Materials in Nuclear Energy Systems (MiNES) 2021: Poster Session
Program Organizers: Todd Allen, University of Michigan; Clarissa Yablinsky, Los Alamos National Laboratory; Anne Campbell, Oak Ridge National Laboratory

Tuesday 5:30 PM
November 9, 2021
Room: Sky
Location: Omni William Penn Hotel


Quantifying the Impact of an Electronic Drag Force on Defect Production from High-Energy Displacement Cascades in α-zirconium: Jose March-Rico1; C. McSwain1; Brian Wirth1; 1University of Tennessee, Knoxville
    Defect production following displacement cascades with PKA energies up to 40 keV is compared between two conditions in α-zirconium: 1) considering only nuclear stopping effects and 2) considering simultaneous nuclear and electronic stopping. Electronic energy losses are implemented as a drag force with strength proportional to the energy-dependent stopping power as predicted by SRIM calculations. This adjustment is performed using a new and user-friendly command, “fix electron/stopping”, innately available in the LAMMPS software. We find that electronic energy losses result in a 10 – 20 % reduction in the surviving damage produced by high-energy PKAs, and this should be accounted for when considering defect generation rates in mesoscale codes. This method of electronic energy loss implementation predicts nuclear damage energies that are comparable with the SRIM-predicted values when using the full-cascade TRIM calculation, as has recently been recommended to the community.

Cancelled
Evaluation of Water Degradation in Medium Voltage Electric Cables Found in Nuclear Power Plants: Sean O'Brien1; Brian Hinderliter1; Margaret Elmer-Dixon1; 1University of Minnesota Duluth
    Nuclear power plants use medium-voltage cables to power numerous safety components. Although some are used only in emergency situations, these cables have the same reliability requirements as other cables used in active plant components, and therefore are tested regularly. Testing typically occurs under normal operating conditions and thus does not account for potential water immersion due to accident conditions. Water immersion can lead to a phenomenon called water treeing in regions of the insulation, which over time will permanently degrade the insulation and may lead to cable failure. To better understand water treeing in EPR-insulated cables, finite element analysis was used to simulate various water tree conditions. Specific energy absorption rate (SAR), a measure of insulation degradation rate, was determined at locations along a water tree’s growth path to establish when degradation reaches cable failure. Additionally, SAR is directly correlated with a temperature rise, further synergistically increasing the failure rate.

Design of a Test System for Hot Hydrogen-facing Components in Nuclear Thermal Propulsion Systems: William Searight1; Leigh Winfrey2; 1 Pennsylvania State University; 2Pennsylvania State University
     Nuclear thermal propulsion is a promising candidate for deep-space crewed missions to Mars given their improved performance over chemical rockets. A pressing issue in NTP development is the testing of high-temperature components at prototypical conditions. To evaluate material performance of moderator elements, a hot hydrogen test loop, capable of producing circulating hydrogen at temperatures up to 1200 °C, is under construction at Penn State. This work details the test loop design and development informed by Ansys Fluent to simulate the fluid behavior in the test section. Given that working fluid conditions affect material performance, the potential effects of hydrogen on test materials are evaluated under operating conditions. The design studies performed show laminar flow behavior in the hydrogen and delivered required temperatures to the test section. This work provides the basis for design choices in the test system and correlation of hydrogen behavior in interior components to materials performance.

Cancelled
Quantification of the Resistance to Dislocation Glide in Pre-deformed and Ion-irradiated FeCrAl Alloys Using in Situ Micro-mechanical Testing: Jian Wang1; Dongyue Xie1; Tianyi Sun2; Xinghang Zhang2; Lin Shao3; 1University of Nebraska-Lincoln; 2Purdue University; 3Texas A&M University
    FeCrAl alloys become a competitive candidate for fuel cladding materials because of extraordinary oxidation resistance, excellent corrosion resistance at high-temperature and low parabolic oxidation rate. There is growing interest in FeCrAl alloys for nuclear applications. Correspondingly, the mechanical properties and behaviors of FeCrAl alloys, especially in irradiated state, must be thoroughly investigated. We prepared well-annealed, pre-deformed, and ion-irradiated FeCrAl samples and conducted in situ tension and compression testing in a SEM to evaluate the resistance to dislocation glide at different deformation temperatures. These results provide fundamentals for understanding mechanical behaviors of FeCrAl alloys at macro-scale.

