LGAD (AC-LGAD) detector R&D status and plan at LANL
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Atomic, Nuclear and Particle Physics↗
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Quantifying Properties for a Mechanistic, Predictive Understanding of Aqueous Impact on Aging of Medium and Low Voltage AC and DC Cabling in Nuclear Power Plants
To address the gap in knowledge in understanding degradation in relevant service conditions, this project aimed to develop a mechanistic, predictive model of medium and low voltage cable failure based on the primary environmental degradation parameters of aqueous immersion time, temperature, and the oxidation extent. To do so, we took a two-fold approach toward evaluating degradation as related to the aqueous condition. First, we evaluated the chemical, mechanical, and electrical properties of polymers that comprise the cabling insulation under varied aqueous conditions at different temperatures. Secondly, we evaluated the performance of insulation materials under similar accelerated aging conditions in addition to the dielectric breakdown of the cabling under submersion conditions. Thermal oxidation and immersion of LDPE thin films were done using a Parr vessel and the extent of oxidation was monitored using the carbonyl index from ATR-FTIR spectrum, a ratio quantifying the carbonyl functionality produced on the LDPE film surface. Increasing the temperature, oxidation time, and oxygen pressure increased the water-vapor permeability and the carbonyl content. Thermogravimetric analysis of the films confirmed that there is indeed an initial weight loss of the smaller molecular weight molecules and volatiles. At higher temperatures, there is a secondary mass loss. Up to 70°C, the mass loss curves were similar until 80°C, when the aged films decreased at a much greater rate with respect to increasing temperature. This was seen in the 10, 50, 90% weight loss temperatures. The mechanical properties of sheet PP and HDPE as well as injection molded LDPE, HDPE, HDPP dog bones were plotted with respect to the time spent in the Parr vessel during thermal oxidation. For the sheet PP and HDPE, the UTS and the modulus of elasticity decreased while the elongation increased. The injection-molded LDPE, HDPE, and HDPP dog bones experienced a similar trend where the changes in the properties were within experimental uncertainty. This analysis of LDPE in dry and immersive oxygen-rich environments is an important baseline for future experiments looking at other degradation mechanisms. A predictive aging model for low-density polyethylene insulative cable housings was developed. This model revealed a combination of physical and chemical processes which lead to an increase in permeability and a decrease in strength of the insulator. In creating this predictive model, a gap of knowledge in the literature was revealed in two areas: understanding how the crystallinity of a polymer changes with time and visualizing the predicted pores formed through the insulator which leads to failure. Developing and using an adapted ATR-FTIR method, crystallinity was monitored and compared to bulk crystallinity found via DSC. Inhomogeneity in crystallinity changes were observed but the FTIR method but was found to be less reliable. Pore visualization was found utilizing electrical impedance spectroscopy saturated aged polyethylene films with synthesized citrate-capped gold nanoparticles, and chloroauric acid precursor. results indicate a decreasing impedance of the polyethylene films caused by the transport of ions through the film. SEM imaging was then performed for elemental analysis of the films and counter electrodes for the presence of ions. Chloride and gold ions were detected; however, no nanoparticles were found. This gives an estimated pore size of at least 0.3 nm through the aged film. Cyclic submergence of polyethylene and polypropylene in aqueous solutions of copper sulfate and Harrison’s solution were examined. It was discovered that aging in these mixed conditions and at 90°C did cause a small, yet significant increase to tensile strength for both unaged polyethylene and polypropylene. The PE and PP in cycled and submerged conditions did not have tensile strengths significantly different from dry-aged after 16 weeks. For both solutions, it was determined that capacitance increases with both water tree depth and cable temperature and is relatively independent of changing water tree AR. As for resistance, there is no apparent change between depth percentages of 10 and 80 for both solutions. This is because the water tree has not yet entered the conductor and thus there is no shorting current flowing through the tree yet. Between 80 and 100% water tree depth, it is observed that for both solutions there is a rapid decrease in resistance because the tree is now impacting the conductor shield and