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At least 73 records · Page 4

Materials Inventory Database for the Light Water Reactor Sustainability Program

Scientific research involves the purchasing, processing, characterization, and fabrication of many sample materials. The history of such materials can become complicated over their lifetime – materials might be cut into pieces or moved to various storage locations, for example. A database with built-in functions to track these kinds of processes facilitates well-organized research. The Material Inventory Database Accounting System (MIDAS) is an easy-to-use tracking and reference system for such items. The Light Water Reactor Sustainability Program (LWRS), which seeks to advance the long-term reliability and productivity of existing nuclear reactors in the United States through multiple research pathways, proposed MIDAS as an efficient way to organize and track all items used in its research. The database software ensures traceability of all items used in research using built-in functions which can emulate actions on tracked items – fabrication, processing, splitting, and more – by performing operations on the data. MIDAS can recover and display the complete history of any item as a simple report. To ensure the database functions suitably for the organization of research, it was developed alongside a specific experiment to test accident tolerant nuclear fuel cladding under the LWRS Advanced Light Water Reactor Nuclear Fuels Pathway. MIDAS kept track of materials used in this experiment from receipt at the laboratory through all processes, test conduct and, ultimately, post-test analysis. By the end of this process, the database proved to be right tool for this program. The database software will help LWRS more efficiently conduct research experiments, from simple characterization tests to in-reactor experiments. Furthermore, MIDAS is a universal tool that any other research team could use to organize their material inventory.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Quantitative study of the effect of grain boundary parameters on the slip system level Hall-Petch slope for basal slip system in Mg-4Al

Several theoretical studies have reported that the geometry and structure of grain boundaries in polycrystalline materials could impose a significant effect on the Hall-Petch slope. However, experimental observations are primarily limited by the ability of the techniques to accurately quantify the grain boundary strength and validate these theoretical models. Using high-resolution electron backscatter diffraction (HR-EBSD), the local stress tensor ahead of a slip band blocked by a grain boundary was quantified and coupled with a continuum dislocation pile-up model to assess the barrier strength of specific grain boundaries to specific slip systems, referred to as micro-Hall-Petch coefficient. For basal slip system in a deformed Mg-4Al alloy, the micro-Hall-Petch coefficient ($k^{basal}_{μ}$) varied significantly, from 0.054 to 0.184 MPa - m 1/2 for nine different grain boundaries. These results were correlated with geometric descriptors of the respective grain boundaries, with three-dimensional GB profile additionally measured via focused ion beam milling. It was found that the angle between the two slip plane traces on the grain boundary plane was the most sensitive parameter affecting $k^{basal}_{μ}$, followed by the angle between the slip directions. A functional form for calculation of $k^{basal}_{μ}$ depending on these two angles is proposed to augment crystal plasticity constitutive models with slip resistance dependent on some measure of the grain size. The method allows a new pathway to calibrate grain size strengthening parameters in crystal plasticity models, allowing further computational investigations of the interrelationship between texture, grain morphology, and the Hall Petch effect.

36 MATERIALS SCIENCE↗

Free Energy Calculations of Crystalline Hard Sphere Complexes Using Density Functional Theory

Recently developed fundamental measure density functional theory (FMT) is used to study binary hard sphere (HS) complexes in crystalline phases. By comparing the excess free energy, pressure and phase diagram, we show that the fundamental measure functional yields good agreements to the available simulation results of AB, AB 2 and AB 13 crystals. Additionally, we use this functional to study the HS models of five binary crystals, Cu 5 Zr(C15 b ), Cu 51 Zr 14 (β), Cu 10 Zr 7 (φ), CuZr(B2) and CuZr 2 (C11 b ), which are observed in the Cu-Zr system. The FMT functional gives well behaved minimum for most of the hard sphere crystal complexes in the two dimensional Gaussian space, namely a crystalline phase. However, the current version of FMT functional (white Bear) fails to give a stable minimum for the structure Cu 10 Zr 7 (φ). We argue that the observed solid phases for the HS models of the Cu-Zr system are true thermodynamic stable phases and can be used as a reference system in perturbation calculations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Regulation of Dynamical Systems to Optimal Solutions of Semidefinite Programs: Algorithms and Applications to AC Optimal Power Flow

This paper considers a collection of networked nonlinear dynamical systems, and addresses the synthesis of feedback controllers that seek optimal operating points corresponding to the solution of pertinent network-wide optimization problems. Particular emphasis is placed on the solution of semidefinite programs (SDPs). The design of the feedback controller is grounded on a dual e-subgradient approach, with the dual iterates utilized to dynamically update the dynamical-system reference signals. Global convergence is guaranteed for diminishing stepsize rules, even when the reference inputs are updated at a faster rate than the dynamical-system settling time. The application of the proposed framework to the control of power-electronic inverters in AC distribution systems is discussed. The objective is to bridge the time-scale separation between real-time inverter control and network-wide optimization. Optimization objectives assume the form of SDP relaxations of prototypical AC optimal power flow problems.

