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Thermal Evaluation of CCS and NACS Reference Devices and Adapters
It is important for manufacturers of electric vehicle charging connectors, inlets, and adapters to understand the thermal performance of their devices. Various standards, such as SAE J1772, SAE J3400, IEC 62196, UL 2251, and UL 2252, list temperature limits that charging hardware needs to meet. However, there are currently very limited standardized reference devices against which to measure connector performance, and those that do currently exist generally serve charging currents less than 500A. This can make determining whether a charging connector meets the appropriate temperature limits difficult. Additionally, as automakers and charging station suppliers transition from the SAE J1772 CCS charging standard to SAE J3400 NACS, a number of CCS-to-NACS and NACS-to-CCS adapters are entering the market. These devices are being produced both by well-known automakers/equipment OEMs and lesser-known third-party suppliers, across a wide range of price points and construction qualities. Though SAE J3400/1 and UL 2252 lay out standards for adapter construction, performance and overtemperature response, there is no guarantee that any particular adapter will follow these standards and react to overtemperature events appropriately. This work addresses these issues by developing and evaluating a set of CCS and NACS reference inlet devices to validate the performance of charging connectors in the 500-800A range. The work also evaluates the performance of multiple NACS-to-CCS and CCS-to-NACS charging adapters with respect to UL 2252 temperature limits and SAE J3400/1 overtemperature signaling criteria.
A Strategy for NACS investment in Machine Learning
The Nuclear and Chemical Sciences (NACS) Division furnishes the expertise in the scientific areas of chemical, nuclear and isotopic sciences that are foundational in the Laboratory’s national security missions. This expertise is maintained and advanced through identification, development and application of state-of-the-art theoretical, computational and experimental methods and tools. Recent developments in artificial intelligence and machine learning (AI/ML) techniques enabled by advances in computing capabilities and widespread availability of powerful software implementations have made use of these techniques ubiquitous across both science and industry. While the scope of AI/ML applications is incredibly large and evolves very rapidly, the topics most relevant to NACS missions fall into the general category of detecting, categorizing or identifying features in large, complex datasets using either supervised or unsupervised learning. This covers both basic scientific data analysis and the development of efficient surrogate models of real-life technological systems, experimental detectors, or theoretical models. To remain at the forefront of its core scientific disciplines, NACS must both cultivate ML expertise as well as continuously explore applying this expertise to new problems or utilizing new methods. This document identifies the key areas where this support is critical and provides a strategy for investing in them.
Benchmarking MELCOR's NAC Package to ABCOVE Tests AB5 and AB6
This report presents analyses of the AB5 and AB6 ABCOVE sodium spray fire experiments with the MELCOR code. This code simulates the progression of accident events for analysis and auditing purposes of nuclear facilities during accident conditions. Historically, the ABCOVE experiments have contributed to the validation of aerosol physics and related phenomena. Given advancements in sodium-cooled reactor designs, characterization of the sodium spray combustion may further the review and validation of newly incorporated sodium properties and physics packages, namely, the sodium equations of state (EOS) and the sodium combustion (NAC) package within MELCOR. By analyzing the AB5 and AB6 experiments with and without the NAC package, sodium specificity for spray combustion and aerosol formation as well as speciation of the combustion products are reviewed with the new packages. This effort provides code users with a demonstration of the current code capabilities. This report provides the current best practices for the NAC package as well as a discussion of any issues observed while performing the presented analyses.
The NAC LWT for Research Reactor Spent Fuel Shipments - 20126
The NAC Legal Weight Truck (LWT) Cask is a Type B(U)F-96 transportation package originally designed for shipment of PWR and BWR spent fuel assemblies. Its versatile design provides maximum flexibility and cost-efficiency to support shipment of a wide range of spent fuel. This cask has been used for research reactor fuel shipments in over a dozen countries and counting. It has supported multiple domestic research reactor spent fuel shipments. These contents are licensed by the U.S. NRC and have been validated for use around the world. These shipments need the capability to be loaded and unloaded in a pool, in a dry facility or in a parking lot. In this paper, the analysis, design changes and operations to meet these specific content challenges will be presented. The paper provides a technical overview of the NAC LWT and identifies the design features and technology advancements making the NAC LWT readily adaptable and flexible solution for packaging research reactor spent fuel. (authors)
Benchmarking MELCOR's NAC Package to ABCOVE Test AB7
This report presents analyses of the AB7 ABCOVE sodium spray fire experiment with the MELCOR code. This code simulates the progression of accident events for analysis and auditing purposes of nuclear facilities during accident conditions. Historically, the ABCOVE experiments have contributed to the validation of aerosol physics and related phenomena. Given advancements in sodium-cooled reactor designs, characterization of the sodium spray combustion may further the review and validation of newly incorporated sodium properties and physics packages, namely, the sodium equations of state (EOS) and the sodium combustion (NAC) package within MELCOR. Previously, the AB5 and AB6 experiments were analyzed with and without the NAC package. This work builds on the previous analyses with a demonstration of the current code capabilities of MELCOR with a more mild Na spray and pool fire scenario.
