurements from one specimen)– In plot legends the IG-110 is only listed by average

temperature, which IG-430 has the material label included– Data point shapes and color family were kept the same

for IG-110 and IG-430 (i.e. 319°C IG-110 red circles and IG-430 are pink circles)

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Dimensional Change

Burchell, HTK-7 Experiment

14 Toyo Program Update

Volume Change

Ishiyama et al. (1996)

15 Toyo Program Update

Young’s Modulus Change

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Compressive Strength IG-110

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Thermal Conductivity

650°C

1021.0~,

11

,

1 KmWTKKTK RDunirrirr

Ishiyama et al. (1996)

18 Toyo Program Update

CTE of Irradiated IG-110

Mean CTE referenced to Room Temperature

19 Toyo Program Update

CTE Changes with Neutron Fluence

Mean CTE referenced to Room TemperatureCTE values at irradiation temperature

20 Toyo Program Update

Irradiated Young’s Modulus Change Correlates with Density Change

28.4

00

EE

• Irradiated Young’s modulus correlates very well with density (and electrical conductivity).

• Density exponent for irradiation-induced modulus changes appears significantly greater than that for oxidation-induced modulus decrease.

• Large (>> 1) density exponent indicates that pores responsible for modulus variations are extremely non-spherical.

Yoda et al. (1985)

Kunimoto et al. (2009)

Schulz (1981)

Field

EllipsoidalPore

FF

p

2

cos

1

cos1

122

Transfer efficiency factor:

a

F 0 F = 1/3 F 1

21 Toyo Program Update

Major Change in Structural Factor Requires Refinement of Defect Thermal Resistivity Model

0

0 ,,,

unirrunirrunirr

irrirrirr

KK

TKTTK

e : transport efficiency factor in porous medium

000irr

irr

irr

irr

irr

irrirr E

E

K

K

K0 : thermal conductivity of pore-free bulk

unirr

unirr

irr

irr

unirrirrRD KTKKTKTK

,

1

,

1

,

1000

1/K0RD : intrinsic radiation defect thermal resistivity

= better measure of matrix defect accumulation

unirrirrRD KTKTK

1

,

1

,

1

1/KRD : radiation defect thermal resistivity in conventional model

22 Toyo Program Update

Summary

• PIE-1 campaign is in progress

• Initial results show expected trends– All observations consistent with each other and known trends in

early contraction regime– Observed difference in dimensional behavior depending on axial or

transverse relation to gravity during molding

• Findings / implications from additional analyses– Structural term dominates in modulus change in this dose range

• Source mainly from crack closure

– Decrease in intrinsic thermal conductivity more significant than in apparent conductivity

• More PIE-1 and PIE-2 results to come– Higher fluence– Higher temperatures