Learning from Each Other: Cross-Cutting Diagnostic Development Activities Between Magnetic and Inertial Confinement Fusion
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Catalytic Combustion for Ultra-Low NOx Hydrogen Turbines
Precision Combustion, Inc., (PCI) in close collaboration with Solar Turbines, Incorporated, has developed and demonstrated a combustion system for hydrogen fueled turbines that reduces NOx to low single digit level while maintaining or improving current levels of efficiency and eliminating emissions of carbon dioxide. Full scale Rich Catalytic Hydrogen (RCH1) injector was developed and successfully tested at Solar Turbines, Incorporated high pressure test facility demonstrating low single digit NOx emissions for hydrogen fuel in the range of 2200F-2750F. This development work was based on initial subscale development for faster turnaround and reduced cost. Subscale testing provided promising results for 42% and 52% H2 with NOx emissions of less than 2 ppm with improved flame stability. In addition, catalytic reactor element testing for substrate oxidation, thermal cyclic injector testing to simulate start-stop operation in a gas turbine environment, and steady state 15 atm. operation testing were performed successfully. The testing demonstrated stable and robust catalytic element component life for gas turbine conditions. The benefit of the catalytic hydrogen combustor technology includes capability of delivering near-zero NOx without costly post-combustion controls and without requirement for added sulfur control. In addition, reduced acoustics increase gas turbine component life. These advantages advances Department of Energy (DOE’s) objectives for achievement of low single digit NOx emissions, improvement in efficiency vs. postcombustion controls, fuel flexibility, a significant net reduction in Integrated Gasification Combined Cycle (IGCC) system net capital and operating costs, and a route to commercialization across the power generation field from micro turbines to industrial and utility turbines.
42 ENGINEERING↗
Development of Plasticity Model Using Non-Associated Flow Rule for HCP Materials Including Zirconium for Nuclear Applications
In this report (prepared in collaboration with Prof. Jeong Whan Yoon, Deakin University, Melbourne, Australia) a research effort was made to develop a non associated flow rule for zirconium. Since Zr is a hexagonally close packed (hcp) material, it is impossible to describe its plastic response under arbitrary loading conditions with any associated flow rule (e.g. von Mises). As a result of strong tension compression asymmetry of the yield stress and anisotropy, zirconium displays plastic behavior that requires a more sophisticated approach. Consequently, a new general asymmetric yield function has been developed which accommodates mathematically the four directional anisotropies along 0 degrees, 45 degrees, 90 degrees, and biaxial, under tension and compression. Stress anisotropy has been completely decoupled from the r value by using non associated flow plasticity, where yield function and plastic potential have been treated separately to take care of stress and r value directionalities, respectively. This theoretical development has been verified using Zr alloys at room temperature as an example as these materials have very strong SD (Strength Differential) effect. The proposed yield function reasonably well models the evolution of yield surfaces for a zirconium clock rolled plate during in plane and through thickness compression. It has been found that this function can predict both tension and compression asymmetry mathematically without any numerical tolerance and shows the significant improvement compared to any reported functions. Finally, in the end of the report, a program of further research is outlined aimed at constructing tensorial relationships for the temperature and fluence dependent creep surfaces for Zr, Zircaloy 2, and Zircaloy 4.
