At Argonne National Laboratory Research Articles

Status update of the ATLAS ECR ion sources at Argonne National Laboratory

The Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory (ANL) typically operates 24/7 with weekly ion beam changes and an annual 1 month maintenance period. Due to recent installations and upgrades at ATLAS, user demands for new beams and higher intensities have expanded an already diverse operational envelope of both electron cyclotron resonance ion sources (ECRIS), ECR2 and ECR3. A variety of material introduction techniques including sputter, oven, reduction and gas feed were used to meet the challenge of an intense run schedule. With two ECRIS available to feed the accelerator, beam development and preparation were able to occur concurrently with ATLAS programmatic activities. Highlights of operational experiences and improvements with ECR2 and ECR3 over the last 2 years are presented.

Accelerating communication with multi‐HCA aware collectives in MPI

SummaryTo accelerate the communication between nodes, supercomputers are now equipped with multiple network adapters per node, also referred to as HCAs (Host Channel Adapters), resulting in a “multi‐rail”/“multi‐HCA” network. For example, the ThetaGPU system at Argonne National Laboratory (ANL) has eight adapters per node; with this many networking resources available, utilizing all of them becomes non‐trivial. The Message Passing Interface (MPI) is a dominant model for high‐performance computing clusters. Not all MPI collectives utilize all resources, and this becomes more apparent with advances in bandwidth and adapter count in a given cluster. In this work, we provide a thorough performance analysis of existing multirail solutions and their implications on collectives and present the necessity for further enhancement. Specifically, we propose novel designs for hierarchical, multi‐HCA‐aware Allgather. The proposed designs fully utilize all the available network adapters within a node and provide high overlap between inter‐node and intra‐node communication. At the micro‐benchmark level, we see large inter‐node improvements up to 62% and 61% better than HPC‐X and MVAPICH2‐X for 1024 processes. Because Allgather is used in Ring‐Allreduce, our designs also improve its performance by 56% and 44% compared to HPC‐X and MVAPICH2‐X, respectively. At the application level, our enhanced Allgather shows and improvement in a matrix‐vector multiplication kernel when compared to HPC‐X and MVAPICH2‐X, and Allreduce performs up to 7.83% better in deep learning training against MVAPICH2‐X.

Cryogenic System Preliminary Design for a 0.5m-Long, Conduction-Cooled Nb3Sn Undulator Magnet Prototype

There are several NbTi superconducting undulator (SCU) magnets currently in operation at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The development on Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn-based superconducting undulator magnets at APS is underway due to the potential to further enhance the performance of the SCUs. Superconducting undulator magnets need to keep temperature gradients minimized in order to retain thermal and operating current margin. We have designed the thermal links for efficient heat conduction using 3D finite element analysis (FEA) simulation in COMSOL Multiphysics software, which was later used for the calculation of the temperature distribution across a 0.5 m long, conduction-cooled, Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn undulator magnet prototype that includes both conductive heat transfer and radiative heating components. We have modelled the evolution of the thermal properties of the magnet winding as well as other cold parts during cool-down from ambient temperature with the operation of a SHI RDK-415D cryocooler to examine the estimated time that is needed for the cooldown as well as the baseline temperature we could achieve. A key result was that a maximum coil <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta $</tex-math></inline-formula> T = 0.11 K along the designed thermal links and a temperature range of 3.42 K–3.53 K for the winding were predicted at steady state. A pair of G10 support rods for carrying the magnet as well as a pair of current leads made of metals were also designed and optimized for the testing system, targeting for an operation temperature of 4 K and a coil current of 950 A DC.

Automating Correlative Electron Microscopy for Heavy Duty Fuel Cell Development

The efficiency and durability of proton exchange membrane fuel cells has come to the forefront of research and development efforts as sustainable transportation applications shift from passenger to heavy duty vehicles. Complementary research expertise and advanced instrumentation are required to accelerate materials discovery and degradation mitigation of fuel cell components, with significant attention on catalysts, ionomers and membranes. The scanning transmission electron microscope (STEM) is among the key characterization techniques for accelerating materials and device development, providing key insights into atomic scale structure. Automating STEM data acquisition and analysis enables large data sets with improved statistical relevance and throughput will expand the impact of this method in the rapid materials and accelerated stress test development.We will show how the latest instrument developments in automation and high speed detectors enable new insights into catalyst structure and electrode layer degradation. This includes correlative, multimodal STEM techniques, such as aberration-corrected imaging, secondary electron detection, energy dispersive X-ray spectroscopy, cryogenic microscopy and 4D-STEM, to build a more comprehensive view of the effect of particle size and composition on surface strain and durability. These results will be correlated with information obtained from X-ray scattering techniques and fuel cell performance testing to understand the type and degree of degradation occurring during accelerated stress tests under development for heavy duty applications. The prospect of automated electron tomography coupled with identical location (IL)-STEM to provide detailed three-dimensional information on catalyst-support interactions will also be discussed.This material is based on work performed by the Million Mile Fuel Cell Truck (M2FCT) Consortium, technology managers Greg Kleen and Dimitrios Papageorgopoulus, which is supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office. Electron microscopy research was supported by the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory. The X-ray scattering experiments were performed at beamline 9-ID-C at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). Use of the APS, an Office of Science user facility operated by ANL, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AS02-06CH11357

