Characterization of Nuclear Materials and Fuels with Advanced X-ray and Neutron Techniques: Neutron Diffraction and Imaging
Sponsored by: TMS Structural Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Nuclear Materials Committee
Program Organizers: Xuan Zhang, Argonne National Laboratory; Jonathan Almer, Argonne National Laboratory; Maria Okuniewski, Purdue University; Joshua Kane, Idaho National Laboratory; Donald Brown, Los Alamos National Laboratory; J. Kennedy, Idaho National Laboratory; Arthur Motta, Pennsylvania State University
Tuesday 8:30 AM
March 16, 2021
Room: RM 51
Location: TMS2021 Virtual
Session Chair: J. Rory Kennedy, Idaho National Laboratory; Donald Brown, Los Alamos National Laboratory
8:30 AM Invited
Advanced Characterization of Nuclear Fuel Using Neutron Imaging: Yuxuan Zhang1; Hassina Bilheux1; Kristian Myhre1; Jean Bilheux1; Jiao Lin2; Jared Johnson1; Andrew Miskowiec1; Rodney Hunt1; Louis Santodonato3; Jamie Molaison1; Paris Cornwell1; Erik Stringfellow1; 1Oak Ridge National Laboratory; 2Satelytics; 3Advanced Research Systems, Inc.
Nuclear fuel material is of high interest due to the increasing demand for clean energy. But many challenges are still presented in characterizing the fuel to guide the synthesis process. Conventional characterization techniques (i.e. scanning electron microscopy, optical microscopy, etc.) were widely used in the past, but they are often destructive and time-consuming in sample preparation. Moreover, extracting meaningful bulk information and post-irradiation information can be challenging. In this work, attenuation-based neutron computed tomography was performed at the High Flux Isotope Reactor to evaluate the presence of carbon agglomerates in TRISO fuel kernel three-dimensionally. Additionally, resonance computed tomography was developed at the Spallation Neutron Source to spatially resolve uranium and gadolinium content in produced fuel kernels. In this presentation, the basics of both the attenuation-based and resonance-based computed tomography and their applications in TRISO fuel characterization will be presented.
8:55 AM Invited
Neutron Imaging at LANSCE: Characterizing Nuclear Materials for Next Generation Reactor Designs.: Alexander Long1; Sven Vogel1; 1Los Alamos National Laboratory
Neutrons are an ideal probe for characterizing potential nuclear fuel and moderator materials for next generation nuclear reactors as the nature through which they interact with matter create complex attenuation functions that result in unique contrast mechanisms and material penetrabilities.Furthermore, given the variation of nuclear structure across all isotopes, fluctuations in neutron transmission spectra based on neutron-resonance absorptions can create isotope specific contrast mechanisms through which individual isotopes can be observed and identified.This technique, known as Energy Resolved Neutron Imaging (ERNI), is a powerful tool through which specific isotopes can be non-destructively mapped out in both 2D radiographs and 3D CT reconstructions.In this talk, I will discuss recent work at the Los Alamos Neutron Science Center (LANSCE) to develop advanced neutron radiography and ERNI capabilities on Flight Path 5 (FP5) specifically for characterizing nuclear fuels and moderator materials.
9:20 AM
Characterization of Irradiated Nuclear Fuels with Pulsed Neutrons: Sven Vogel1; Kenneth McClellan1; Luca Capriotti2; Jason Harp3; Alexander Long1; Danielle Schaper1; Eric Larson1; D. Travis Carver1; Jay Lin4; Peter Hosemann4; Thilo Balke5; 1Los Alamos National Laboratory; 2Idaho National Laboratory; 3Oak Ridge National Laboratory; 4UC Berkeley; 5LANL/Purdue University
Understanding irradiation effects in nuclear fuels is paramount to advancing nuclear power generation, though bulk characterizations of irradiated fuels are difficult due to extreme radiation environments (>100 R/hr) resulting in a lack of non-destructive tools capable of interrogating irradiated materials. The ability of neutrons to penetrate containers as well as fuel material offer unique advanced post-irradiation examination capabilities to close this gap and potentially guide further destructive examination of smaller volumes of interest. Short pulsed neutron sources, such as LANSCE, enable characterization modalities ranging from time-of-flight diffraction to energy-resolved neutron imaging to neutron absorption resonance spectroscopy. We will present preliminary results on a 6 mm diameter, ~2mm thick slice of ATR-irradiated U-10Zr-1Pd characterized with these modalities (NSUF supported) as well as our pathway to characterize irradiated minor actinide bearing MOX pellets of the AFC-2C/2D irradiation campaign, including a cask designed to enable characterization of these samples in beamlines at LANSCE.
9:40 AM
Characterization of the Crystal Structure Evolution of U-Zr Alloys Utilizing Time-of-Flight Neutron Diffraction with In-situ-heating: Walter Williams1; Sven Vogel2; Jianzhong Zhang2; Maria Okuniewski3; 1Idaho National Laboratory; 2Los Alamos National Laboratory; 3Purdue University
Metallic U-Zr alloys are typically operated in nuclear reactors over a 400-750°C temperature range and experience multiple irradiation, chemical, and thermal-induced phenomena that influence both chemistry and microstructure. Decoupling these dependencies is critical to the understanding of material behavior, modelling and simulation, and in-pile safety margins. Time-of-flight neutron diffraction was chosen as the experimental technique for its versatility in sample characterization. This versatility allows for the simultaneous identification of crystallographic phases and measurement of phase specific texture and crystallographic parameters such as lattice parameters, thermal expansion, and site occupation in equilibrium and non-equilibrium systems. Unirradiated samples of U-(6,10,20, and 30)wt.%Zr were analyzed on the High-Pressure-Preferred Orientation beamline at room temperature, during a two-hour 900°C anneal, and during a 1°C/min cooling rate. Data acquisition included extended high-resolution scans and rapid scans capable of capturing phase evolution and transformation kinetics. Data acquisition encompassed over 20,000 neutron diffraction patterns.