42 ENGINEERING↗
Proliferated Resilient Economical Half-Meter Aperture Space Telescopes (PREEMPT)
The PREEMPT LDRD was motivated by a major national need for better space-based imaging systems that are both high performing and affordable for the US Government. Current optical payloads for intelligence, surveillance and reconnaissance (ISR) and space domain awareness (SDA) missions can cost hundreds of millions of dollars and take years to develop, which makes it difficult to build the large constellations required for persistent, world-wide coverage. To address this, the team aimed to advance a different kind of large-aperture (>25 cm) telescope, called a monolithic telescope, in which key optical surfaces are built into a single piece of fused silica. This design greatly reduces payload and spacecraft complexity, the need for precision focus actuators, improves mechanical and thermal robustness, and lowers cost when compared with traditional Cassegrain telescopes that rely on many precisely aligned components. The project focused on five primary thrusts. The first thrust was to advance the concept of a V10, 25 cm, monolithic telescope forward from optical design to flight-ready stage. This was accomplished in partnership with Optimax, who delivered the first test unit in the early stages of the LDRD. The team developed several technologies necessary for this optic to be integrated into a flight demonstration. These include carbon fiber housings, highly detailed structural and thermal models and stress-reducing elastic averaging Hirth groove designs. These technologies resulted in a successful maturation of the optic, which is now slated to fly in late 2026/early 2027 for a demonstration mission. The second thrust was to advance the manufacturability of these optics. In collaboration with NIF’s optical manufacturing shop, we reduced polishing time from 480 hours to 65 hours through the implementation of optimized processes and new tools. The NIF team utilized a conceptual V8 (18 cm) optic to demonstrate this optimization, though it can be applied to the rest of the monolithic optic portfolio. Third, the team developed the first conceptual V20 (50 cm) payload, which is slated to be the next generation of LLNL optical payload systems. A set of structural, dynamic and thermal simulations were performed to identify potential challenges in the future development of this payload. Early-stage simulations suggest the payload is feasible, though thermal management will be the key focus area to maintain optimal performance. Fourth, a non-linear model of Viton was developed, to further enhance the reliability of our structural and dynamic models for future payloads. Viton acts as the primary interface material between the optic and its housing. Lastly, the team focused on successfully displaying the feasibility of using additively manufactured metal composites for optical space payloads. The team successfully demonstrated layer by layer deposition of Al-SiC composites, which have highly tunable structural and coefficient of thermal expansion (CTE) properties. These are crucial for optical payloads because CTE mismatch is one of the causes for degraded optical performance for telescopes in orbit. Overall, the work showed that monolithic telescopes could become a practical, lower-cost path to high-resolution space imaging for both national security and scientific missions.
42 ENGINEERING↗
International Collaboration Framework for the Calculation of Performance Loss Rates: Data Quality, Benchmarks, and Trends
Within the IEA PVPS Task 13, a group of experts representing several leading R&D centres, universities and industry companies, is developing a framework for the calculation of Performance Loss Rates (PLR) on a large number of commercial and research PV power plants and related weather data coming from various climatic zones. Various methodologies are applied for the calculation of PLR which are benchmarked in terms of uncertainties and 'true' values. The aim of the international collaboration is to show how to calculate the PLR on high quality (high time resolution, reliable data, irradiance, yield, etc.) and on low quality data (low time resolution, only energy data available). Various algorithms and models, along with different time averaging and filtering criteria, can be applied for the calculation of PLR each of which can have an impact on the results. The approach considers three pathways to ensure broad collaboration and increase the statistical relevance of the study: i) use of shared methodologies on shared time series, ii) use of confidential methodologies on shared time series, iii) use of shared methodologies on confidential time series. The data is used for benchmarking activities and to define which methodologies clusters around a 'true value' of PLR. The combination of metrics (PR or power based) and methodologies are benchmarked in terms of deviation from the average value and in terms of standard deviation. The combination of temperature corrected PR with the use of Year on Year (YOY) or Seasonal Trend decomposition using Loess (STL) performs well for all systems; other methodologies seems to be more depending on the filtering applied. Another set of data is represented by the IEA PVPS Task 13 'PV performance database' which includes more than 120 PV plants from different climates. The applied methodologies were STL and the YoY approach. STL results in an averaged PLR over all systems of -0.78%/a while YoY yields -0.63%/a. STL is better suited if the time series data are of higher resolution and high-quality weather data are available. One important outcome of this study is the setting of a framework for the contribution to a clear and structured quality classification for PV time series data and a guideline for PLR calculations in dependency of the data categorization.