Development, Verification, and Validation of an Advanced Systems Code KP-SAM for Kairos Power Fluoride Salt–Cooled High-Temperature Reactor (KP-FHR)

To meet the Kairos Power (KP) Fluoride Salt-Cooled High-Temperature Reactor (FHR) (KP-FHR) development and commercialization schedules, the System Analysis Module (SAM), which is an advanced systems code for Generation IV liquid-cooled reactors developed at Argonne National Laboratory (ANL), has been selected as the basis for the development of the KP-FHR systems code KP-SAM. This allows for an accelerated joint development effort between the KP and ANL teams. This paper presents a general overview of the KP-SAM development process, its current status, completed verification, and ongoing validation efforts. KP-SAM development follows the U.S. Nuclear Regulatory Commission Evaluation Model Development and Assessment Process framework. SAM is a high-order fully implicit transient systems code written in C++. The SAM software design, major physical models, and Jacobian Free Newton Krylov–based numerical methods are briefly discussed. KP-SAM has matured enough to be used for the unvalidated demonstration safety analysis for the low-power KP-FHR test reactor (Hermes) as part of Preliminary Safety Analysis Report work. By following the guidance of an internal KP-FHR thermal fluid Phenomena Identification and Ranking Table report, some of the most important separate-effects-test validations were completed for the first iteration. A scaled integral-effects test is under detailed design and will be built in 2022 to provide key data to validate KP-SAM for licensing safety analysis.

Production of C-14 and stable ion beams at the Argonne Tandem Linac Accelerator System with the ECR3 ion source

The Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory (ANL) paused production of carbon-14 ion beams with the removal of the Tandem Van de Graaff in 2013. Installation of ECR3, an Electron Cyclotron Resonance Ion Source, returned that production capability to ATLAS, with the first C-14 beam delivered in December 2020. Information is presented on C-14 beam current, gas consumption and N-14 filtering techniques using stripping foils at different sections of ATLAS. ECR3 also fulfilled the operational goal of adding flexibility to ATLAS stable beam production capabilities. Beneficial impacts to ATLAS operation, beam development and experimental programs are discussed.

Design of Experiments to Support VTR Core Design

To support the development of the U.S. Department of Energy (DOE) Versatile Test Reactor (VTR), a new set of experiments has been established at Argonne National Laboratory (ANL). Driven in part by the validation needs for code calculations and simulations of the reference VTR core design, three unique test facilities have been designed, or are in the process of being designed, to allow measurement of the phenomena and behavior prototypic to the full-scale VTR core. The Pressure drop Experimental Loop for Investigations of Core Assemblies in Nuclear reactors (PELICAN) facility, recently constructed and currently operational, is capable of producing full-scale flow rates for measurement of the pressure drop across a prototypic fuel assembly, including axial reflectors, fuel, and plenum components. The REDuced Scale Hydraulic Inlet Plenum (REDSHIP) experiment, beginning construction, will provide measurements of phenomena within the inlet plenum, including flow distributions through the core assembly ducts, pressure losses across the assembly receptacles, and localized velocity flow fields. A separate-effects-test experiment, called Parallel HEated ASsemblies for Advanced Nuclear Tests (PHEASANT), which is in the early stages of design, is being developed to examine the mixing of exiting core assembly jet streams within the upper plenum. As each of the test facilities becomes operational, they will begin generating timely, reliable, and qualified empirical data suitable for verification and validation of computational tools. In collaboration with other efforts across the DOE complex, the ANL experimental programs are well poised to provide continuous support for the advancement of the VTR design.