Time Log of the Unloading of an NAC-LWT Cask from a Semi at Oak Ridge National Laboratory in 2016
On Jan 21, 2016, a NAC LWT was unloaded at ORNL. This is a firsthand, moment by moment time record of the movements necessary for unloading (NAC-LWT SARP). This is a legal weight truck cask, conveyed within a shipping container that can be disassembled.
Biomass formation and sugar release efficiency of Populus modified by altered expression of a NAC transcription factor
Woody biomass is an important feedstock for biofuel production. Manipulation of wood properties that enable efficient conversion of biomass to biofuel reduces cost of biofuel production. Wood cell wall composition is regulated at several levels that involve expression of transcription factors such as wood-/secondary cell wall-associated NAC domains (WND or SND). In Arabidopsis thaliana, SND1 regulates cell wall composition through activation of its down-stream targets such as MYBs. The functional aspects of SND1 homologs in the woody Populus have been studied through transgenic manipulation. In this study, we investigated the role of PdWND1B, Populus SND1 sequence ortholog, in wood formation using transgenic manipulation through over-expression or silencing under the control of a vascular-specific 4-coumarate-CoA ligase (4CL) promoter. As compared with control plants, PdWND1B-RNAi plants were shorter in height, with significantly reduced stem diameter and dry biomass, whereas there were no significant differences in growth and productivity of PdWND1B over-expression plants. Conversely, PdWND1B over-expression lines showed a significant reduction in cellulose and increase in lignin content, whereas there was no significant impact on lignin content of downregulated lines. Stem carbohydrate composition analysis revealed a decrease in glucose, mannose, arabinose, and galactose, but an increase in xylose in the over-expression lines. Transcriptome analysis revealed upregulation of several downstream transcription factors and secondary cell wall related structural genes in the PdWND1B over-expression lines, partly explaining the observed phenotypic changes in cell wall chemistry. Relative to the control, glucose release efficiency and ethanol production from stem biomass was significantly reduced in over-expression lines. Our results show that PdWND1B is an important factor determining biomass productivity, cell wall chemistry and its conversion to biofuels in Populus.
Materials Data on NaC by Materials Project
NaC crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Na is bonded in a 2-coordinate geometry to six equivalent C atoms. There are two shorter (2.61 Å) and four longer (2.72 Å) Na–C bond lengths. C is bonded in a 7-coordinate geometry to six equivalent Na and one C atom. The C–C bond length is 1.26 Å.
Materials Data on NaC by Materials Project
NaC crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. Na is bonded in a 6-coordinate geometry to six equivalent C atoms. There are a spread of Na–C bond distances ranging from 2.61–2.79 Å. C is bonded in a 7-coordinate geometry to six equivalent Na and one C atom. The C–C bond length is 1.26 Å.
Materials Data on NaCS(OF)3 by Materials Project
NaCF3SO3 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of eight fluoroform molecules and one SO3Na sheet oriented in the (0, 0, 1) direction. In the SO3Na sheet, there are eight inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.41–2.93 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.36–2.80 Å. In the third Na1+ site, Na1+ is bonded in a square pyramidal geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.33–2.54 Å. In the fourth Na1+ site, Na1+ is bonded in a distorted square pyramidal geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.33–2.63 Å. In the fifth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.33–2.78 Å. In the sixth Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.42–2.76 Å. In the seventh Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.43–2.96 Å. In the eighth Na1+ site, Na1+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.35–2.56 Å. There are eight inequivalent S4+ sites. In the first S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of S–O bond distances ranging from 1.45–1.48 Å. In the second S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.46 Å) and two longer (1.47 Å) S–O bond length. In the third S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.46 Å) and one longer (1.47 Å) S–O bond length. In the fourth S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of S–O bond distances ranging from 1.45–1.48 Å. In the fifth S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.45 Å) and two longer (1.47 Å) S–O bond length. In the sixth S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.46 Å) and one longer (1.47 Å) S–O bond length. In the seventh S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.46 Å) and one longer (1.48 Å) S–O bond length. In the eighth S4+ site, S4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.46 Å) and one longer (1.47 Å) S–O bond length. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+ and one S4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one S4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to two Na1+ and one S4+ atom. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to one Na1+ and one S4+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one S4+ atom. In the eleventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Na1+ and one S4+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+ and one S4+ atom. In the fourteenth O2- site, O2- is bonded in a bent 120 degrees geometry to one Na1+ and one S4+ atom. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one S4+ atom. In the sixteenth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the seventeenth O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+ and one S4+ atom. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one S4+ atom. In the nineteenth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the twentieth O2- site, O2- is bonded in a distorted T-shaped geometry to two Na1+ and one S4+ atom. In the twenty-first O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom. In the twenty-second O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one S4+ atom. In the twenty-third O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+ and one S4+ atom. In the twenty-fourth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one S4+ atom.