24 POWER TRANSMISSION AND DISTRIBUTION↗

Suggested Modifications for Bifacial Capacity Testing

Capacity tests such as those described in ASTM 2848 and IEC 61724-2 are widely used during the contracting and acceptance testing of photovoltaic systems. With the increasing deployment of bifacial photovoltaic modules, there is a need to develop a standardized approach to capacity test these systems. Although variability and bias error were inherently higher for the measured capacity of bifacial systems, they could be reduced to a level consistent with the monofacial reference system by appropriate incorporation of rear irradiance—either measured or modeled. Three field installations provided bifacial system capacity that was measured with a mean bias error and standard deviation within 1% over the 2–10-month observation period. Capacity test accuracy could be improved further by using the measured back-of-module temperature and the IEC 61724-2 test method for well curated systems.

41 EE - Solar Energy Technologies Office (EE-4S)↗

Dose reduction using a dynamic, piecewise-linear attenuator

Purpose: The authors recently proposed a dynamic, prepatient x-ray attenuator capable of producing a piecewise-linear attenuation profile customized to each patient and viewing angle. This attenuator was intended to reduce scatter-to-primary ratio (SPR), dynamic range, and dose by redistributing flux. In this work the authors tested the ability of the attenuator to reduce dose and SPR in simulations. Methods: The authors selected four clinical applications, including routine full field-of-view scans of the thorax and abdomen, and targeted reconstruction tasks for an abdominal aortic aneurysm and the pancreas. Raw data were estimated by forward projection of the image volume datasets. The dynamic attenuator was controlled to reduce dose while maintaining peak variance by solving a convex optimization problem, assuminga priori knowledge of the patient anatomy. In targeted reconstruction tasks, the noise in specific regions was given increased weighting. A system with a standard attenuator (or “bowtie filter”) was used as a reference, and used either convex optimized tube current modulation (TCM) or a standard TCM heuristic. The noise of the scan was determined analytically while the dose was estimated using Monte Carlo simulations. Scatter was also estimated using Monte Carlo simulations. The sensitivity of the dynamic attenuator to patient centering was also examined by shifting the abdomen in 2 cm intervals. Results: Compared to a reference system with optimized TCM, use of the dynamic attenuator reduced dose by about 30% in routine scans and 50% in targeted scans. Compared to the TCM heuristics which are typically used withouta priori knowledge, the dose reduction is about 50% for routine scans. The dynamic attenuator gives the ability to redistribute noise and variance and produces more uniform noise profiles than systems with a conventional bowtie filter. The SPR was also modestly reduced by 10% in the thorax and 24% in the abdomen. Imaging with the dynamic attenuator was relatively insensitive to patient centering, showing a 17% increase in peak variance for a 6 cm shift of the abdomen, instead of an 82% increase in peak variance for a fixed bowtie filter. Conclusions: A dynamic prepatient x-ray attenuator consisting of multiple wedges is capable of achieving substantial dose reductions and modest SPR reductions.

61 RADIATION PROTECTION AND DOSIMETRY↗

Integral and Separate Effects Tests for Thermal Hydraulics Code Validation for Liquid-Salt Cooled Nuclear Reactors