allowing shorting current to flow through it. The relationship between resistance and temperature was found to be inversed. As temperature increases, resistance decreases for both water tree solutions with distilled water having the most apparent difference across the range of temperatures simulated. With regards to water tree AR, resistance was found to be relatively independent at depth percentages of 10, 50, and 70, but there was some relationship at 100% depth for both solutions. At this depth, as water tree AR increased, resistance was found to also increase. Through the examination of voltage and electric field distribution plots, it was confirmed for EPR cables that increasing water tree depth leads to increasing distortion. The increase in shorting current at 100% depth for aqueous copper sulfate compared to distilled water was also visualized. Lastly, the relationship between shorting current and temperature for narrow water trees was visualized and validated using the distribution plots. This study has led to a better understanding of the effect of cable temperature, water tree solution, and geometry of the tree region on cable degradation. Furthermore, this study has documented simulation results of water tree degradation in EPR MV cables, which had been previously lacking in information. Future work in this area will add frequency into the mix and examine what effect it has on the rate of cable degradation as a result of water treeing. To compliment the work being carried by UMD on different polymer chemistries, harvested medium voltage (MV) cables were selected for accelerated aging study at ORNL. These medium voltage cables are representative of the vintages and materials that are currently in use at existing nuclear power plants (NPPs). These cables were immersed in water at 90°C and energized for a period of two years at elevated voltage. Partial discharge was measured during this period of time to track potential degradation. Unfortunately, due to the absence of failure, the extent of integration between the UMD techniques and the harvested MV insulation was limited. However, based on the findings and from the UMD research in the previous sections on polyethylene and polypropylene, follow-on characterization for harvested MV cable insulation should focus on sample preparation to take advantage of the UMD techniques to better understand mechanistic degradation in MV cable insulations. This would include: 1.) Utilization of solutions and impedance measurement insulation to track permeability in harvested and accelerated aging insulation samples, 2.) Adaptation of gold nanoparticle synthesis for electrical impedance spectroscopy with supporting SEM characterization to study pore formation in harvested and accelerated aged insulation samples, & 3.) ATR-FTIR crystallinity with multiple temperature dependent harvested MV cable insulation under different air and submerged accelerated aging. In addition, low voltage dielectric spectroscopy and high voltage dissipation factor, tan δ, could be implemented as a condition monitoring tool for harvested MV cable insulation in submerged environments.
24 POWER TRANSMISSION AND DISTRIBUTION↗
LGAD (AC-LGAD) detector R&D at LANL for the future Electron-Ion Collider
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Atomic, Nuclear and Particle Physics↗
BTRAN AC Solid State Circuit Breaker
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24 POWER TRANSMISSION AND DISTRIBUTION↗
Final Technical Report - A Novel Radium-Selective Separation Technique to Improve the Production of 225 Ac for Cancer Immunotherapy
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Drera, Saleem↗
Y separations Experiments Talk_ACS_2023
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Chemistry - Radiation chemistry, radiochemistry, a↗
Comparison of Sandia?s JAWS system to conventional AC-DC difference measurements .
Abstract not provided.
Johnson, Raegan↗
The National Transmission Planning Study: Chapter 4: AC Power Flow Analysis for 2035 Scenarios
The National Transmission Planning Study (NTP Study) was led by the U.S. Department of Energy's Grid Deployment Office, in partnership with the National Renewable Energy Laboratory and Pacific Northwest National Laboratory. The study sought to develop new national grid-scale planning tools and methods that can be used by industry, especially when planning for interregional transmission capacity needs; identify potential transmission solutions that will provide broad-scale benefits to electric customers under a wide range of potential futures; inform planning processes for regional and interregional transmission; and identify interregional and national strategies to maintain grid reliability as the grid transitions, including to a reliance on low- and zero-carbon energy resources. The NTP Study is presented as a collection of six chapters.