14 SOLAR ENERGY↗
WM26 Paper Multi-Robot Collaboration for Hazardous Environments
Hazardous nuclear and industrial facilities are rarely designed for robots. Work in these domains demand precise manipulation and robust mobility in cluttered, constrained spaces where off-the-shelf platforms struggle and “one-size-fits-all” machines become costly and complex. Idaho National Laboratory (INL) is developing an autonomous, multi-robot inspection system that coordinates task-specific platforms rather than relying on a single omni-tool robot. An electric truck serves as a power and compute hub for a custom manipulator co-developed with Florida International University (FIU), a commercial mini crawler, a pan–tilt–zoom camera, and a Nexxis Argus LiDAR mapping system. Working in concert, these robots generate spatial, radiation, and temperature maps of the pit environments at the Hanford Waste Tank Farms. These systems will capture visual records and environmental telemetry to allow for analysis post inspection. The system architecture uses Robot Operating System 2 (ROS 2) for publish/subscribe integration, NVIDIA Isaac Sim and Unity for simulation and visualization, and algorithms such as NVBlox to fuse data into unified 3D overlays. This robot-agnostic approach reduces operator burden by enabling autonomy across heterogeneous platforms and lets each robot be used where it is strongest. Having autonomous functions means operators don’t have to fully control multiple different components. The ease of use could allow for more widespread adoption of advanced robotics at waste management sites that see continued use. By coordinating simpler, purpose-built mechanisms, the approach lowers design and manufacturing complexity, reduces capital risk in contaminated settings, and improves controllability for complex inspection and manipulation tasks. We present the architecture, early results, and lessons learned from building and deploying this coordinated multi-robot system, with the goal of accelerating safe, cost-effective adoption of advanced robotics at waste-management sites.
42 - ENGINEERING↗
Seismic Analysis of Spatio-Temporal Fracture Generation During EGS Resource Development
This DOE GTO funded project was a collaborative effort between Array Information Technology and the University of California at Berkeley. The project goal is to improve technology to assess in-situ stress magnitude and orientation, kinematic fracture parameters, rupture size, rupture orientation as well as temporal changes and volumetric distribution of the injected fluid during Enhanced Geothermal System (EGS) resource development. The project leveraged high-frequency seismic data recorded by the LBNL 34-station permanent geophone network and seismic broadband data recorded by a temporary 33-station seismometer network that operated in The Geysers during the injection phase of the DOE GTO funded EGS demonstration project at the well Prati-32. The operation of the broadband network with high station density and good azimuthal coverage to monitor the injection phase produced an unprecedented dataset that is typically unavailable for EGS operations. The two datasets offer the advantages of studying the parameters under investigation over a broader frequency band and the higher sensitivity of the broadband seismometers resulted in a richer dataset with a lower magnitude of completeness. Moment tensor (MT) inversion have been employed to develop a catalog of earthquake source solutions including moment tensor and finite source rupture area. This resulted in a 168-event waveform-based seismic moment tensor catalog for events 0.7≤Mw≤3.9 based on a semi-automated moment tensor analysis technique. The MT solutions were used for in-situ stress estimation during the EGS injection phases. We found an approximate 15-degree counterclockwise rotation of the least compressive stress sigma-3, and a rotation of the maximum compressive stress sigma-1 toward the vertical as the injected volume of water increased. We developed a rupture-area magnitude scaling relationship of The Geysers earthquakes obtained from finite-source inversion for fault slip that reveals a very high correlation to published results. Based on the rupture area-magnitude relationship we mapped Mw from the LBNL earthquake catalog to estimate the activated fracture area, its location and orientation within the injection volume of Prati-32. The double-difference Wadati (DDW) technique was applied to high-accuracy P- and S-wave differential travel times derived from waveform cross correlation to image fluid saturation in the subsurface based on Vp/Vs-ratio. The recently developed technique has been applied to estimate temporal changes of fluid distribution in fault zones and in volcanic regions but not yet in engineered geo-reservoirs. The improvement of the technology includes high-resolution waveform cross correlation applied to the high-quality datasets with lower magnitude of completeness resulting in a higher number of recorded events. The improvement allowed to estimate both, the spatial and temporal distribution of injected fluids and the state of the injected fluid during reservoir stimulation. Results of the DDW analysis revealed the development of an injection-derived steam plume during the early injection phase, particularly in the northern part of the Prati-32 study area.
