Evaluating the microstructure and origin of nonmetallic inclusions in as-cast U-10Mo fuel
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Kautz, Elizabeth J. (ORCID:0000000263389223)↗
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The Melting Behavior of Hydrogen Direct Reduced Iron in Molten Steel and Slag: An Integrated Computational and Experimental Study
Direct reduced iron (DRI) and hot briquetted iron (HBI) are essential feedstocks for tramp element control in the electric arc furnace (EAF). Due to greenhouse gas (GHG) concerns related to CO2 emissions, hydrogen as a substitute for natural gas and a reductant in DRI production is being widely explored to reduce GHG emissions in ironmaking. This study examines the melting behavior of hydrogen DRI (H-DRI) pellets in the EAF containing low-carbon (0.1 wt.%) molten steel and molten slag. A computational heat transfer model was developed to predict the melting behavior of H-DRI pellets. To validate the model, a set of experimental laboratory simulations was conducted by immersing H-DRI in a molten steel bath and slag. The temperature history at the center of the pellet during melting and the shell thickness at different melting stages were utilized to validate the model. The simulation results agree with the experimental measurements of steel balls and H-DRI in different metallic molten steel and slag baths.
Materials Science↗
Synthesis Methods for Nanoparticle Morphology Control in Energy Applications
Lightweight nano-composite materials, nano-coatings, nanocatalysts, nano-structured materials have demonstrated an ability to reduce emissions and maximize clean energy production. Nanoparticles play an important role in engineering and decarbonization for energy applications, and a wide range of nanoparticle synthesis methods have been developed to include those that enable control over particle morphology. The ability to control nanoparticle morphology allows the tailoring and improvement of material properties that will accelerate efforts towards lowering carbon emissions by developing advanced catalysts for carbon sequestration and will enhance energy efficient processes and technologies. Synthesis methods aimed towards shape control of nanoparticles have demonstrated an ability to form spheres, rods, flower-like shapes, cubes, plates, shells, and chiral geometries. Processing methods used to form these morphologies include microwave assisted synthesis, solvothermal, hydrothermal, and a wide range of capping agents. A discussion of a few of these methods is given along with results and applications.
36 MATERIALS SCIENCE↗
Solar Spectrum Conversion for an Algae Bioreactor (CRADA Final Report)
This project focused on developing advanced optical coatings to improve solar energy utilization. The research aimed to create lanthanide-doped upconversion nanoparticles (UCNPs) capable of capturing unused near-infrared (NIR) light from the sun and converting it into visible light (blue and red photons) that can be used for photosynthesis. The primary goal was to identify, synthesize, and integrate highly efficient UCNPs into a transparent thin-film device. Through a comprehensive workflow involving computer simulations, high-throughput robotic synthesis, and detailed optical characterization, the project successfully developed a high-performance material. The key technical achievement was the creation of a core-shell UCNP (NaYF₄:20%Yb³⁺, 2%Er³⁺ coated with a 10 nm NaYF₄ shell) that demonstrated a quantum yield of 3.2% for converting 980 nm NIR light into visible light. Transparent thin films fabricated from these nanoparticles showed excellent optical properties, confirming their potential for practical applications. This research adds to the scientific understanding of energy transfer in lanthanide materials and demonstrates a technically effective method for creating efficient light-converting coatings. The primary benefit to the public lies in the potential for these coatings to enhance the efficiency of solar-driven processes, such as boosting the growth of algae in photobioreactors for biofuel production.
