The AGC-1 Creep Experiment - Results and Analysis INGSM-15 HANGZHOU, CHINA Sept 15-18, 2015 Tim Burchell Fusion Materials & Nuclear Structures Group Materials Science & Tech. Division and Will Windes Idaho National Laboratory

2Managed by UT-Battelle for the U.S. Department of Energy Acknowledgements This work is sponsored by the U.S. Department of Energy, Office of Nuclear Energy Science and Technology under contract DE-AC05-00OR22725 with Oak Ridge National Laboratory, managed by UT-Battelle, LLC. The author wishes to acknowledge the contributions of Ashli Clark (ORNL)

3Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment Outline of Presentation The AGC Graphite Creep Experiment The AGC-1 Graphite Creep Capsule AGC-1 Graphite Graphites & Specimens Graphite Post Irradiation Examination (PIE) Testing Creep Strain Analysis (all data analyzed, no data rejected) Comparison with H-451 and IG-110 ”historical” data for dimensions & volume change Creep Coefficient, K Other Grades in AGC-1: NBG17; NBG-18; PCEA; IG-430 Dimensions Creep Coefficient, K Comparison of second stage creep coefficients, K, for the various grades examined with literature data KE 0 Comparison for all six grades in AGC-1 Conclusions

4Managed by UT-Battelle for the U.S. Department of Energy The AGC Graphite Creep Experiment The AGC Creep experiment comprises six ATR irradiation capsules that shall provide data over the reactor design envelope AGC-1 was the first of these capsules (prototype) and shall provide design data (at T irr ~ 600°C) on: o Effect of neutron Irradiation on the dimensions and key physical properties of graphite o Graphite creep strain and creep rate data o Effect of neutron Irradiation induced creep strain on key physical properties of graphite

5Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Capsule Experimental Variables (Creep/Control Specimen) Specimen Orientation: WG/AG Graphite Grades: NBG-18, NBG-17, H-451, PCEA, IG-110, IG-430 Irradiation Dose Range: 2.8 – 6.9 DPA o Measured with flux wires Irradiation Temperature Range: Approximately °C o Measured with TC’s and SiC temperature monitors Applied Stress (nominal): o 2 2 ksi (13.8 MPa) o ksi (17.3 MPa) o 2 3 ksi (20.7 MPa)

6Managed by UT-Battelle for the U.S. Department of Energy The AGC Graphite Creep Experiment The major Grades in the AGC series* Graphite GradeForming MethodIntended PurposeAGC Code Letter NBG-17Vibrational moldedAREVA NGNP DesignA NBG-18Vibrational moldedPBMR (not currently being pursued)B H-451ExtrudedHistorical Grade (REF)C PCEAExtrudedAREVA NGNP DesignD IG-110Isostatically Pressed PMBR-DM (China) – Under construction E IG-430Isostatically PressedCandidate GraphiteF *GRADE 2114 (MERCEN) ADDED IN AGC-2 ONWARDS Specimen quantities: NBG-17 = 34; NBG-18 = 34; H-451 (Reference Grade) = 20; PCEA = 34; IG-110 (Reference Grade) = 20; IG-430 =32. Total = 174 SPECIMENS

7Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment

8Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment

9Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment Transient Creep Steady State or “Linear” Creep

10Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment Creep and Control Specimen Volume Change Similar (especially at lower doses). All six graphites observed to have similar creep and control volume change curves! CREEP AT CONSTANT VOLUME

11Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment H-451 dimensional change,% Specimen Length (WG) Specimen Diameter (AG)

12Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment Longitudinal (WG) creep strain plots for grade H-451 Normalized creep strain (WG) Coefficient, K = %/DPA·MPa or x cm 2 /n·Pa

13Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment

14Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment

15Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment Creep coefficients summary GradeCode Secondary creep strain coefficient,K, %/DPA.MPa Total creep strain coefficient micron/DPA Creep strain Ratio Secondary creep strain coefficient, K, cm 2 /n.Pa LongitudinalLateralLongitudinalLateral LongitudinalLateral NBG-17A NGB-18B H-451C PCEAD IG-110E IG-430F

16Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment

17Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment H-451 total creep strain in microns Creep strain ratio = Ɛ (lat)/ Ɛ (long) = (18.11/ ) = -0.18

18Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment Mean ± 1Standard Deviation H-451 Poisson's Ratio (unirradiated), ν = ± 0.01 H-451 Poisson's Ratio (irradiated unstressed or control specimen), ν irr = ± 0.03 H-451 Poisson's Ratio (irradiated stressed or crept specimens), ν irr = ± 0.04 H-451 Creep strain ratio Ɛ C(lat) / Ɛ C(long) = -0.18

19Managed by UT-Battelle for the U.S. Department of Energy A Comparison of Poisson's Ratio (irradiated and Unirradiated and The Creep Strain Ratio for the Six Graphites in AGC-1 Graphite Grade Grade Letter Piosson's Ratio Creep Strain Ratio UnirradiatedControlCreep NBG-17A NGB-18B H-451C PCEAD IG-110E IG-430F The AGC-1 Graphite Creep Experiment

20Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment NBG-17 and IG-430 ARE SUSPECT!

21Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment CONCLUSIONS 1.The AGC-1 creep capsule has completed its irradiation, it has been dismantled, the specimens & T monitors shipped to ORNL. PIE (except strength testing) has been completed. 2.Grades NBG-17, NBG-18, H-451, PCEA, IG-110 and IG-430 were examined 3.Initial analysis of dimensional change and creep strain data for all graphites completed 4.Thermal design/control/operation of AGC-1 was not optimal and made the analysis more challenging 5.The dimensional behavior of H-451 and IG-110 compare favorably with previous data 6.The volume change behavior of the creep and control samples were seen to be similar, especially at lower doses, for all six grades 7.The creep strain data are linear and lend themselves to analysis using the simple “linear” creep law.

22Managed by UT-Battelle for the U.S. Department of Energy The AGC-1 Graphite Creep Experiment CONCLUSIONS (continued) 8.Creep strain was normalized to applied stress and plotted against dose, creep strain data falls on common line 9.The use of the linear creep model is justified at the low doses encountered in AGC-1 10.K for all graphites compares favorably with literature data 11.Comparing K.E 0 for all six graphites (longitudinal and lateral) revealed NBG- 17 and IG-430 data to be suspect Next Steps: Eliminate dimensional/creep data from AGC-1 analysis where T irr >500°C but 100°C