15 GEOTHERMAL ENERGY↗
Formation and reconfiguration of tight multi-lane platoons
Advances in vehicular communication technologies are expected to facilitate cooperative driving in the future. Connected and Automated Vehicles (CAVs) are able to collaboratively plan and execute driving maneuvers by sharing their perceptual knowledge and future plans. In this paper, an architecture for autonomous navigation of tight multi-lane platoons traveling on public roads is presented. Using the proposed approach, CAVs are able to form single or multi-lane platoons of various geometrical configurations. They are able to reshape and adjust their configurations according to changes in the environment. The proposed architecture consists of two main components: an offline motion planner system and an online hierarchical control system. The motion planner uses an optimization-based approach for cooperative formation and reconfiguration in tight spaces. A constrained optimization scheme is used to plan smooth, dynamically feasible and collision-free trajectories for all the vehicles within the platoon. The paper addresses online computation limitations by employing a family of maneuvers precomputed offline and stored on a look-up table on the vehicles. The online hierarchical control system is composed of three levels: a traffic operation system (TOS), a decision-maker, and a path-follower. The TOS determines the desired platoon reconfiguration. The decision-maker checks the feasibility of the reconfiguration plan based on real-time information about the surrounding traffic. The reconfiguration maneuver is executed by a low-level path-following feedback controller in real-time. The effectiveness of the approach is demonstrated through simulations of three case studies: (1) formation reconfiguration (2) obstacle avoidance, and (3) benchmarking against behavior-based planning in which the desired formation is achieved using a sequence of motion primitives.
42 ENGINEERING↗
Nevada National Security Site Site-Directed Research and Development Report (FY 2018 Annual Report)
This report compiles multiple articles describing activities developed and performed under the Site-Directed Research and Development Program for the benefit the Nation during Fiscal Year 2018. Sustained investment and ongoing core innovation are the keys to successful research and development programs. These elements drive the Site-Directed Research and Development (SDRD) Program and provide solutions to some of the most challenging problems our nation and our allies face. Our Nevada enterprise, consisting of both our management and operating entity and our NNSA field office, is aggressively investing in SDRD and injecting innovation through strategic partnerships. Our partnerships with universities, industry, and our sister institutions within the National Nuclear Security Administration (NNSA) build upon our core capabilities and allow us to create innovative solutions to support our mission requirements. In 2018, we raised the investment level of SDRD for only the second time in the history of the program. Nearly at our congressionally authorized limit, SDRD has substantial resources to successfully address numerous issues. Investment is only one part of the equation; innovation is generated through collaborations that bring discovery and provide the “technical differentiation” and the return on investment we seek. This report demonstrates an enduring theme of how partnerships help us drive the best outcomes and provide the maximum impact possible, while using our resources efficiently.
36 MATERIALS SCIENCE↗
Interlaboratory comparison of secondary ion mass spectrometry analysis results from the 7th international technical nuclear forensics working group collaborative material exercise
A review and interlaboratory comparison of secondary ion mass spectrometry (SIMS) data obtained by laboratories participating in the International Technical Nuclear Forensics Working Group (ITWG) 7th Collaborative Material Exercise (CMX-7) has been conducted. The analyzed materials were two uranium compounds in powder form and two pieces of uranium metal. The instruments used in this comparison were a small-geometry (SG) SIMS, CAMECA IMS 7f from the Research Centre Rez, and a large-geometry (LG) SIMS, CAMECA IMS 1280 from Los Alamos National Laboratory. Despite the differences in instruments and analytical procedures, e.g., sample preparation, SIMS setups, and data post-processing, there was good agreement for the 234 U/ 238 U, 235 U/ 238 U, and 236 U/ 238 U ratios in the analyzed materials. The main difference was in the precision, which was, as expected, higher for the LG-SIMS. In addition, a comparison between the laboratories was also made for the image processing algorithms applied to raw data acquired in automated particle measurement (APM) mode. In conclusion, the result of this comparison has led to identification of best practices for setting up parameters of the APM software.