14 SOLAR ENERGY↗
Structure of two-loop SMEFT anomalous dimensions via on-shell methods
We describe on-shell methods for computing one- and two-loop anomalous dimensions in the context of effective field theories containing higher-dimension operators. We also summarize methods for computing one-loop amplitudes, which are used as inputs to the computation of two-loop anomalous dimensions, and we explain how the structure of rational terms and judicious renormalization scheme choices can lead to additional vanishing terms in the anomalous dimension matrix at two loops. We describe the two-loop implications for the Standard Model Effective Field Theory (SMEFT). As a by-product of this analysis we verify a variety of one-loop SMEFT anomalous dimensions computed by Alonso, Jenkins, Manohar and Trott.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Multinucleon transfer in the interaction of 977 MeV and 1143 MeV Hg 204 with Pb 208
A previous study of symmetric collisions of massive nuclei has shown that current models of multinucleon transfer (MNT) reactions do not adequately describe the transfer product yields. To gain further insight into this problem, we have measured the yields of MNT products in the interaction of 977 (E/A = 4.79 MeV) and 1143 MeV (E/A = 5.60 MeV) 204 Hg with 208 Pb. We find that the yield of multinucleon transfer products are similar in these two reactions and are substantially lower than those observed in the reaction of 1257 MeV (E/A = 6.16 MeV) 204 Hg+ 198 Pt. We compare our measurements with the predictions of the GRAZING-F, dinuclear systems (DNS), and improved quantum molecular dynamics (ImQMD) models. We report that for the observed isotopes of the elements Au, Hg, Tl, Pb, and Bi, the measured values of the MNT cross sections are orders of magnitude larger than the predicted values. Furthermore, the various models predict the formation of nuclides near the N = 126 shell, which are not observed.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Operando NRIXS and XAFS Investigation of Segregation Phenomena in Fe-Cu and Fe-Ag Nanoparticle Catalysts during CO 2 Electroreduction
Operando nuclear resonant inelastic X-ray scattering (NRIXS) and X-ray absorption fine-structure spectroscopy (XAFS) measurements were used to gain insight into the structure and surface composition of FeCu and FeAg nanoparticles (NPs) during the electrochemical CO 2 reduction (CO 2 RR) and to extract correlations with their catalytic activity and selectivity. The formation of a core–shell structure during CO 2 RR for FeAg NPs was inferred from the analysis of the operando NRIXS data (phonon density of states, PDOS) and XAFS measurements. Electrochemical analysis of the FeAg NPs revealed a faradaic selectivity of 36 % for CO in 0.1 M KHCO 3 at -1.1 V vs. RHE, similar to that of pure Ag NPs. In contrast, a predominant selectivity towards H 2 evolution is obtained in the case of the FeCu NPs, analogous to the results obtained for pure Fe NPs, although small Cu NPs have also been shown to favor H 2 production.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
The Corrective Maintenance Paradigm Shift at Hanford's Tank Farms - 20077
Hanford's Tank Farms facilities have been used to safely store waste for over 70 years, with the first single-shell tanks being constructed in 1943. Tank Farm facilities consist of 149 single-shell tanks, 28 double-shell tanks, an evaporator facility, and wastewater treatment facilities. Tank Farm facilities are aging, with a tremendous corrective maintenance burden on the Tank Farm contractor. The mission of Tank Farm facilities is soon changing from waste storage to waste staging for the Hanford Waste Treatment and Immobilization Plant (WTP). WTP operations will demand a significant increase in Tank Farm facility operations, in which corrective maintenance outage windows will shrink drastically. This realization has forced the Tank Farm contractor to consider a paradigm shift in Tank Farm facilities Maintenance planning, and the use of reliability Engineering tools. The Tank Farm Production Operations Engineering Cognizant System Engineering (CSE) organization has led the way in motivating this paradigm shift. This shift has been realized through the use of: 1) technical exchange with other Department of Energy (DOE) contractors to develop improvements in the CSE program, 2) a shift from the use of lagging to leading system health indicators, and 3) a Plant Health Committee to unite Engineering, Operations, and Maintenance personnel toward a productive maintenance strategy. The CSE organization has held several technical exchanges with other DOE contractors to discuss CSE concepts, and how to better maintain aging infrastructure. The technical exchange with other contractors has greatly reduced the time required to make improvements in the Tank Farm CSE program. Other DOE contractors have already faced issues surrounding aging infrastructure, and have vast experience in improving the reliability and usable life of structures and components in nuclear