Characterization of in-situ ion irradiated Fe-21Cr-32Ni austenitic model alloy and alloy 800H at low doses

The microstructural evolution of ternary Fe-21Cr-32Ni (21Cr32Ni) model alloy and of alloy 800H was investigated with a series of in-situ ion irradiation experiments performed using the Intermediate Voltage Electron Microscope (IVEM)-Tandem Facility at Argonne National Laboratory (ANL). Samples were irradiated in-situ with 1 MeV Kr++ ions in the temperature range of 50K to 713K to doses up to 2 dpa. The size distribution of defect clusters, average defect cluster diameter, and defect cluster density were measured and compared. Results showed that the evolution of defects (i.e. the average defect cluster size and number density) in 21Cr32Ni model alloy and alloy 800H with dose were similar at irradiation temperatures up to 300K where they initially increased with dose up to 0.1 dpa after which no significant changes in defect size and density were observed with further irradiation. In addition, both alloys exhibited ordered defect structures along the <100> direction at relatively low temperatures, up to 300K, which remained stable throughout post-irradiation in-situ thermal annealing up to a temperature of 773K. During irradiation at 713K, small defect clusters were observed at low doses (<0.1 dpa) in both alloys. However, at this irradiation temperature, the clusters in 21Cr32Ni grew with a faster rate than those formed in alloy 800H, causing the microstructure in the former to be dominated by numerous large dislocation loops having both {111}- and {110}-type habit planes, and in the latter to be dominated by small defect clusters and small {111}-type dislocation loops. This may indicate that defect trapping by the solute atoms in alloy 800H at 713K can slow point defect migration to defect clusters and limit their growth.

Use of X-Ray Fluorescence Microscopy for Studies on Research Models of Hepatocellular Carcinoma.

Introduction: TheraSphere® microspheres containing yttrium 90Y are among many radioembolization agents used clinically to reduce liver tumor burden, and their effects on cancer volume reduction are well-established. At the same time, concerns about off target tissue injury often limit their use. Deeper investigation into tissue distribution and long-term impact of these microspheres could inform us about additional ways to use them in practice.Methods: Healthy rat liver and rabbit liver tumor samples from animals treated with TheraSpheres were sectioned and their elemental maps were generated by X-ray fluorescence microscopy (XFM) at the Advanced Photon Source (APS) synchrotron at Argonne National Laboratory (ANL).Results: Elemental imaging allowed us to identify the presence and distribution of TheraSpheres in animal tissues without the need for additional sample manipulation or staining. Ionizing radiation produced by 90Y radioactive contaminants present in these microspheres makes processing TheraSphere treated samples complex. Accumulation of microspheres in macrophages was observed.Conclusions: This is the first study that used XFM to evaluate the location of microspheres and radionuclides in animal liver and tumor samples introduced through radioembolization. XFM has shown promise in expanding our understanding of radioembolization and could be used for investigation of human patient samples in the future.

Balance-Of-Plant Computerized Operator Support System Implementation

A Computerized Operator Support System (COSS) is an operator assistive technology suite that aids operators in monitoring processes to detect off-normal conditions, diagnose plant faults, predict future plant states, recommend mitigation alternatives, and select appropriate mitigative actions. A COSS human-machine interface (HMI) was developed at Idaho National Laboratory (INL) in collaboration with an advanced prognostics engine called PRO-AID, developed at Argonne National Laboratory (ANL). The front-end HMI coupled with the back-end prognostics provide fault prediction to inform operators of plant faults before they occur. Historically, COSS has been focused within the control room, representing systems that are monitored and controlled solely from a centralized location. This project, however, is focused on applying the principles of previous COSS efforts to a system outside the control room, namely the boric acid concentrator and liquid radwaste (BAC/LRW) system. This effort demonstrates the applicability and usability of a COSS system in a balance-of-plant environment, and offers next steps in the development of operator support and advanced overview interfaces in existing nuclear power-generating stations, and the future advanced reactor systems.

Fracture simulation of SFR metallic fuel pin using finite element damage analysis method

This paper suggests a fracture simulation method for SFR metallic fuel pin under accident condition. Two major failure mechanisms - creep damage and eutectic penetration - are implemented in the suggested method. To simulate damaged element, stress-reduction concept to reduce stiffness of the damaged element is applied. Using the proposed method, the failure size of cladding can be predicted in addition to the failure time and failure site. To verify the suggested method, Whole-pin furnace (WPF) test and TREAT-M test conducted at Argonne National Laboratory (ANL) are simulated. In all cases, predicted results and experimental results are overall in good agreement. Based on the simulation result, the effect of eutectic-penetration depth representing failure behavior on failure size is studied.