ENERGY PLANNING, POLICY, AND ECONOMY,POWER TRANSMI↗
Control, Fault Management, and Grid Support Functionality of an MV AC-DC Solid State Transformer based EV Extreme Fast Charging Station
Electric vehicles (EVs) have become increasingly popular in recent times while revolutionizing the consumer and commercial transportation market. The development of charging infrastructure has become one of the priorities for increasing the adoption of EVs. Extreme fast charging (XFC) technology can reduce the so-called ’range anxiety’ of consumers as they significantly reduce the charging time. With the advent of wide band-gap (WBG) power devices and improvement in power electronic converters, medium voltage (MV) solid state transformer (SST) based XFC system has the potential to replace the traditional XFC stations because of the lower footprint, ease of installation, enhanced control feature, and better system efficiency. The control system design is one of the critical aspects of the SST development process. Careful consideration and detailed analysis are required to find out suitable control method for the SST based on its topology among different centralized and decentralized control architectures. Also, the control parameters selection and potential improvement to the transient response of the controller ought to be investigated. Another major concern of the SST is different types of internal fault which reduces the overall reliability of the XFC system. As a result, designing a robust protection system is essential. Among different fault modes, open circuit switch faults have received significant attention as an active research area because of their likelihood and severe effects on converters. Therefore, the power stages used in the XFC system require functional and accurate open circuit switch fault management methods. An equally significant aspect of this SST based XFC is its compatibility in a microgrid where there is no synchronous generator present. When the grid is not available, the XFC SSTs can provide grid forming capability and continue supplying the critical loads in islanded mode. The transition between grid connected and islanded mode, especially the grid resynchronization process has to be carefully performed for the safety of the microgrid components. The challenges posed by the aforementioned issues have inspired the work done in this dissertation. Here, a 13.2 kV, 1 MVA, AC/DC SST for the XFC system is examined and a comparative analysis is conducted to select the control architecture based on feasibility of implementation and performance. A detailed control parameter design process is demonstrated considering the sensor dynamics and delay. The selected decentralized control method is augmented by introducing a novel sensor-less load current feedforward method to provide better voltage regulation at the DC bus during a change of load. Next, in the fault management section, a hierarchical failure mode effect analysis (FMEA) is proposed to enable a systematic design of the internal fault protection of the XFC SST as there are limited examples in the literature regarding the analysis of the safety and design of the protection of a power electronic converter system. Novel open circuit switch fault management methods for the converters in the system are presented. Finally, XFC SST based MV microgrid operations in grid connected mode and islanded mode are explored. A secondary control method for grid resynchronization is presented and a design process of control parameters is shown to ensure the stability of the secondary voltage and frequency regulation.
30 DIRECT ENERGY CONVERSION↗
Materials Data on CsAc3 by Materials Project
CsAc3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Cs is bonded to twelve Ac atoms to form CsAc12 cuboctahedra that share corners with six equivalent CsAc12 cuboctahedra, corners with twelve AcCs4Ac8 cuboctahedra, edges with eighteen AcCs4Ac8 cuboctahedra, faces with eight equivalent CsAc12 cuboctahedra, and faces with twelve AcCs4Ac8 cuboctahedra. There are six shorter (4.15 Å) and six longer (4.22 Å) Cs–Ac bond lengths. There are three inequivalent Ac sites. In the first Ac site, Ac is bonded to four equivalent Cs and eight Ac atoms to form distorted AcCs4Ac8 cuboctahedra that share corners with four equivalent CsAc12 cuboctahedra, corners with fourteen equivalent AcCs4Ac8 cuboctahedra, edges with six equivalent CsAc12 cuboctahedra, edges with twelve AcCs4Ac8 cuboctahedra, faces with four equivalent CsAc12 cuboctahedra, and faces with sixteen AcCs4Ac8 cuboctahedra. There are a spread of Ac–Ac bond distances ranging from 4.02–4.40 Å. In the second Ac site, Ac is bonded to four equivalent Cs and eight Ac atoms to form distorted AcCs4Ac8 cuboctahedra that share corners with four equivalent CsAc12 cuboctahedra, corners with fourteen AcCs4Ac8 cuboctahedra, edges with six equivalent CsAc12 cuboctahedra, edges with twelve AcCs4Ac8 cuboctahedra, faces with four equivalent CsAc12 cuboctahedra, and faces with sixteen AcCs4Ac8 cuboctahedra. There are a spread of Ac–Ac bond distances ranging from 4.02–4.40 Å. In the third Ac site, Ac is bonded to four equivalent Cs and eight Ac atoms to form distorted AcCs4Ac8 cuboctahedra that share corners with four equivalent CsAc12 cuboctahedra, corners with fourteen AcCs4Ac8 cuboctahedra, edges with six equivalent CsAc12 cuboctahedra, edges with twelve AcCs4Ac8 cuboctahedra, faces with four equivalent CsAc12 cuboctahedra, and faces with sixteen AcCs4Ac8 cuboctahedra.