and nuclear chemistry↗
Evaluation of LPBF Steels for Nuclear Applications
This report provides an update on the prioritization of existing reactor materials for advanced manufacturing. This report is a Milestone 3 deliverable in FY2023, under work package CT-23AN130401 to support research and qualification activities supported by the Advanced Materials and Manufacturing Technologies (AMMT) program here at Argonne National Laboratory (ANL). The focus of FY23 for ANL included the determination of a decision criteria matrix for the prioritization of existing materials, the literature review of a select few Fe-based alloys, and working with vendors to obtain customized powders. The work package also includes fabricating test samples in a Renishaw AM400 Laser Powder Bed Fusion (LPBF) system and optimizing the process parameters. The major outcomes of this work package are: With collaborations from PNNL, ORNL, and INL, we were able to establish a decision criteria matrix containing a total of 6 categories and 31 different criteria. These will be used to downselect alloys for further evaluation; As part of that, 6 different Fe-based alloys were selected, 3 austenitic stainless steels (A709, D9, AFA) and 3 ferritic/martensitic steels (HT9, Grade 91, Grade 92). Customized powders were obtained from vendors in small quantities to fabricate initial prints to check printability of these specific alloys; A total of 72 single track experiments were performed on two alloy systems, 1 austenitic stainless steel (A709) and 1 ferritic/martensitic steel (Grade 91) in order to optimize the process parameters for the full 3d prints. The optimization led to the selection of 20 different processing conditions, 10 for each class of alloys; D9 and AFA alloys showed extensive cracking and porosity in the samples. This was due to less-than-ideal conditions present in the chamber during the deposition. A709 printed using the same process parameters showed almost fully dense samples with no noticeable porosity or any other defects. SEM and EBSD analysis revealed single phase FCC microstructure with cellular structure within the grains; HT9, Grade 91, Grade 92 alloys also showed no noticeable signs of cracking and ImageJ analysis showed porosity <0.5% in all conditions. While Grade 91 and Grade 92 showed single phase BCC microstructures, the presence of martensite laths was noted in HT9 alloy; Future work will include further characterization of these alloys to better understand the microstructural evolution during the 3d printing process.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Filament Extension Atomization for High Solids Loading in Energy Efficient Spray Drying Systems
We demonstrate that we could scale FEA to reach outputs needed by industrial production, while increasing solids loading of the sprayed product by at least 30% and maintaining equal or better spray powder. After testing a wide range of products, in collaboration with industry partners we decided on our primary spray products of dry whey and WPC-80, two common materials processed and sold by US manufacturers with different parameters. We sprayed these with FEA at solids loadings of 70% for dry whey and 45% for WPC-80 with a spray output with particle sizes similar to industrial particles sizes and reduced variation in particle size. We simultaneously scaled up FEA first with a multi-nip with 6 nips surrounding a central roller with parallel axis of rotation and eventually with a tapered design that solved problems we encountered with our initial design. We were able to achieve output from a single array from our first design of up to 4.7 liters per minute (L/min) and from an array of our second multi-nip of 8 L/min exceeding expectations. This demonstrates that FEA technology can indeed be scaled up to meet the needs of industrial production. More arrays can be added as necessary to meet a wide range of spray dryer designs. We also tested FEA to create dried powders from a small scale (10 L/hour of water removal) spray dryer. Though we were not able to produce large quantities of powder from FEA due to challenges in integration, the powder we produced was higher quality and produced from higher solids loading materials. From our technoeconomic analysis we for a typically sized spray dryer, we estimate a 27% cost reduction and 41% energy and carbon reduction for WPC-80 and a 39-57% cost reduction and 52-76% energy reduction for sweet dry whey (depending on the exact product).
