The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Tim Burchell, Joel McDuffee and Ken Thoms Oak Ridge National Laboratory ASTM Symposium on Graphite Testing for Nuclear Applications: The Significance of Test Specimen Volume and Geometry and the Statistical Significance of Test Specimen Population

2Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Overview of Presentation Objectives Introduction – HTV Capsule Experimental – Materials and Test Condition – Experimental Methods/Test Techniques Results & Discussion Conclusions

3Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Acknowledgments This work is sponsored by the U.S. Department of Energy, Office of Nuclear Energy Science and Technology under contact DE-AC05-00OR22725 with Oak Ridge National Laboratories managed by UT-Battelle, LLC. Use of the High Flux Isotope Reactor at the Oak Ridge National Laboratory was supported by the U.S Department of Energy.

4Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Objectives The primary objective of the High Flux Isotope Reactor, Target, Very High Temperature Reactor (HTV) irradiation capsule is to provide high- temperature irradiation dimensional change data to support the design of the high-temperature (1200°C) Advance Graphite Creep (AGC) experiment being planned for the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL)

5Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule The Pre-Irradiation Examination (Pre-IE) data are reported here for each grade of graphite in the HTV capsule and include: Dimensions, mass, volume, and density Elastic Modulus (E dym ) from sonic velocity

6Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Introduction

7Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule The HTV Capsule A HFIR target rod capsule Two cycles to a peak dose of 3.17 displacements per atom (DPA) The capsule has multiple temperature zones allowing nominal design irradiation temperatures of 900, 1200, and 1500°C. 8 sub-capsules each with 9 specimens, total = 72 6 nuclear graphite grades

8Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule The HTV Capsule

9Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Experimental

10Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Materials and Test Conditions Graphite Grade SourceCountry of Origin Process Details NBG-17 SGL CarbonGermany/France Pitch coke, vibrationally molded, medium grain NBG-18 SGL CarbonGermany/France Pitch coke, vibrationally molded, medium grain H-451 (Reference Grade) SGL CarbonUSA Petroleum coke, extruded, medium grain No longer in production PCEA GrafTech International USA Petroleum coke, extruded, medium grain IG-110 Toyo TansoJapan Petroleum coke, isostatically molded, fine grain 2114MersenUSANonpetroleum coke, isostatically molded, super fine grain

11Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule HTV graphite specimens from larger blocks/billets Unique numbering system provide record of oreintation and a reference mark on the specimen For each grade there are three specimen sizes according to the temperature zone in which the specimens are located. The exact specimen dimensions and tolerances are given in ORNL drawing number X3E020977A562 Rev. 0, parts 24, 25, and 26

12Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule

13Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule

14Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule

15Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Experimental Methods/Test Techniques

16Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Bulk Density ASTM C (Reapproved 2010) ), Standard Test Method for Bulk Density by Physical Measurement of Manufactured Carbon and Graphite Articles The specimen dimensions were measured using a Mitutoyo Micrometer, 0-1", ID# and a Mitutoyo Digital indicator,0- 1", for the Dyer Small Hole Gage The Mass of the specimens was measured using a Sartorius Micro Balance, Model M235S

17Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Dimensional measurement scheme

18Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Young Modulus The dynamic Young’s Modulus was determined by the time-of- flight/ultrasonic velocity method according to ASTM C Panametric (Olympus) signal generator National Instrument oscilloscope interface Panametric (Olympus) 2.25 MHz frequency Specimen holder with constant force Sonotech gel coupling

19Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Ultrasonic velocity

20Managed by UT-Battelle for the U.S. Department of Energy Ultrasonic velocity The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule

21Managed by UT-Battelle for the U.S. Department of Energy Ultrasonic velocity The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule

22Managed by UT-Battelle for the U.S. Department of Energy Ultrasonic velocity The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule

23Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Results and Discussion

24Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule

25Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Bulk Density seen to increase over diameter (volume) range studied Diameter range extended by addition of AGC-1 specimen data Observation related to surface roughness Specimens (lathe) turned Surface pull out of filler particles, therefore a link between filler particle size and observed data trend Micrometer used for dimensional measurement dad a constant force (clutch) mechanism We shall use relative dimensional/density changes, not absolute values

26Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule

27Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Observed a reduction of dynamic elastic modulus Trend extended with the addition of AGC-1 specimens HTV 0.9 E (per ASTM standard), AGC-1 is ν corrected The reduction of E is unexpected since the density is seen to increase with volume, and E = ρ x v 2 Hence decrease in velocity 2 term is larger than increase in density E effect most marked in coarser textured graphites

28Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule ASTM C769 cautions when wavelength is commensurate with filler particle size dimensions the TOF (velocity) data may be erroneous Probe frequency was 2.25 MHz, λ = c/f, ~ 1.2 mm NBG-18 FP size =1.6 mm (max) NBG-17 FP= 0.8 mm (max) PCEA FP= 0.8 mm (max) H-451 FP= 0.5 mm (mean) Shall use fractional change of modulus on irradiation

29Managed by UT-Battelle for the U.S. Department of Energy The Pre-Irradiation Examination of Small Specimens for a High Temperature HFIR Irradiation Capsule Conclusions Reported Pre IE data for HTV specimens Significant trends observed in the data as a function of specimen diameter or volume (constant thickness) – Increases in bulk density – Reduction in dynamic Young’s modulus Observed trends appear to be texture related (filler particle size) For HTV we can use the in the factional change in properties Demonstrates the need for guidance related to specimen volume and filler particle size