36 MATERIALS SCIENCE↗
Solar Dynamics Observatory Guidance, Navigation, and Control System Overview
The Solar Dynamics Observatory (SDO) was designed and built at the Goddard Space Flight Center, launched from Cape Canaveral on February 11, 2010, and reached its final geosynchronous science orbit on March 16, 2010. The purpose of SDO is to observe the Sun and continuously relay data to a dedicated ground station. SDO remains Sun-pointing throughout most of its mission for the instruments to take measurements of the Sun. The SDO attitude control system (ACS) is a single-fault tolerant design. Its fully redundant attitude sensor complement includes sixteen coarse Sun sensors (CSSs), a digital Sun sensor (DSS), three two-axis inertial reference units (IRUs), and two star trackers (STs). The ACS also makes use of the four guide telescopes included as a part of one of the science instruments. Attitude actuation is performed using four reaction wheels assemblies (RWAs) and eight thrusters, with a single main engine used to provide velocity-change thrust for orbit raising. The attitude control software has five nominal control modes, three wheel-based modes and two thruster-based modes. A wheel-based Safehold running in the attitude control electronics box improves the robustness of the system as a whole. All six modes are designed on the same basic proportional-integral-derivative attitude error structure, with more robust modes setting their integral gains to zero. This paper details the final overall design of the SDO guidance, navigation, and control (GN&C) system and how it was used in practice during SDO launch, commissioning, and nominal operations. This overview will include the ACS control modes, attitude determination and sensor calibration, the high gain antenna (HGA) calibration, and jitter mitigation operation. The Solar Dynamics Observatory mission is part of the NASA Living With a Star program, which seeks to understand the changing Sun and its effects on the Solar System, life, and society. To this end, the SDO spacecraft carries three Sun-observing instruments: Helioseismic and Magnetic Imager (HMI), led by Stanford University; Atmospheric Imaging Assembly (AIA), led by Lockheed Martin Space and Astrophysics Laboratory; and Extreme Ultraviolet Variability Experiment (EVE), led by the University of Colorado. The basic mission is to observe the Sun for a very high percentage of the 5-year mission (10-year goal) with long stretches of uninterrupted observations and with constant, high-data-rate transmission to a dedicated ground station to be located in White Sands, New Mexico. These goals guided the design of the spacecraft bus that will carry and service the three-instrument payload. Overarching design goals for the bus are geosynchronous orbit, near-constant Sun observations with the ability to fly through eclipses, and constant HGA contact with the dedicated ground station. A three-axis stabilized ACS is needed both to point at the Sun accurately and to keep the roll about the Sun vector correctly positioned with respect to the solar north pole. This roll control is especially important for the magnetic field imaging of HM I. The mission requirements have several general impacts on the ACS design. Both the AIA and HMI instruments are very sensitive to the blurring caused by jitter. Each has an image stabilization system (ISS) with some ability to filter out high frequency motion, but below the bandwidth of the ISS the control system must compensate for disturbances within the ACS bandwidth or avoid exciting jitter at higher frequencies. Within the ACS bandwidth, the control requirement imposed by AIA is to place the center of the solar disk no more than 2 arc sec, 3 , from a body-defined target based on one of the GTs that accompany the instrument. This body-defined target, called the science reference boresight (SRB), was determined from the postlaunch orientation of the GTs by averaging the bounding telescope boresights for pitch to get a pitch SRB coordinate, and by averaging the bounding boresights for yaw toet the yaw SRB coordinate. The location of this SRB in the 0.5-deg field-of-view for each GT then becomes the central target for each telescope; one GT is selected for use as the ACS controlling guide telescope (CGT) at any given time. Fine Sun-pointing is effected based on this SRB for all three instruments when the Sun is within the linear range of the CGT. In addition to limiting jitter, HMI science requires averaging several observations, making the instrument sensitive to low frequency motion that induces differential motion between each observation. This requires the spacecraft attitude to be stable about the roll axis to approximately 10 arcsec over a ten-minute period. Instrument calibrations require that the spacecraft point the SRB up to 2.5 degrees in pitch and yaw away from the center of the Sun, placing the Sun