10:00 AM
Microstructure and Crystal Structure Studies in the U-Zr System: Sven Vogel1; Yi Xie2; Luca Capriotti3; Michael Benson3; Jason Harp4; 1Los Alamos National Laboratory; 2Purdue University; 3Idaho National Laboratory; 4Oak Ridge National Laboratory
U-Zr–based nuclear fuel is a leading choice for sodium-cooled fast reactors, as it has advantages of high fissile density, high thermal conductivity, ease of fabrication, ability to incorporate minor actinides, and good compatibility with coolants. To investigate the microstructure evolution of U-Zr fuels, samples of U-2Zr, U-10Zr, U-35Zr, and U-50Zr were studied in situ by neutron time-of-flight diffraction on the HIPPO instrument at LANSCE. All samples underwent the same temperature profile of heating from room temperature to 600°C, then 650°C followed by 5°C increments to 700°C before an anneal at 800°C. During cooling, the same profile was applied except for a hold of several hours at 600°C prior to cooling back to room temperature. This temperature profile allows the kinetics of phase transformations between delta/omega, beta, and gamma phases occurring during heating and cooling to be studied. The results of this study will be presented.
10:20 AM
Non-destructive Characterization of Nuclear Materials using Neutron Imaging Techniques: Hassina Bilheux1; Yuxuan Zhang1; Jean Bilheux1; Erik Stringfellow1; Kristian Myhre1; Brianne Beers1; Brent Heuser1; Tommy Thomasson1; Amy Jones1; Richard Ibberson1; 1Oak Ridge National Laboratory
Non-destructive characterization of nuclear materials such as cladding materials or nuclear fuels are often difficult to perform due to the scarcity of samples prepared under conditions similar to commercial reactor environments, but also because handling some of these materials at a research facility (where neutrons sources are often located) requires special radiation precautions. In addition, penetration through high-Z materials in nuclear fuels causes a major challenge for most probing techniques. Neutrons are sensitive to light elements such as hydrogen and are not easily attenuated by heavy elements. Hence, neutron scattering techniques offer a unique insight into materials that are critical to nuclear industry. At research reactors, neutron computed tomography is a 3D technique capable of identifying defects such as cracks and porosity, but also the presence of hydrogen in cladding material for example. Spallation neutron sources offer unique neutron-wavelength dependent characterization capabilities (i.e. the material’s crystalline structure and isotopic content). -- Acknowledgements: This research used resources at the Spallation Neutron Source and the High Flux Isotope Reactor, U.S. Department of Energy (DOE) Office of Science User Facilities operated by the Oak Ridge National Laboratory. -- Notice of Copyright:This abstract has been authored by UT-Battelle, LLC, under Contract No. DE AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.
10:40 AM
Neutron Radiography Capabilities at LANSCE: Completing LANSCE's Cold/Thermal/Epithermal Imaging Suite With Fast-neutron Radiography: Danielle Schaper1; Jeremy Bundgaard2; Carl Carlson2; Patrick Feng3; Donald Gautier1; Alexander Long1; Darcy Newmark1; Sven Vogel1; 1Los Alamos National Laboratory; 2Nevada National Security Site; 3Sandia National Laboratory
Neutrons possess two crucial characteristics which allow them to interact uniquely with materials: their uncharged nature is why neutrons often have large penetration depths, and their highly-isotope dependent nuclear interactions can be used to identify and quantify isotopic compositions in complex, mixed-material objects. These properties allow neutron radiography to offer a powerful, non-destructive probe which is often complementary to similar measurements done using x-rays and charged particle radiography. In this talk, we will present a broad overview picture of the current neutron radiography capabilities at the Los Alamos Neutron Science Center (LANSCE), ranging from Energy Resolved Neutron Imaging (ERNI) techniques to fast-neutron radiography on Flight Path 60-R at the WNR. Specifically, we will discuss how ERNI measurements are used to characterize nuclear materials, and how fast-neutrons at FP60R can be used to test and characterize newly-developed scintillator materials.
11:00 AM
Transmission Spectrum Estimation and Material Decomposition with Energy Resolved Neutron Imaging: Thilo Balke1; Alexander Long1; Sven Vogel1; Brendt Wohlberg1; Charles Bouman1; 1Los Alamos National Laboratory
Time-of-flight (TOF) neutron detectors with a pulsed, white neutron source enable imaging of energy resolved radiographs. Given that isotopes have distinctive neutroncross sections, especially in the resolved resonance region, material information can be further decomposed based on its isotopic composition. Acquiring different angles of the sample thus allows for material decomposed computed tomography (CT) imaging. For the purpose of decomposition of a transmission spectrum, high fidelity analysis software like SAMMY (ORNL) can be used. However, this software is not optimized for processing large amounts of data as it is necessary for a CT application (billions of spectra per CT scan). We present a series of performance optimized algorithms to process and material decompose large amounts of TOF image data. We are using a novel, parallelized background estimation technique, and a material decomposition based on basis pursuit denoising with a precomputed dictionary of broadened neutron cross-section data.