Fabrication and Testing of 10-Pole Short-Period Nb3Sn Superconducting Undulator Magnets

NbTi superconducting undulators (SCUs) are currently reliably operating at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). These devices have significantly enhanced x-ray flux and brightness at the high energy spectrum. As NbTi SCU technology is close to its full potential, further performance enhancement requires using different superconducting materials. Nb3Sn is a promising candidate to achieve that goal. Recently the APS has started developing a Nb3Sn superconducting undulator compatible with the APS storage ring. The completed device is planned to be installed in the APS storage ring. To develop the Nb3Sn SCU technology, a series of short SCU models has been previously fabricated and successfully tested. In this study, the design has been further optimized to address previously unresolved problems. Several 10-pole, 4.5-period models were fabricated and tested. All of the fabricated models have reached the maximum operating current; however, one of the model, MM4, has failed right after reaching the maximum design current. The details of quench and training performances are presented.

Benchmark Simulation of the Natural Convection Shutdown Heat Removal Test Facility Using SAM

Natural convection systems are a promising method to passively remove heat from reactor cavities during loss of forced flow accident scenarios. At Argonne National Laboratory (ANL), a highly instrumented Natural Convection Shutdown Heat Removal Test Facility (NSTF) was used to demonstrate the effectiveness of air-cooled natural convection systems. In previous work, RELAP5-3D simulations were performed on this facility with favorable comparisons to experiment for mass flow rate, pressure drop, air temperature increase, and air velocity. Both experimental and simulation efforts with this facility present a useful opportunity to perform a benchmark study with the System Analysis Module (SAM). SAM is an advanced thermal-hydraulic system code currently in development at ANL for advanced non–light water reactor safety analysis.

First off-line tests and performance of the Notre Dame multi-reflection time-of-flight mass spectrometer

A multi-reflection time-of-flight mass spectrometer (MR-TOF) will be a critical component for quickly removing radioactive contaminants produced at the future “N = 126 factory” addition to ATLAS at Argonne National Laboratory (ANL). This unique thermalized ion beam facility will employ multi-nucleon transfer reactions to produce very neutron-rich isotopes relevant to the astrophysical r-process. Ion beams produced at this facility will include isobaric contaminants, while precision measurements of such rare isotopes typically require highly purified samples. Hence, to tackle this issue an MR-TOF has been built and commissioned at the University of Notre Dame in an off-line test setup comprising a thermionic source and a Bradbury-Nielsen gate (BNG) to create the ions bunches to be purified. Resolving power above 30,000, with a corresponding efficiency of 35%, has been achieved. Most of the ion beam losses could be the result of the large radial divergence of ion bunches produced by the BNG, hence greater efficiency and resolving power are expected once the MR-TOF is connected to an radiofrequency quadrupole (RFQ) cooler and buncher at ANL.

Reaction: Freezing Electrochemical Interfaces for Robustness in Electron Microscopy

Dr. Yifei Yuan obtained is PhD from Michigan Technological University in 2016. After 2 years of postdoctoral research at Argonne National Laboratory (ANL) and the University of Illinois at Chicago (UIC), he is now a research assistant professor working jointly at UIC and ANL. Dr. Jun Lu is a chemist at Argonne National Laboratory. His research interests focus on electrochemical energy storage and conversion technology with a main focus on technology beyond Li-ion batteries. He received his BS degree from the University of Science and Technology of China in 2000 and his PhD from the University of Utah in 2009.

Microstructural evolution of the 21Cr32Ni model alloy under irradiation

The microstructural evolution of the 21Cr32Ni model alloy under ion irradiation is investigated. A set of bulk materials were irradiated at the Michigan Ion Beam Laboratory using single beam (5 MeV Fe++) to 1, 10 and 20 dpa at 440 °C and dual beam (5 MeV Fe++ plus energy degraded 1.95 MeV He++ ions) to 16.6 dpa at 446 °C. The average diameter and number density of the faulted loops and cavities formed under irradiation were characterized using Transmission Electron Microscopy (TEM). The behavior of faulted loop in the model alloy was also investigated in-situ using the Intermediate Voltage Electron Microscope (IVEM) at Argonne National Laboratory (ANL). Results show that the average faulted loop diameter decreases, but the faulted loop number density increases with increasing dose. In-situ experiments showed that the faulted loops become unfaulted during ion irradiation by interacting with network dislocations. Although the average faulted loop diameter after 16.6 dpa dual beam irradiation at 446 °C was found to be similar to those seen in samples irradiated with single beams to 10 and 20 dpa, the faulted loop number density was significantly higher in the dual beam irradiated sample. Moreover, the dual beam irradiated model alloy exhibits a significantly higher density of smaller cavities. It is also found that the size and density of the faulted loops and voids calculated for the dual beam irradiation of 21Cr32Ni model alloy at 446 °C are in better agreement with those measured in a sample neutron irradiated at 375 °C. Further discussion is presented in this study.