Atomistic Calculations on the Effective Bias of Cavities in BCC Fe: Yuhao Wang1; Fei Gao1; Brian Wirth2; 1University of Michigan - Ann Arbor; 2University of Tennessee, Knoxville
    Cavity swelling is an important topic on F-M alloys and recent research reported that the classic thermal criterion of cavity nucleation lost its explanatory power outside the intermediate temperature regimes. Therefore, the bias was introduced for describing the reaction volume of different types of defects with cavities and the results will provide important inputs for cluster dynamics simulation. Molecular statics calculations were performed to determine the interaction radius and effective bias of single SIA/vacancy, di-SIA/vacancy and 7-SIA/vacancy clusters to voids in BCC Fe. Molecular dynamics simulations were conducted to investigate the rotation and migration behavior of SIA clusters with different sizes when interacting with a void. A specific homogenization method was established to describe the capture volume and mimic the one-dimensional diffusion behavior for large SIA clusters. The effective bias of single defects to He bubbles was also investigated with different bubble pressures and bubble sizes.

ACTINIS: Shielded SIMS for Analysis of Highly Radioactive Samples: Paula Peres1; Matt Pietrucha2; Seoyoun Choi1; Adrien Vuillaume1; Ludovic Renaud1; Nicolas Touzalin1; 1CAMECA; 2CAMECA Instruments Inc.
     Dynamic SIMS (Secondary Ion Mass Spectrometry) proves extremely useful for a wide range of nuclear science applications. ACTINIS is a SIMS instrument designed to perform high precision elemental and isotopic analyses of highly radioactive samples in a safe environment. ACTINIS offers depth profiling with excellent detection limits (ppb to ppm) and high depth resolution; elemental & isotopic information ranging from low mass (H) to high mass species (Pu and beyond); as well as unique sub-μm resolution 2D and 3D imaging capabilities. Studies performed with SIMS on irradiated nuclear fuel focus on three main axes: 1) the nuclear reactions occurring during in-core irradiation which are characterized with isotopic ratio measurements, 2) the physical and chemical behavior of fission products which is evidenced by isotopic mapping, 3) the characterization of fission gases which is carried out through depth profiling measurements.Different applications covered by ACTINIS for irradiated fuel analysis will be presented.

Atom Probe Tomography for Nuclear Materials: Robert Ulfig1; David Reinhard1; Keith Baxter1; Matthew Pietrucha; 1Cameca Instruments Inc.
     Atom Probe Tomography (3D imaging mass spectrometer) is the highest sensitivity analytical method identifying up to 80% of the atoms in a volume with sub-nanometer spatial resolution. The time-of-flight mass spectrometer has sufficient mass resolving power to identify individual isotopes of all masses from hydrogen to uranium and beyond with nominally equal sensitivity. Achieving this performance requires specialized specimen preparation, ultra-high vacuum, high-speed pulsing and timing electronics, as well as specialized data reduction techniques. Installations in France and the US have included modifications to facilitate the handling of radioactive materials with the mindset of time, distance, and, shielding.Over the 50 years since atom probe tomography was first demonstrated the technique has been developed to be fast and easy to use. This poster will summarize the technology and methods to achieve such performance with a focus on the contributions that APT has made for nuclear materials.

SKAPHIA: Presentation of the Latest Shielded Electron Probe Micro Analysis (EPMA): Anne-Sophie Robbes1; Matt Pietrucha2; Mathieu Lambert1; Adrien Vuillaume1; Michel Matton1; 1CAMECA; 2CAMECA Inc.
    Electron Probe Micro Analysis (EPMA) is used for material analysis, allowing quantitative mapping of nearly all chemical elements at concentration levels down to few 10s ppm with a spatial resolution of about 1 um. At nuclear facilities, EPMA is mainly being used for nuclear fuel characterization, irradiated materials behavior investigation, post Irradiation examination, and radioactive waste management. CAMECA has been developing dedicated EPMA instrumentation for radioactive samples for more than 40 years and launched SKAPHIA in 2017. We will present its global conception, the loading of hot sample, the safety capacities as well as the maintenance. Technical details to maintain the EPMA efficiency for detection limits of trace elements in the shielded environment will be reviewed. The instrument will be shown at our production facility and also integrated in various possible hotcell configurations. Finally, we’ll present different type of applications served by instruments in operation worldwide.

Developing Neural Network Model for Automated Analysis of Radiation-induced Grain Growth in UO2: Xinyuan Xu1; Zefeng Yu1; Arthur Motta1; Xing Wang1; 1Pennsylvania State University
    In the context of a research project designed to investigate the effect of in-situ Kr ion irradiation on grain growth in UO2, a large number of microscopy images have been generated at a range of temperature and doses. To aid in the processing of this large dataset and to reduce human bias, we developed a U-Net model to automatically recognize grains in dark field transmission electron microscopy (TEM) images and measure the grain sizes. U-Net is a convolutional neural network with a unique architecture that makes it efficient in image segmentation and particle analysis. The use of data augmentation through rotation, zooming, and shearing methods improved the model accuracy from 95% to 97%. The U-Net model successfully reproduced the grain growth kinetics from human experts with a much shorter processing time. The model can be further improved to analyze in-situ TEM videos and grain growth of other nanocrystalline materials.