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. Campbell Oak Ridge National Laboratory E. Kunimoto, M. Yamaji, T. Konishi Toyo Tanso Co., Ltd. Presented at the 15 th International Nuclear Graphite Specialist Meeting (INGSM-15), September 15-18, 2014, Hangzhou, China Disclaimer All 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 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/m 2 (x10 25 [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-110 a IG-110 ORNLIG-430 a IG-430 ORNL Density (g/cm 3 ) Young’s Modulus (GPa) AX 9.69 TR AX TR Young’s (Sonic Velocity) 8.94 AX 9.75 TR 9.80 AX TR CTE mean (x10 -6 /°C)4.5 b Ax c TR c 4.8 b AX c TR c Thermal Conductivity (W/m/K) AX TR AX TR Compressive Strength (MPa) AX TR AX TR Tensile Strength (MPa)2537 Flexural Strength (MPa)39 d AX e TR e 54 d AX e TR e a ： Catalog value b ： 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 loading e ： 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

8 Toyo Program Update Irradiation Envelope

9 Toyo Program Update Creep Capsule Specimens +Z(AX) +Y(TR) -X(TR) CRS (AX) TD3 (AX) Z=8 3=Z X=Y=6 Y=8 Y=3 Z=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

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 stressed region Lower unstressed region 300°C 450°C 600°C 450°C 300°C

11 Toyo Program Update 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)

13 Toyo Program Update Dimensional Change Burchell, HTK-7 Experiment

14 Toyo Program Update Volume Change Ishiyama et al. (1996)

15 Toyo Program Update Young’s Modulus Change

16 Toyo Program Update Compressive Strength IG-110

17 Toyo Program Update Thermal Conductivity 650°C 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 Temperature CTE values at irradiation temperature

20 Toyo Program Update Irradiated Young’s Modulus Change Correlates with Density Change 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 Ellipsoidal Pore Transfer efficiency factor:  F  0F = 1/3F  1

21 Toyo Program Update Major Change in Structural Factor Requires Refinement of Defect Thermal Resistivity Model  : transport efficiency factor in porous medium K 0 : thermal conductivity of pore-free bulk 1/K 0 RD : intrinsic radiation defect thermal resistivity = better measure of matrix defect accumulation 1/K RD : 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