facilities. The past CSE program used lagging health indicators to determine the health of systems. The key lagging indicator used to determine system health was availability, which is the percentage of time that a facility was ready for operation compared to the time the facility was demanded for operation. Availability was a good indicator of health in the waste storage mission of Tank Farms, where safe storage was the most important function of the facility, and where maintenance outage windows were typically long-duration. In current and future operations, outage windows are reducing, resulting in the need for much more reliable systems. Systems that have had high availability may suddenly become inoperable due to a failed component or sub-system. In several instances, the use of availability as an indicator of system health failed to predict system/equipment failure before its occurrence. In discussions with other DOE contractors, a set of reliability tools, including leading indicators of health, has been implemented in the CSE program. This primarily involves the use of failure modes and effects analysis and the study of equipment failure to develop system monitoring plans that focus on trending data to detect oncoming equipment failure ahead of time. In addition, the use of a Plant Health Committee has added significantly to the paradigm shift from a corrective maintenance philosophy to the use of predictive and preventive maintenance. The Plant Health Committee is a chartered team consisting of Engineering, Operations, and Maintenance personnel. CSEs use this forum to present the results of their performance monitoring, including the presentation of health via leading health indicators. The most positive aspect of this committee is the communication that it creates within these critical organizations. The Operations and Maintenance organization benefit from focusing maintenance on the reliability-centered focus provided by Engineering. Engineering benefits from the operational experience of the Operations organization and from the failure data that can be provided by Maintenance personnel. The continued use of the Plant Health Committee is expected to further decrease maintenance outage times, in better support of oncoming 24/7 operations. (authors)
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Mass transfer in catalytic depolymerization: External effectiveness factors and serendipitous processivity in stagnant and stirred melts
Several heterogeneous catalysts are being developed to recycle plastics. Most operate in viscous polymer melts, where external mass transfer effects could limit the supply of co-reactants to active sites. External mass transfer can also impede the diffusion of long chain products away from the catalyst after each cut. Product egress limitations could potentially confer unintentional processivity to catalyst operation, i.e. a tendency for the catalyst to repeatedly cut the same chain after an initial encounter. We formulate reaction–diffusion equations to quantify mass transfer effects on the co-reactant transport to the catalyst and the degree of serendipitous processivity. Results are developed for catalysts in stagnant or stirred melts, with simple expressions involving Damkohler, Peclet, and Sherwood numbers, i.e. dimensionless combinations of rate constants, catalyst particle size, polymer diffusivities, and shear rates (where applicable). In conclusion, we estimate the impact of these effects for a spherical core–shell catalyst.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Solvent Dynamics Are Critical to Understanding Carbon Dioxide Dissolution and Hydration in Water
Simulations of carbon dioxide (CO 2 ) in water may aid in understanding the impact of its accumulation in aquatic environments and help advance technologies for carbon capture and utilization (via, e.g., mineralization). Quantum mechanical (QM) simulations based on static molecular models with polarizable continuum solvation poorly reproduce the energetics of CO 2 hydration to form carbonic acid in water, independent of the level of QM theory employed. Only with density-functional-theory-based molecular dynamics and rare-event sampling, followed by energy corrections based on embedded correlated wavefunction theory (in conjunction with density functional embedding theory), can a close agreement between theory and experiment be achieved. Such multilevel simulations can serve as benchmarks for simpler, less costly models, giving insight into potential errors of the latter. The strong influence of sampling/averaging over dynamical solvent configurations on the energetics stems from the difference in polarity of both the transition state and product (both polar) versus the reactant (nonpolar). When a solute undergoes a change in polarity during reaction, affecting its interaction with the solvent, careful assessment of the energetic contribution of the solvent response to this change is critical. Here, we show that static models (without structural sampling) that incorporate three explicit water molecules can yield far superior results than models with more explicit water molecules because fewer water molecules yield less configurational artifacts. Static models intelligently incorporating both explicit (molecules directly participating in the reaction) and implicit solvation, along with a proper QM theory, e.g., CCSD(T) for closed-shell systems, can close the accuracy gap between static and dynamic models.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Chlorine and potassium enrichment in the Cassiopeia A supernova remnant