The objective of the 3-year project was to collect integral effects test (IET) data to validate the RELAP5-3D code and other thermal hydraulics codes for use in predicting the transient thermal hydraulics response of liquid salt cooled reactor systems, including integral transient response for forced and natural circulation operation. The reference system for the project is a modular, 900-MWth Pebble Bed Advanced High Temperature Reactor (PB-AHTR), a specific type of Fluoride salt-cooled High temperature Reactor (FHR). Two experimental facilities were developed for thermal-hydraulic integral effects tests (IETs) and separate effects tests (SETs). The facilities use simulant fluids for the liquid fluoride salts, with very little distortion to the heat transfer and fluid dynamics behavior. The CIET Test Bay facility was designed, built, and operated. IET data for steady state and transient natural circulation was collected. SET data for convective heat transfer in pebble beds and straight channel geometries was collected. The facility continues to be operational and will be used for future experiments, and for component development. The CIET 2 facility is larger in scope, and its construction and operation has a longer timeline than the duration of this grant. The design for the CIET 2 facility has drawn heavily on the experience and data collected on the CIET Test Bay, and it was completed in parallel with operation of the CIET Test Bay. CIET 2 will demonstrate start-up and shut-down transients and control logic, in addition to LOFC and LOHS transients, and buoyant shut down rod operation during transients. Design of the CIET 2 Facility is complete, and engineering drawings have been submitted to an external vendor for outsourced quality controlled construction. CIET 2 construction and operation continue under another NEUP grant. IET data from both CIET facilities is to be used for validation of system codes used for FHR modeling, such as RELAP5-3D. A set of numerical models were developed in parallel to the experimental work. RELAP5-3D models were developed for the salt-cooled PB-AHTR, and for the simulat fluid CIET natural circulation experimental loop. These models are to be validated by the data collected from CIET. COMSOL finite element models were used to predict the temperature and fluid flow distribution in the annular pebble bed core; they were instrumental for design of SETs, and they can be used for code-to-code comparisons with RELAP5-3D. A number of other small SETs, and numerical models were constructed, as needed, in support of this work. The experiments were designed, constructed and performed to meet CAES quality assurance requirements for test planning, implementation, and documentation; equipment calibration and documentation, procurement document control; training and personnel qualification; analysis/modeling software verification and validation; data acquisition/collection and analysis; and peer review.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Coatings and Process Development for Reduced Energy Automotive OEM Manufacturing Final Technical Report

The project team successfully developed a new low-temperature coating system that achieves performance, durability, and appearance requirements for an Automotive Original Equipment Manufacturer paint system. This coating system is compatible with current OEM manufacturing paint lines, allowing application to existing manufacturing locations. The new coating system can also save capital expenses for new lines or renovations of existing lines. The new paint system enable energy savings and operational expense savings. DURR has designed a reference system that can serve as the starting point for new or retrofit paint line upgrades to this low temperature coating system. NDSU has developed and demonstrated the value of high-throughput screening for polymers and cure performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

IoT-Based Comfort Control and Fault Diagnostics System for Energy-Efficient Homes

This project studies an Internet of Things (IoT)-based comfort control and fault diagnostics system (referred as iComfort in this report) for energy-efficient homes. The system delivers an occupant-comfort-oriented thermal environment adaptive to fault scenarios and achieves HVAC energy savings in a cost-effective and straightforward way. This smart iComfort home system consists of the following key features. 1) Cost-effectiveness and scalability of the entire hardware and software system: The system includes low-cost temperature, humidity, and airflow sensors, and a Raspberry Pi-based local hub that interfaces with the cloud and IoT-enabled devices. The cost is low, not only for sensors, but also the costs associated with sensor installation, system setup and commissioning, data communication and storage, and data analytics (e.g., the development of automated fault detection and diagnosis (AFDD), as well as adaptive control strategies that are both computationally efficient and practical to implement). 2) Energy performance and user satisfaction: The system delivers user satisfaction and energy savings. This includes a) ease of use, b) optimal occupant thermal comfort, and c) accurate system feedback (e.g., low false alarm of AFDD strategies). 3) Favorable demonstrated prototype performance: The prototype tested at the Pacific Northwest National Laboratory (PNNL) Lab Homes demonstrates the accuracy of fault detections and diagnoses and shows thermal comfort improvement and energy savings through adaptive and optimal HVAC operations.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Suggested Modifications for Bifacial Capacity Testing: Preprint

Capacity tests such as those described in ASTM 2848 and IEC 61724-2 are widely used during the contracting and acceptance testing of PV systems. With the increasing deployment of bifacial PV modules, there is a need to develop a standardized approach to capacity test these systems. Although variability and bias error was inherently higher for the measured capacity of bifacial systems, it could be reduced to a level consistent with the monofacial reference system by appropriate incorporation of rear irradiance- either measured or modeled. Three field installations provided bifacial system capacity that was measured with a mean bias error and standard deviation within 1% over the 2-10 month observation period. Capacity test accuracy could be improved further by utilizing measured back-of-module temperature and the IEC 61724-2 test method.

