- TEM investigation of irradiation, irradiation creep and thermal annealing effects in nuclear graphite

Principal Investigator
Name:
Jose D Arrregui-Mena
Email:
[email protected]
Phone:
(208) 526-6918
Team Members:
Name: Institution: Expertise: Status:
Denise Adorno Lopes
Theodore Besmann
José David Arregui-Mena Oak Ridge National Laboratory J. David Arregui Mena is a post-doctoral researcher in Nuclear Materials Science and Technology group at Oak Ridge National Laboratory where he is developing new techniques to measure the effects of irradiation in the microstructure of graphite. He is also investigating other carbon base materials such as SiC and carbon fiber composites. Other
Timothy Burchell Oak Ridge National Laboratory Dr. Tim Burchell is Distinguished R&D staff member and Nuclear Graphite Team Leader in the Nuclear Materials Science and Technology Group within the Materials Science and Technology Division of the Oak Ridge National Laboratory (ORNL). He is engaged in the development and characterization of carbon and graphite materials for the U.S. Department of Energy. Prior to assuming his current position he was the Carbon Materials Technology (CMT) Group Leader and was manager of the Modular High Temperature Gas-Cooled Reactor Graphite Program where he was responsible for Other
Philip Edmondson Oak Ridge National Laboratory Philip Edmondson is Radiation Effects Characterization Team Leader in the Nuclear Materials Science and Technology Group at ORNL in which he uses techniques such as advanced electron microscopy and atom probe tomography to characterize radiation effects in metals, ceramics and composites. Prior to this, he was an Engineering and Physical Sciences Research Council (EPSRC) Career Acceleration Fellow at Oxford University (UK) specializing in the characterization of radiation effects in materials. He has published approximately 60 papers on radiation effects in materials and is an Associate Editor of the journal Nuclear Materials and Energy. Other
Experiment Details:
Experiment Title:
TEM investigation of irradiation, irradiation creep and thermal annealing effects in nuclear graphite)
Work Description:
The PCEA graphite specimens are part of the Advanced Graphite Creep-1 (AGC-1), the irradiation conditions are: An unirradiated sample, 2 crept irradiated samples (4.36 and 5.66 dpa irradiated at a temperature of 606°C and 669 °C respectively) and 2 uncrept irradiated samples (3.91 and 5.02 dpa irradiated at a temperature of 533°C and 585 °C respectively). High magnification and atomic resolution TEM images will be used to characterize microstructure evolution of graphite under irradiation as well as crystal lattice defects. Moreover, the post-annealing imaging will be performed to identify the temperatures at which the recovery process starts. Diffraction patterns will be used to quantify the crystallinity of the samples at each stage of irradiation and annealing condition.
Project Summary
The Advanced Graphite Creep-1 (AGC-1) program was developed to qualify six types (NBG-18, NBG-17, H-451, PCEA, IG110, IG-430) of graphite grades for their use in Gen IV nuclear reactor designs or to produce a reference database. The irradiation and creep conditions were performed at a similar range of temperatures and dose as a Gen IV graphite reactor core. The atomic-level and microstructure data of graphite under this irradiation conditions are scarce, limiting the understanding between the irradiation defects and bulk material properties. This research selected samples irradiated at different stages of irradiation and creep to understand the mechanisms that alter the microstructure and crystal lattice of graphite.



PCEA graphite samples will be used to determine the atomic-level structure, microstructural and irradiation defects of 7 samples. A unirradiated sample, 2 crept irradiated samples (4.36 and 5.66 dpa at a temperature of 606°C and 669 °C respectively) and 2 uncrept irradiated samples (3.91 and 5.02 dpa at a nominal temperature of 533°C and 585 °C) were selected for this study. SEM and TEM imaging will be used to characterize the different microstructures and types of defects found in each sample. Moreover, an in-situ annealing of the graphite specimens will be performed (1200°C) to understand the annealing effects on each specimen.

Relevance
The proposed study will characterize the microstructural changes and defects produced by irradiation and creep on graphite. TEM and SEM images will provide atomic and microstructure information that will improve the understanding of irradiated graphite. Furthermore, a novel study of annealing of irradiated graphite will improve the investigations of irradiation damage on graphite. This will allow other investigators to validate simulations based on the micromechanistic response of irradiated graphite for US Very Hight Temperature Reactors and Molten Salt Reactors.