A second-generation superconducting undulator cryostat for the APS

A second-generation cryocooler-based cryostat has been designed and built to support a new helically wound superconducting undulator (SCU) magnet for the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). The design represents an evolution of existing SCU cryostats currently in operation in the APS storage ring. Value engineering and lessons learned have resulted in a smaller, cheaper, and simpler cryostat design compatible with existing planar magnets as well as the new helically wound device. We describe heat load and quench response results, design and operational details, and the “build-to-spec” procurement strategy.

Towards laser spectroscopy of the proton-halo candidate boron-8

We propose to determine the nuclear charge radius of 8B by high-resolution laser spectroscopy. 8B (t 1/2 = 770 ms) is perhaps the best candidate of a nucleus exhibiting an extended proton wave-function or “one-proton-halo” in a more descriptive picture. Laser spectroscopic measurements of the isotope shift will be used to probe the change in nuclear charge radius along the three boron isotopes 8B, 10B and 11B. The change in nuclear charge radius directly correlates with the extent of the proton wave function. In-flight production and preparation of sufficient yields of 8B ions at low energies is provided by the Argonne Tandem Linac Accelerator System (ATLAS) at Argonne National Laboratory (ANL) in Chicago, IL, USA. Subsequently, the ions will be guided through a charge exchange cell for neutralization and the fluorescence signal of the atoms which interact with the resonant laser light will be detected. The charge radius can then be extracted from the measured isotope shift by employing highly accurate atomic theory calculations of this five-electron system which are carried out presently.

Mimicking Natural Photosynthsis: Ultrafast Charge Transfer in PpcA Ru(bpy)3 Complexes

Converting light energy into its electrochemical equivalent requires precise control and fine tuning of relevant kinetic and thermodynamic parameters, including primary charge separation. To this end, we developed a series of 22 cysteine mutants of PpcA, a 3-heme cytochrome from Geobacter sulfurreducens as a model system to study short distance photo-induced electron transfer. These proteins were successfully expressed in E.coli and isolated for covalent labeling with Ru(bpy)2(bpy-Br). Protein purity and successful posttranslational modifications were confirmed with HPLC-MS. Time-resolved nanosecond and ultrafast transient absorbance characterization was performed at Argonne National Laboratory (ANL) and identified 6 constructs with apparent photo-induced charge transfer time constants of 20 ps or faster, including 2 constructs with 1-2 ps time constants. The latter is a significant result as up to this point only natural photosynthetic systems demonstrated such a fast initial charge separation, while all artificial covalent constructs exhibited charge transfer rates 3 or more orders of magnitude slower. To understand molecular principles responsible for such a dramatic acceleration of electron transfer rates, we conducted small- and wide angle X-ray scattering data collection at the Advanced Photon Source at ANL. Further, we are currently attempting to obtain X-ray crystallographic and NMR structures of the ultrafast constructs. Finally, we performed triplicate 250-300 ns all-atom molecular dynamics simulations of all 6 ultrafast constructs. Based on the obtained results we conclude that that photo-induced ultrafast charge transfer requires van der Waals contact between heme vinyl groups and photosensitizers while contacts with propionates or short covalent donor-acceptor distances play a much less significant role.

The digital radiography of archaeological pottery: Program and protocols for the analysis of production

Archaeologists collaborating with material scientists at Argonne National Laboratory (ANL) as part of the Making of Ancient Eurasia (MAE) Project have developed formal methodological standards for the assemblage-based digital radiographic (DR) analysis of archaeological pottery. While analog radiography of pottery (X-radiography, Xeroradiography, etc.) has functioned as a common disciplinary tool for some time, inaccessibility, obsolescence, and significantly enhanced functionality have made DR instrumentation increasingly attractive and vital. This article presents the theoretical underpinnings, technique development, and resultant protocols that allow digital radiography to analyze very large assemblages and provide quantitative data sets that act as true counterparts to geochemical and mineralogical ones. As a technique of structural pottery evaluation, DR is particularly suited to the analysis of ceramic paste preparation and vessel formation, providing lines of evidence that can flesh out neglected portions of the chaîne opératoire, augment existing geochemical or typological classifications, and help more deeply characterize various potting traditions. Such datasets are most useful to scholars interested in harnessing the ability of the pottery “life cycle” to shed light on economic life, learning frameworks, and human social differences and group identities. The technical capacities and analytical potential of DR are demonstrated through several test analyses of ancient Chinese pottery, to be followed by more extensive case studies in draft. Prospects for closely related, three-dimensional X-ray computed tomographic approaches are also discussed.