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
2013 Caliban and Prospero experiments for the study of the behavior of radiation protection instrumentations in case of a criticality accident - 14346
Experiments using the CALIBAN and PROSPERO reactors were performed in 2013 in the framework of a collaboration between IRSN and CEA. The objective was to provide data about the possibility to use information given by radiation protection instrumentations (RPI) in the case of a criticality accident. In that purpose, the behavior of RPI was studied for various kinetics of the reactors which simulated different starts of a criticality accident. The article presents the safety issues associated with these experiments, i.e. the possible use of information given by the RPI for the emergency response of a criticality accident (detection of the accident, triage of the personnel, follow-up of the accident and reentry). Then, one paragraph is dedicated to the presentation of the tested material. In addition, the CALIBAN and PROSPERO reactors are briefly described, followed by the performed experiments. The RPI are neither designed nor dedicated to be used in case of a criticality accident. However, the preliminary conclusion of the experiments performed in 2013 is that the tested RPI have a correct behavior for slow kinetic experiments performed with the PROSPERO reactor, but might give less reliable and accurate information for pulse experiments performed with the CALIBAN reactor. In the last case, they can nevertheless provide information that can be helpful for the emergency response and the limitation of the consequences of the criticality accident. However, if the RPI are included in the emergency response of a criticality accident (detection, triage, follow-up, reentry), emergency procedures should be adapted. Other experiments might be performed in order to confirm results and to extend the number of tested materials, in particular portable survey meters or contamination area monitors. (authors)
42 ENGINEERING↗
Savannah River Site H-Canyon Collaborative Advanced Technology Demonstration (ATD) - 18313
In support of the Department of Energy's Environmental Management Office of Technology Development (DOE-EM TD) Robotics Technology thrust to pull innovative commercial off the shelf (COTS) and near ready technologies to the field to expedite remaining EM mission clean up and enhance worker safety, the required FY19 Savannah River Site (SRS) H-Canyon Air Exhaust (HCAEX) tunnel inspection task will be used to demonstrate and evaluate the benefit of pulling advanced technology solutions to EM facilities. Presently a biannual visual inspection of the SRS HCAEX tunnel is required to evaluate the structural integrity of the tunnel. While the ability to see inside the tunnel in recent years has been highly invaluable, it is desirable to have a better understanding of the tunnel environment to support a more thorough structural integrity analysis and for long term planning purposes. This higher order of understanding can be accomplished through state of the art COTS sensors and those currently in development and near ready. The ATD will identify and develop for deployment advanced technologies to be hosted on the FY19 inspection platform to acquire high value data desired by the stakeholder. This presentation will include an overview of the ATD mission, background on the tunnel and harsh remote environment in which the inspection robot will work and the high priority inspection needs identified by the H-Canyon facility stakeholders. Discussion will include previous and planned robotic platform modifications to facilitate work in the tunnel and a discussion on the advanced technologies identified to be implemented for the inspection. The ATD will be completed over approximately a 2-year period and has already begun in the form of planning, identification of stakeholder needs, specification of a robust platform and identification of the high priority sensor needs to be pursued. This presentation will be a status of the ATD at approximately the 7-month mark. (authors)
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Exchange anisotropy, engineered coercivity and spintronics in atomically engineered L1 0 heterostructures
We identified and investigated some of the scientific and technically most challenging issues in thin film magnetism focusing on epitaxially grown layers of specific L1 0 ordered, intermetallic, heterostructures with well-controlled crystallography and interface structures. Specifically, we addressed antiferromagnetic/ferromagnetic heterostructures, exhibiting exchange bias (EB) in both in-plane (MnPd/Fe) and perpendicular (IrMn/(Co/Pt) n ) geometries, and ferromagnetic/ferrimagnetic (Co/Y 3 Fe 5 O 12 ) bilayers with strong interlayer exchange coupling and exhibiting spin reorientation transitions. In the former case, the work included experimental and theoretical studies to gain more fundamental insight into the origin and magnitude of EB, as well as to address important aspects of EB such as the asymmetry in the magnetic reversal mechanism, the role of interfacial structure, including compensated or uncompensated spins, AF domains, competing anisotropies and the angular dependence of the magnetization reversal process. Exchange bias is central to many