outside the field-of-view of the guide telescopes. In such instances, when the GTs cannot provide the definitive target for the ACS, on-board attitude determination combined with ephemeris prediction of the Sun direction must provide the definitive target. EVE is capable of observing the Sun with less dependence on attitude control. However, the ground data processing needs for calibrations result in the most strict attitude knowledge requirements for the mission: [35,70,70] arcsec, 3 , of knowledge with respect to the center of the solar disk. In addition to driving the ACS sensor selection, the knowledge requirements, which have their effect primarily during Inertial mode calibrations, drive the accuracy requirements for the solar ephemeris. The need to achieve and maintain geosynchronous orbit (GEO) drove the need for high-efficiency propulsive systems and appropriate attitude control. The main engine provided high specific impulse for the maneuvers to attain GEO, while the smaller ACS thrusters managed the disturbance torques of the larger engine and provided the capability for much smaller adjustment burns on orbit. SDO s large solar profile means that solar radiation pressure is a large torque disturbance, and the momentum buildup from this disturbance and the GEO altitude drives the ACS to use thrusters to manage vehicle momentum. The demanding data capture budget for the mission, however, requires SDO to avoid frequent thruster maneuvers, while concerns about on-orbit jitter restrict the maximum desired wheel speeds desired from the RWAs. The plan for on-orbit wheel speed and momentum management will be discussed as well as what is now being done in operation after the jitter environment was characterized. The SDO ACS hardware complement is single-fault tolerant. Two main processors carry virtually identical copies of the command and data handling and ACS software, and two identical attitude control electronics (ACE) boxes carry Coldfire processors with contingency ACS software and other hardware interface cards; the ACE structure allows reaction wheels to be commanded by the Sun-pointing Safehold independent of the Mil Std 1553 data bus. The sixteen Adcole CSSs are grouped into primary and backup sets of eight sensors, each set providing the ability to calculate a sun vector. Each set of eight eyes provides full 4 -steradian coverage. The Adcole DSS comprises an optics head and a separate electronics box providing a 1553 data interface. The electronics box is mounted inside the Faraday cage created by the spacecraft bus module. The DSS head with its 32- deg square FOV is mounted on the instrument module with its boresight along the spacecraft X axis, nearly aligned with the Sun during observations. Adcole has designed the DSS calibration parameters so that the accuracy is 0.24 arcminutes within 10 deg of the boresight, and diminishes to 3 arcminutes as the Sun moves towards the edges of its FOV . This DSS calibration scheme provides higher accuracy attitude determination over the range of the instrument calibration maneuvers.
Morgenstern, Wendy M.↗
Materials Data on SrAc3 by Materials Project
SrAc3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Sr is bonded to twelve Ac atoms to form SrAc12 cuboctahedra that share corners with six equivalent SrAc12 cuboctahedra, corners with twelve AcSr4Ac8 cuboctahedra, edges with eighteen AcSr4Ac8 cuboctahedra, faces with eight equivalent SrAc12 cuboctahedra, and faces with twelve AcSr4Ac8 cuboctahedra. There are six shorter (4.05 Å) and six longer (4.07 Å) Sr–Ac bond lengths. There are three inequivalent Ac sites. In the first Ac site, Ac is bonded to four equivalent Sr and eight Ac atoms to form AcSr4Ac8 cuboctahedra that share corners with four equivalent SrAc12 cuboctahedra, corners with fourteen AcSr4Ac8 cuboctahedra, edges with six equivalent SrAc12 cuboctahedra, edges with twelve AcSr4Ac8 cuboctahedra, faces with four equivalent SrAc12 cuboctahedra, and faces with sixteen AcSr4Ac8 cuboctahedra. There are six shorter (4.01 Å) and two longer (4.14 Å) Ac–Ac bond lengths. In the second Ac site, Ac is bonded to four equivalent Sr and eight equivalent Ac atoms to form AcSr4Ac8 cuboctahedra that share corners with four equivalent SrAc12 cuboctahedra, corners with fourteen AcSr4Ac8 cuboctahedra, edges with six equivalent SrAc12 cuboctahedra, edges with twelve equivalent AcSr4Ac8 cuboctahedra, faces with four equivalent SrAc12 cuboctahedra, and faces with sixteen AcSr4Ac8 cuboctahedra. In the third Ac site, Ac is bonded to four equivalent Sr and eight equivalent Ac atoms to form AcSr4Ac8 cuboctahedra that share corners with four equivalent SrAc12 cuboctahedra, corners with fourteen AcSr4Ac8 cuboctahedra, edges with six equivalent SrAc12 cuboctahedra, edges with twelve equivalent AcSr4Ac8 cuboctahedra, faces with four equivalent SrAc12 cuboctahedra, and faces with sixteen AcSr4Ac8 cuboctahedra.