14 SOLAR ENERGY↗

Influence of Long-Range Forces on the Transition States and Dynamics of NaCl Ion-Pair Dissociation in Water

We study NaCl ion-pair dissociation in a dilute aqueous solution using computer simulations both for the full system with long-range Coulomb interactions and for a well-chosen reference system with short-range intermolecular interactions. Analyzing results using concepts from Local Molecular Field (LMF) theory and the recently proposed AI-based analysis tool “State predictive information bottleneck” (SPIB), we show that the system with short-range interactions can accurately reproduce the transition rate for the dissociation process, the dynamics for moving between the underlying metastable states, and the transition state ensemble. Contributions from long-range interactions can be largely neglected for these processes because long-range forces from the direct interionic Coulomb interactions are almost completely canceled (>90%) by those from solvent interactions over the length scale where the transition takes place. Thus, for this important monovalent ion-pair system, short-range forces alone are able to capture detailed consequences of the collective solvent motion, allowing the use of physically suggestive and computationally efficient short-range models for the dissociation event. Here, we believe that the framework here should be applicable to disentangling mechanisms for more complex processes such as multivalent ion disassociation, where previous work has suggested that long-range contributions may be more important.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Molecular dynamics simulations of concentration-dependent defect production in Fe-Cr and Fe-Cu alloys

Molecular dynamics simulations are conducted to study the effects of alloying elements on the primary damage behaviors in three Fe-based ferritic alloy systems: (1) a Fe-Cr system in which the heat of mixing changes its sign with the Cr concentration; (2) a Fe-Cu system that has a positive heat of mixing; and (3) an ideal but artificial Fe-Cr system that has a zero heat of mixing, which is used as a reference system to investigate solute interstitial formation based on probability. It is found that in these alloys, the solute type and concentration do not have a significant effect on the total number of surviving Frenkel pairs. However, the fraction of solute interstitials has distinct behaviors. In Fe-Cr, the Cr interstitial fraction is much higher than the Cr solute concentration and the Cr interstitial production efficiency decreases with the increasing Cr concentration. By contrast, in Fe-Cu, Cu interstitials are barely produced. In the ideal alloy, the solute interstitial fraction is close to the solute concentration. The defect formation energies in both dilute and concentrated alloys, interstitial binding energies, liquid diffusivities of Fe and solute atoms, and heat of mixing have been calculated for both Fe-Cr and Fe-Cu alloys. Among them, we find that the relative thermodynamic stability between Fe self-interstitials and solute interstitials plays the most important role in the solute interstitial production behaviors. The decrease of Cr interstitial production efficiency with increasing Cr concentration can be explained by the probability distribution functions of solute interstitial formation energy in concentrated alloys.

Zhang, Yaxuan↗

Cyber Security Concerns for Sharing Distributed Antenna Systems

Wireless access to data is a challenge for environments with poor radio frequency coverage such as nuclear power plants. An 802.11 Wi-Fi data network is often not a cost-effective solution not a cost-effective solution due to the requirement for extensive antenna outlays in large nuclear facilities and poor signal penetration due to thick concrete walls. Combining commercial Long-Term Evolution (LTE) with an existing distributed antenna system’s (DAS) resources and infrastructure is an attractive solution due to and lower cost of implementation and likely coverage increases. A 2017 technical report by EPRI has demonstrated that multiple systems such as Land Mobile Radio (LMR) and LTE can be operated using the same DAS and by sharing the leaky coaxial cabling and indoor antenna systems (Reference 1). Since the radio frequency (RF) bands used by the two wireless systems are specified to be non-overlapping, it is believed that the systems are isolated from each other. No extensive analysis has been conducted to determine whether RF signals from one system sharing antennas and coaxial cable can influence another. This paper investigates the assumption of isolation between the two wireless systems and provides recommendations for future needed work to identify specific vulnerabilities and potential mitigations.

97 MATHEMATICS AND COMPUTING↗

ABSOLUTE PROPER MOTIONS OUTSIDE THE PLANE (APOP)—A STEP TOWARD THE GSC2.4

We present a new catalog of absolute proper motions and updated positions derived from the same Space Telescope Science Institute digitized Schmidt survey plates utilized for the construction of Guide Star Catalog II. As special attention was devoted to the absolutization process and the removal of position, magnitude, and color dependent systematic errors through the use of both stars and galaxies, this release is solely based on plate data outside the galactic plane, i.e., |b|≥27°. The resulting global zero point error is less than 0.6 mas yr{sup -1}, and the precision is better than 4.0 mas yr{sup -1} for objects brighter than R{sub F} = 18.5, rising to 9.0 mas yr{sup -1} for objects with magnitudes in the range 18.5 < R{sub F} < 20.0. The catalog covers 22,525 square degrees and lists 100,774,153 objects to the limiting magnitude of R{sub F} ~ 20.8. Alignment with the International Celestial Reference System was made using 1288 objects common to the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths. As a result, the coordinate axes realized by our astrometric data are believed to be aligned with the extragalactic radio frame to within ±0.2 mas at the reference epoch J2000.0. This makes our compilation one of the deepest and densest ICRF-registered astrometric catalogs outside the galactic plane. Although the Gaia mission is poised to set the new standard in catalog astronomy and will in many ways supersede this catalog, the methods and procedures reported here will prove useful to remove astrometric magnitude- and color-dependent systematic errors from the next generation of ground-based surveys reaching significantly deeper than the Gaia catalog.