magnetic technologies and driven by the fast development of nanotechnology, there is much interest in understanding the phenomenon of exchange bias on the nanoscale. By patterning, as the FM domain size reaches a lateral scale comparable to the AF domain size (~100nm), each nano-element can be treated as a separate and isolated exchange bias system that behaves independently. Therefore, the non-averaged, intrinsic, exchange bias, in all its complexity, can be studied. Such size and dimensionality effects, particularly in structures with lateral dimension of the order of their domain sizes, were studied by developing and implementing a novel Nano-imprint as well as convention optical lithography/patterning. However, one limitation of the NIL method is that after imprinting the material-deposition or -evaporation has to be done at around room temperature in order to keep the resists structure undisturbed. As a result, the method is unsuitable for epitaxial growth, since the latter often involves growth at elevated temperatures higher than the glass transition temperature of the resist. Therefore, a mask transfer NIL process was developed to grow epitaxial nanostructure arrays at elevated temperatures where organic resists are rendered unstable. In the case of the metal/oxide heterostructures, the domain structure of the metal is carefully modulated by that of the underlying oxide, opening the possibility of carrying out novel experiments to study spin-dependent domain-wall scattering and quantify domain wall resistance in mesoscopic geometries. Utilizing state-of-the-art characterization methods, using synchrotron radiation and electron holography, we addressed the critical role of all aspects of the microstructure, at relevant length scales, in determining these specific magnetic properties. Two significant highlights of this project were the use of photoemission electron microscopy (PEEM) work to elucidate their asymmetric magnetization reversal mechanism and the use of element-specific X-ray magnetic reflectivity and x-ray resonant scattering to probe buried interfaces, both of importance in understanding the fundamental physics of exchange bias. In the latter case, a complex magnetic interfacial configuration in Fe/MnPd, consisting of a 2-monolayer-thick induced ferromagnetic region, and pinned uncompensated Mn moments that reach far deeper (~13 Å), both in the antiferromagnet, were found. Such epitaxial EB samples also show in-plane reorientation transitions, determined by the competition between the interface exchange coupling and the intrinsic uniaxial energies, and is driven by the temperature, as well as the thickness of MnPd and Fe layers. Complementing these results, work on multilayers show that perpendicular EB arise from a complex interplay between unidirectional anisotropy at the terminating FM/AFM interface, the perpendicular anisotropy of the FM/nonmagnet(NM) multilayer stack and the overall magnetostatic energy of the structure. Collaborative work with Prof. R. Stamps (UWA) in modeling and analysis of slow-dynamics, using an inductive ferromagnetic resonance technique, were also carried out. Further details of our research is presented below broadly in five thematic areas. Overall, this research allowed us to obtain a deeper understanding of the range of related magnetic phenomena and establish pathways for potential technological applications of these thin film and patterned heterostructures.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Machine Learning for Automated Weld Quality Monitoring and Control
Resistance Spot Welding (RSW) is a critical process in the automotive industry, valued for its cost-effectiveness, short cycle time, and robustness. However, achieving consistent high-quality joints remains challenging due to the complex interplay of various factors, like materials, processes, and manufacturing uncertainties, etc. Under the collaborative project between Oak Ridge National Laboratory (ORNL) and General Motors (GM), we have developed a robust and expansible machine learning (ML) framework aimed at enhancing quality control in RSW. By harnessing the power of machine learning, we have developed the ability to ensure every aspect of the welding process, from the initial process design stage to the final weld joint quality. The framework operates by analyzing a variety of data streams, including in-line process signals, process parameters, materials, and postprocessed weld joint data. Through this analysis, the models have been trained to detect deviations from optimal quality standards, leveraging their ability to identify signature data patterns and anomalies within in-line signals and construct complex correlations between these signals and weld quality parameters. Meanwhile, the machine learning framework is designed to adapt to a variety of materials, including high strength steels and aluminum alloys, etc. Its flexible architecture facilitates the incorporation of diverse data sources and features, enabling precise modeling and prediction across a broad range of material properties and weld quality variables. The expansible ML frameworks represent a promising transformation in weld quality monitoring and control, empowering industry to achieve high levels of efficiency, consistency, and reliability in manufacturing.