NACS 2022 FRIB Investment Strategy
The Facility for Rare Isotope Beams (FRIB) that will begin operations later this year will vastly increase the number of unstable isotopes available for experiments that, together with new theoretical developments will expand our understanding of nuclear structure and nuclear reactions that produce the elements of the periodic table and power the cosmos. The knowledge and understanding gained from FRIB will benefit a variety of applications including stockpile science, nuclear forensics, nonproliferation, nuclear energy, and nuclear medicine. LLNL is actively involved in a variety of basic and applied science activities related to FRIB. These activities are listed below and documented in the following sections: 1. FRIB Decay Station, 2. Isotope Harvesting, 3. Direct Reactions, 4. Surrogate Reactions, 5. Nuclear Structure and Collectivity, 6. Nuclear Fission, and 7. Nuclear Theory.
Thermal Evaluation of CCS and NACS Reference Devices and Adapters
A review of NLR's work in charging system reliability for charging inlets, connectors, and adapters. The review includes a detailed discussion on (a) the development of a reference device for the thermal performance of charging connectors and adapters, (b) evaluation of charging adapters and their thermal warning and shutdown response, (c) implications of side-load from real-world implementations, and (d) strengthening the conformance evaluation for end caps based on field data.
XND1 Regulates Secondary Wall Deposition in Xylem Vessels through the Inhibition of VND Functions
Secondary wall deposition in xylem vessels is activated by Vascular-Related NAC Domain proteins (VNDs) that belong to a group of secondary wall NAC (SWN) transcription factors. By contrast, Xylem NAC Domain1 (XND1) negatively regulates secondary wall deposition in xylem vessels when overexpressed. The mechanism by which XND1 exerts its functions remains elusive. We employed the promoter of the fiber-specific Secondary Wall-Associated NAC Domain1 (SND1) gene to ectopically express XND1 in fiber cells to investigate its mechanism of action on secondary wall deposition. Ectopic expression of XND1 in fiber cells severely diminished their secondary wall deposition and drastically reduced the expression of SWN-regulated downstream transcription factors and secondary wall biosynthetic genes but not that of the SWN genes themselves. Transactivation analyses revealed that XND1 specifically inhibited SWN-activated expression of these downstream genes but not their MYB46-activated expression. Both the NAC domain and the C-terminus of XND1 were required for its inhibitory function and its NAC domain interacted with the DNA-binding domains of SWNs. XND1 was shown to be localized in the cytoplasm and the nucleus and its co-expression with VND6 resulted in the cytoplasmic sequestration of VND6. Furthermore, the C-terminus of XND1 was indispensable for the XND1-mediated cytoplasmic retention of VND6 and its fusion to VND6 was able to direct VND6 to the cytoplasm and render it unable to activate the gene expression. Since the XND1 gene is specifically expressed in xylem cells, these results indicate that XND1 acts through inhibiting VND functions to negatively regulate secondary wall deposition in xylem vessels.
Analytical nonadiabatic coupling and state-specific energy gradient for the crystal field Hamiltonian describing lanthanide single-ion magnets
Paramagnetic molecules with a metal ion as an electron spin center are promising building blocks for molecular qubits and high-density memory arrays. However, fast spin relaxation and decoherence in these molecules lead to a rapid loss of magnetization and quantum information. Nonadiabatic coupling (NAC), closely related to spin-vibrational coupling, is the main source of spin relaxation and decoherence in paramagnetic molecules at higher temperatures. Predicting these couplings using numerical differentiation requires a large number of computationally intensive ab initio or crystal field electronic structure calculations. To reduce computational cost and improve accuracy, we derive and implement analytical NAC and state-specific energy gradient for the ab initio parametrized crystal field Hamiltonian describing single-ion molecular magnets. Our implementation requires only a single crystal field calculation. In addition, the accurate NACs and state-specific energy gradients can be used to model spin relaxation using sophisticated nonadiabatic molecular dynamics, which avoids the harmonic approximation for molecular vibrations. To test our implementation, we calculate the NAC values for three lanthanide complexes. Finally, the predicted values support the relaxation mechanisms reported in previous studies.