36 MATERIALS SCIENCE↗
Development of 225Ac-doped biocompatible nanoparticles for targeted alpha therapy
Abstract Targeted alpha therapy (TAT) relies on chemical affinity or active targeting using radioimmunoconjugates as strategies to deliver α-emitting radionuclides to cancerous tissue. These strategies can be affected by transmetalation of the parent radionuclide by competing ions in vivo and the bond-breaking recoil energy of decay daughters. The retention of α-emitting radionuclides and the dose delivered to cancer cells are influenced by these processes. Encapsulating α-emitting radionuclides within nanoparticles can help overcome many of these challenges. Poly(lactic- co -glycolic acid) (PLGA) nanoparticles are a biodegradable and biocompatible delivery platform that has been used for drug delivery. In this study, PLGA nanoparticles are utilized for encapsulation and retention of actinium-225 ([ 225 Ac]Ac 3+ ). Encapsulation of [ 225 Ac]Ac 3+ within PLGA nanoparticles (Z ave = 155.3 nm) was achieved by adapting a double-emulsion solvent evaporation method. The encapsulation efficiency was affected by both the solvent conditions and the chelation of [ 225 Ac]Ac 3+ . Chelation of [ 225 Ac]Ac 3+ to a lipophilic 2,9-bis-lactam-1,10-phenanthroline ligand ([ 225 Ac]AcBLPhen) significantly decreased its release (< 2%) and that of its decay daughters (< 50%) from PLGA nanoparticles. PLGA nanoparticles encapsulating [ 225 Ac]AcBLPhen significantly increased the delivery of [ 225 Ac]Ac 3+ to murine (E0771) and human (MCF-7 and MDA-MB-231) breast cancer cells with a concomitant increase in cell death over free [ 225 Ac]Ac 3+ in solution. These results demonstrate that PLGA nanoparticles have potential as radionuclide delivery platforms for TAT to advance precision radiotherapy for cancer. In addition, this technology offers an alternative use for ligands with poor aqueous solubility, low stability, or low affinity, allowing them to be repurposed for TAT by encapsulation within PLGA nanoparticles. Graphical Abstract
60 APPLIED LIFE SCIENCES↗
Autonomous System Inference, Trojan, and Adversarial Reprogramming Attack and Defense (Final)
In the world of ever-advancing technology, Autonomous Systems (AS) find extensive application, bolstering functionalities of critical infrastructures such as nuclear power plants. These systems, however, are increasingly becoming a target for nefarious activities, namely through inference attacks, trojan attacks, and adversarial reprogramming. This paper delves into a comprehensive exploration of machine learning (ML)-driven autonomous control systems within advanced nuclear reactor designs, revealing the vulnerabilities and proposing strategies for defense against potential cyber-attacks. Advanced cyber-attacks against critical infrastructure and the energy sector are becoming more common. With the invention of autonomous control systems (ACS) within advanced nuclear reactor designs, system designers, reactor operators, and regulators must consider cybersecurity during the design and operational phases. This article provides a cyber threat assessment of machine learning (ML)- based digital twinning (DT) technologies in the context of advanced reactor ACS. A cyber-physical testbed was created to emulate nuclear reactor digital instrumentation and controls (I&C) and act as a basis for the ACS. The ACS was designed as two plant-level DTs predicting reactor malfunctions and determining control actions and two component-level DTs responsible for classifying component states and forecasting component inputs and outputs (I/O). Two duplicate ACS designs– one using a traditional ML framework and one using an automated ML (AutoML) framework– were created and tested against cyber-attacks on training data, real-time process data, and ML model architectures to determine their respective qualitative cyber-risk in terms of likelihood and impact. Both frameworks showed similar cyber-resilience against training, real-time, and ML architecture attacks, proving that neither is inherently more secure. Recommended safeguard and security measures are posed to system designers, reactor operators, and regulators to maintain the cybersecurity of ML-based DT technologies such as ACS, prompting a holistic view of shared responsibility for maintaining cyber-secure ML-based systems. As global reliance on generation III reactors begins to be critically assessed, the evolution towards advanced reactor systems utilizing digital instrumentation and controls (I&C) becomes not merely preferable, but essential. The