42 ENGINEERING↗
The real-time data processing and acquisition system for Project 8 Phase II
In Phase II of the Project 8 neutrino mass experiment, electrons from the decays of tritium or 83m Kr are detected via their ≈26 GHz cyclotron radiation while contained within a circular waveguide. The signal from a given electron is characterized as a brief chirp, lasting ≲10 ms and changing in frequency by ≲1 MHz/ms. To detect these signals, the Project 8 collaboration developed a Data Acquisition (DAQ) system tailored to the signal properties. The DAQ is responsible for simultaneously selecting up to three 100 MHz-wide frequency windows to study, detect, and trigger on likely signals from different electron kinetic energies, and for writing the relevant data to disk. Finally, we describe the Phase II DAQ system in detail and address how the system was used for data-taking operations.
Data acquisition↗
Sensitivity Tests of Aluminum Precipitate Preparation Methods on Head Loss through Debris Beds on a Sump Screen
During a Loss-of-Coolant Accident (LOCA) in Pressurized Water Reactors (PWRs), buffered borated water as a coolant from the Refueling Water Storage Tank (RWST) will be injected into the primary loop to cool down the core depending on the break size. For long-term cooling, the coolant will be collected in the containment sump. Then, the Emergency Core Cooling System (ECCS) will pump the coolant through the sump strainers into the reactor. During this phase, buffered borated water produces chemical precipitate by reacting with the structural materials in the containment. Chemical effects evaluated as part of Generic Safety Issue 191 (GSI-191) resolution studies are broadly defined as any chemically induced phenomenon that affects ECCS performance. Initial chemical effects studies jointly sponsored by the Nuclear Regulatory Commission (NRC) and Industry collaborators led to a Westinghouse Owners Group (WOG) study that provided bases for deterministic quantification of chemical effects. The WCAP-16530-NP developed protocols to produce Aluminum Oxyhydroxide (AlOOH), Calcium Phosphate, and Sodium Aluminum Silicate (SAS). The surrogate generation protocol used the metal salt (aluminum nitrate and calcium acetate) unlike post-LOCA accident scenarios where metals leach into a buffered borated solution. Bahn et al. demonstrated that the WCAP-16530-NP SAS precipitate did not produce as much head loss as the WCAP-16530-NP AlOOH precipitate, thus, the present study focused on the effect of AlOOH precipitate on head loss through a fibrous debris bed. In the past, most of the tests were conducted in high approach velocity conditions, approximately 0.03 m/s. After modifications of sump strainer size in PWRs, the approach velocity to the sump strainer was reduced by an order of magnitude, approximately 0.001 ∼ 0.003 m/s. Howe et al. and Kim et al. conducted several head loss tests at the approach velocity of 0.003 m/s. In the present study, an approach velocity of 0.0006 m/s was selected for an extremely slow power plant condition. A PCI strainer design was used as previous head loss tests and debris bypass tests conducted by Lee et al. Three different chemical precipitate preparation methods were used in this study. The additional head loss of the debris bed caused by those chemical precipitates was investigated. The debris bed was produced with NUKON{sup R} fiberglass thermal insulator and additional particulates including dirt, Tin powder, acrylic powder, and Calcium silicate (CalSil). (authors)
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