Nuclear and Chemical Sciences Division: Investment Strategy 2023
The mission of the Nuclear and Chemical Sciences (NACS) Division within the Physical and Life Sciences (PLS) Directorate is to advance scientific understanding, capabilities, and technologies in nuclear and particle physics, radiochemistry, forensic science, and isotope systems to support LLNL’s national security mission. NACS Division personnel conduct a diverse range of research activities in particle physics, nuclear physics, radiation detection, nuclear measurements, chemical and nuclear forensic science, nuclear and radiochemistry, isotope geochemistry, and environmental science. These areas are leveraged to address evolving national security challenges. Scientific research provides the foundation for addressing these challenges, and it is also the principal means of attracting, training, and retaining staff scientists who can deliver solutions across the Laboratory’s mission space. The overarching strategy is to position the NACS Division at the nexus between fundamental nuclear and chemical science research and nuclear security applications. This approach will support efforts to recruit, train, and retain top-flight scientists and engineers who will play a key role in executing the Laboratory’s core nuclear security missions, while also enhancing LLNL’s reputation as a center for innovative scientific research. This document describes the strategic vision that will be used to guide key investments aimed at enabling NACS scientists to lead new efforts and meet future challenges.
Nuclear Forensics
Nuclear forensics is a key part of the nuclear security strategy for the United States and the international community. The NACS Division is central to the leadership role that LLNL has had in nuclear forensics over the past 25 years. Our current nuclear forensic program includes conducting R&D on provenance and attribution signatures, collaborating with international partners, training the next generation of nuclear forensic experts, developing test materials for verification and validation exercises, and providing expert advice to national and international policy makers. Key to our success in these areas has been the strong and continuing involvement in nuclear forensic casework obtained through law enforcement and intelligence channels as well as our outstanding analytical capabilities. NACS must continue to conduct forward-thinking R&D in nuclear forensics that supports operational programs and addresses intelligence gaps. To maintain leadership in nuclear forensics, we must attract, develop, and retain the best talent. The NNSA has a central leadership role in developing educational initiatives for nuclear forensics. In concert with the Glenn T. Seaborg Institute, the NACS Division will continue to participate in all nuclear forensic educational initiatives (undergraduate, graduate, postdoctoral) and incorporate LLNL’s D&I vision into its student and postdoc recruitment efforts. We will continue to build formal relationships with key academic partners and institutions with active and emerging nuclear forensic research interests. We will also strengthen relationships with NNSA DNN and SSAA funded university consortia (e.g. NSSC, ACE, CNEC, CVT, ETI, MTV), helping them conduct research of interest and relevance to nuclear forensics, while at the same time evaluating and recruiting promising talent from these programs.
Partial connectomes of labeled dopaminergic circuits reveal non-synaptic communication and axonal remodeling after exposure to cocaine
Dopaminergic (DA) neurons exert profound influences on behavior including addiction. However, how DA axons communicate with target neurons and how those communications change with drug exposure remains poorly understood. We leverage cell type-specific labeling with large volume serial electron microscopy to detail DA connections in the nucleus accumbens (NAc) of the mouse (Mus musculus) before and after exposure to cocaine. We find that individual DA axons contain different varicosity types based on their vesicle contents. Spatially ordering along individual axons further suggests that varicosity types are non-randomly organized. DA axon varicosities rarely make specific synapses (<2%, 6/410), but instead are more likely to form spinule-like structures (15%, 61/410) with neighboring neurons. Days after a brief exposure to cocaine, DA axons were extensively branched relative to controls, formed blind-ended ‘bulbs’ filled with mitochondria, and were surrounded by elaborated glia. Finally, mitochondrial lengths increased by ~2.2 times relative to control only in DA axons and NAc spiny dendrites after cocaine exposure. We conclude that DA axonal transmission is unlikely to be mediated via classical synapses in the NAc and that the major locus of anatomical plasticity of DA circuits after exposure to cocaine are large-scale axonal re-arrangements with correlated changes in mitochondria.