79 ASTRONOMY AND ASTROPHYSICS↗

Use Case Realization Report: UCR-02.08 System Refines Event Location

This architecturally significant use case describes how the System refines event hypothesis location solutions. The System locates events by finding the event location minimizing the difference between signal detection feature measurements and signal detection feature predictions (see 'System Measures Signal Features' UC). The System references both empirical knowledge from past events and geophysical models to form the signal detection feature predictions. The System also computes an uncertainty bound for each event hypothesis location solution describing a region bounding the event hypothesis' hypocenter and origin time at a particular confidence level. The System creates a variety of location solutions for each event hypothesis. These location solutions vary from one another in either the input parameters the System uses or in the location solution components the System restrains to fixed values (e.g. depth) during event location calculations. The System computes location solutions using input parameters configured by the System Maintainer (see ‘Configures Processing Components’ UC). The Analyst has the option to override input parameters originally configured by the System Maintainer (see 'Refines Event Location' UC). This use case is architecturally significant due to the processing and memory resource consumption of 3D earth model calculations.

97 MATHEMATICS AND COMPUTING↗

Lessons learned from the design and operation of a small-scale cross-flow tidal turbine

In 2023, a first-generation prototype of a small-scale marine current turbine was operated in Sequim Bay, Washington (USA) for 141 days. The system, referred to as the Turbine Lander, was the product of a laboratory-to-field effort to develop a system that enables enhanced ocean sensing or vehicle recharge in remote, energetic settings. The turbine consists of a vertical-axis, cantilevered rotor (1.19 m x 0.85 m) with four foils installed on a gravity foundation. A broader range of constraints including the deployment strategy, site characteristics, and estimated loads, drove the system’s design. This work presents the design, characterization, operation, and post-recovery engineering assessment of the Turbine Lander. Pre-deployment characterization efforts yielded a peak power coefficient of approximately 0.3 for the rotor, although system losses resulted in much lower water-to-wire efficiencies under most operating conditions. The results demonstrate the importance of co-design among key components of the powertrain and control systems to achieve acceptable system efficiency across operating conditions.

Co-design↗

Convergence Rate of Model Reference Adaptive Control with Application to Building HVAC Systems

Model reference adaptive control (MRAC) has been studied for decades and successfully applied in multiple areas, including heating, ventilation, and air conditioning (HVAC) systems for buildings. MRAC is efficient in capturing the time-varying characteristics of buildings' indoor temperatures and outdoor weather environments. In this paper, the rate of convergence of MRAC is investigated, where a direct adaptive control with temperature set point reference tracking is used to regulate the indoor temperatures for buildings. Numerical results show that by controlling the HVAC systems of residential buildings using MRAC, the indoor temperatures converge Q-sublinearly to the desired temperature set points. In addition, the rate of convergence for MRAC is compared with a baseline adaptive model-free control method.

Wu, Tumin↗

An Experimental Investigation of Distributed Acoustic Sensing (DAS) on Lake Ice

A vibration-sensitive, Distributed Acoustic Sensor (DAS) array, using fiber-optic cables, was deployed in a triangularly shaped geometry on the frozen surface of Lake Mendota in Madison, Wisconsin, USA. The purpose of the array and testing program was to analyze the DAS response and to utilize the high spatial density of the distributed array for system response characterization in a well-constrained, small, surface array. A geophone array was also deployed to provide a reference system. The design of the array allowed us to assess the response of DAS with respect to distance from the seismic sources, the degradation of the response with length of the cable, the directivity of the fiber response with respect of the direction of the particle motion, and the quality of the signal with respect to cable type. The DAS array was examined for different cable constructions and orientations relative to the source propagation direction. Tight-buffered and loose-tube fiber-optic cable constructions were used, with both having good signal responses when well-coupled to the ice. In general, the tight-buffered cable was better suited for DAS applications. Directional sensitivity of the DAS was also inspected for several directions of wave propagation and particle motion. The results showed that the strongest DAS signals were recorded when the direction of the fiber was oriented parallel to the direction of particle motion. Lastly, the DAS and geophone data sets were examined together to qualitatively determine, in conjunction with established DAS best practices, how the high spatial density offered by DAS could improve results over traditional point sensor arrays in certain situations.

15 GEOTHERMAL ENERGY↗