integration of semi and fully autonomous control systems (ACS), powered by digital I&C and machine learning (ML)-based digital twinning (DT) technologies, emerges as a potent strategy to mitigate operations and maintenance costs, thereby enhancing the economic feasibility of novel reactor designs. However, with a staggering 500% and 380% increase in cyber-attacks reported against the energy sector by the United States Department of Energy (DoE) and the European Union respectively, a surge in cyber vulnerabilities specifically targeting the nuclear industry has been 2 markedly observed. Notable incidents, such as the W32.Ramnit spyware infiltration at the Gundremmingen nuclear power plant in Germany and the Dtrack spyware intrusion at the Kudankulam nuclear power plant in India, while not directly compromising core industrial control systems (ICS), underscore a compelling necessity to fortify cybersecurity protocols in safeguarding reactor systems against increasingly adept digital adversaries. In light of this, our investigation extends beyond conventional cybersecurity parameters, diving into the intricate web of potential vulnerabilities woven into ML-based DTs and ACS in advanced reactor systems. A crafted cyber-physical testbed and preliminary ACS were devised to act as a mirror, reflecting potential configurations of advanced reactor control designs. Moreover, this study is intertwined with a scrutinization of ML models, developed either through conventional, manually tuned methodologies or via automated means through AutoML, probing into their cyber-risk profiles within operational technology (OT) environments. Expanding on this, two distinct ACS blueprints were forged – one navigating through the corridors of traditional ML and the other traversing the path of AutoML – in an effort to holistically encapsulate the considerations pivotal to ML-based DT control system design. Employing the SANS Institute Industrial Control System (ICS) Kill Chain and the MITRE ATT&CK Tactics, Techniques, and Procedures (TTP) framework, a structured analysis was conducted, launching three targeted attacks against the training dataset, real-time dataset, and ML models, therein dissecting the potential cyber-attack implications against both ML frameworks within an ACS milieu. It is essential to note that three distinct categories of attacks were conducted against both ACS configurations, each encompassing three distinct ML-based DTs, cumulating in a total of 18 varied attacks. This exploration extends into the realms of Autonomous System Inference, Trojan, and Adversarial Reprogramming Attack and Defense, unraveling vulnerabilities, and opportunities for fortified defenses against such intrusions, particularly where ML-driven technologies, and by extension, ACS, are deployed. Final recommendations, articulated through a lens of security, safeguard, and implementation considerations, are presented for both traditional and AutoML models, anchoring upon the existing knowledge landscape and ML-based DT modeling for ACS, and are offered as a beacon to guide the nuclear industry through the intricate cybersecurity challenges that lie ahead.
22 GENERAL STUDIES OF NUCLEAR REACTORS↗
Materials Data on SrAc3 by Materials Project
SrAc3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr is bonded to twelve Ac atoms to form SrAc12 cuboctahedra that share corners with four equivalent SrAc12 cuboctahedra, corners with eight equivalent AcSr4Ac8 cuboctahedra, edges with eight equivalent SrAc12 cuboctahedra, edges with sixteen equivalent AcSr4Ac8 cuboctahedra, faces with four equivalent SrAc12 cuboctahedra, and faces with fourteen AcSr4Ac8 cuboctahedra. There are eight shorter (4.04 Å) and four longer (4.06 Å) Sr–Ac bond lengths. There are two inequivalent Ac sites. In the first Ac site, Ac is bonded to four equivalent Sr and eight equivalent Ac atoms to form AcSr4Ac8 cuboctahedra that share corners with four equivalent AcSr4Ac8 cuboctahedra, corners with eight equivalent SrAc12 cuboctahedra, edges with twenty-four AcSr4Ac8 cuboctahedra, faces with six equivalent SrAc12 cuboctahedra, and faces with twelve AcSr4Ac8 cuboctahedra. All Ac–Ac bond lengths are 4.04 Å. In the second Ac site, Ac is bonded to four equivalent Sr and eight Ac atoms to form AcSr4Ac8 cuboctahedra that share corners with twelve equivalent AcSr4Ac8 cuboctahedra, edges with eight equivalent SrAc12 cuboctahedra, edges with sixteen AcSr4Ac8 cuboctahedra, faces with four equivalent SrAc12 cuboctahedra, and faces with fourteen AcSr4Ac8 cuboctahedra. All Ac–Ac bond lengths are 4.06 Å.
36 MATERIALS SCIENCE↗
Materials Data on Ac3Dy by Materials Project
Ac3Dy is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ac sites. In the first Ac site, Ac is bonded to eight Ac and four equivalent Dy atoms to form AcAc8Dy4 cuboctahedra that share corners with twelve equivalent AcAc8Dy4 cuboctahedra, edges with eight equivalent DyAc12 cuboctahedra, edges with sixteen AcAc8Dy4 cuboctahedra, faces with four equivalent DyAc12 cuboctahedra, and faces with fourteen AcAc8Dy4 cuboctahedra. There are four shorter (3.89 Å) and four longer (3.90 Å) Ac–Ac bond lengths. All Ac–Dy bond lengths are 3.89 Å. In the second Ac site, Ac is bonded to eight equivalent Ac and four equivalent Dy atoms to form AcAc8Dy4 cuboctahedra that share corners with four equivalent AcAc8Dy4 cuboctahedra, corners with eight equivalent DyAc12 cuboctahedra, edges with twenty-four AcAc8Dy4 cuboctahedra, faces with six equivalent DyAc12 cuboctahedra, and faces with twelve AcAc8Dy4 cuboctahedra. All Ac–Dy bond lengths are 3.90 Å. Dy is bonded to twelve Ac atoms to form DyAc12 cuboctahedra that share corners with four equivalent DyAc12 cuboctahedra, corners with eight equivalent AcAc8Dy4 cuboctahedra, edges with eight equivalent DyAc12 cuboctahedra, edges with sixteen equivalent AcAc8Dy4 cuboctahedra, faces with four equivalent DyAc12 cuboctahedra, and faces with fourteen AcAc8Dy4 cuboctahedra.
36 MATERIALS SCIENCE↗
Materials Data on Ac3Ce by Materials Project
Ac3Ce is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ac sites. In the first Ac site, Ac is bonded to eight Ac and four equivalent Ce atoms to form AcAc8Ce4 cuboctahedra that share corners with twelve equivalent AcAc8Ce4 cuboctahedra, edges with eight equivalent CeAc12 cuboctahedra, edges with sixteen AcAc8Ce4 cuboctahedra, faces with four equivalent CeAc12 cuboctahedra, and faces with fourteen AcAc8Ce4 cuboctahedra. There are four shorter (3.73 Å) and four longer (3.74 Å) Ac–Ac bond lengths. All Ac–Ce bond lengths are 3.73 Å. In the second Ac site, Ac is bonded to eight equivalent Ac and four equivalent Ce atoms to form AcAc8Ce4 cuboctahedra that share corners with four equivalent AcAc8Ce4 cuboctahedra, corners with eight equivalent CeAc12 cuboctahedra, edges with twenty-four AcAc8Ce4 cuboctahedra, faces with six equivalent CeAc12 cuboctahedra, and faces with twelve AcAc8Ce4 cuboctahedra. All Ac–Ce bond lengths are 3.74 Å. Ce is bonded to twelve Ac atoms to form CeAc12 cuboctahedra that share corners with four equivalent CeAc12 cuboctahedra, corners with eight equivalent AcAc8Ce4 cuboctahedra, edges with eight equivalent CeAc12 cuboctahedra, edges with sixteen equivalent AcAc8Ce4 cuboctahedra, faces with four equivalent CeAc12 cuboctahedra, and faces with fourteen AcAc8Ce4 cuboctahedra.
36 MATERIALS SCIENCE↗