The elements in the Universe are synthesized primarily in stars and supernovae, where nuclear fusion favours the production of even-Z elements. In contrast, odd-Z elements are less abundant and their yields are highly dependent on detailed stellar physics, making theoretical predictions of their cosmic abundance uncertain. In particular, the origin of odd-Z elements such as phosphorus (P), chlorine (Cl) and potassium (K), which are important for planet formation and life, is poorly understood. While the abundances of these elements in Milky Way stars are close to solar values, supernova explosion models systematically underestimate their production by up to an order of magnitude, indicating that key mechanisms for odd-Z nucleosynthesis are currently missing from theoretical models. Here we report the observation of P, Cl and K in the Cassiopeia A supernova remnant using high-resolution X-ray spectroscopy with X-Ray Imaging and Spectroscopy Mission data, with the detection of K at above the 6σ level being the most significant finding. Supernova explosion models of normal massive stars cannot explain the element abundance pattern, especially the high abundances of Cl and K, while models that include stellar rotation, binary interactions or shell mergers agree closely with the observations. Our observations suggest that such stellar activity plays an important role in supplying these elements to the Universe.
Astronomy and AstroPhysics↗
Verification and Validation of Two Hydrodynamic Methods for Simulations of High Energy Density Physics Problems
A 3D verification and validation suite of test problems is presented and used to evaluate hydrodynamic methods within a radiation hydrodynamics code, xRAGE. These test problems exercise different levels of complexity, building towards ICF problems which in addition to hydrodynamics also include three temperature plasma physics, thermal conduction, and radiation diffusion. Among the problems in the test suite are the Kidder ball problem, the Verney shell problem, and a 5-material compression problem, which exercise different purely hydrodynamic methods implemented within xRAGE. There is excellent agreement between 2D and 3D XRAGE simulation results and between the xRAGE results and the benchmark solutions. Two 3D ICF test problems are also presented, based on an OMEGA direct drive capsule experiment and on a NIF indirect drive capsule experiment. It is demonstrated that the newer unsplit hydrodynamic method in xRAGE produces more vorticity relative to the older default method. For the indirect drive capsule, the 3D simulations are in reasonable agreement with the experimental values of ion temperature and neutron production.
47 OTHER INSTRUMENTATION↗
Modification of CO 2 /H 2 O selectivity of polymer for carbon capture materials
Today, the atmospheric carbon dioxide (CO 2 ) concentration is 421ppm, over one hundred ppm higher than it was at any point in the last 800,000 years (NASA, 2023). Multiple strategies are necessary to reduce the presence of carbon dioxide in the atmosphere. Besides limiting CO 2 output, carbon capture technology is essential to reduce the overall amount of CO 2 . The Microencapsulated CO 2 Sorbents (MECS) team at Lawrence Livermore National laboratory has developed technologies that can capture CO 2 inside microcapsules, where it can be temporarily stored and later released. In 2017, the commercial potential of these microcapsules was recognized. The brewing industry only requires about one third of the CO 2 it releases for carbonization and packaging, which Congwang Ye and Lionel Keene learned when they met with leaders of small breweries in Colorado to discuss employing carbon capture microcapsules in their processes to reduce their carbon footprint and production costs (Thomas, 2017). The breweries were interested in the technology, but the existing microcapsules require hydration, which is an expensive process for small brewers. In order to develop the microcapsules so they can be commercialized, it is essential to reduce their water loss to improve efficiency and reduce costs for the customers. One method to resolve this issue is to alter the membrane formulation by adding a material that is known to be hydrophobic to decrease the water permeability of the entire membrane. The goal of this project was to study the effect of dispersing a nanomaterial in the polymer membrane shells of microcapsules on the water vapor and carbon dioxide permeability of the membranes.
36 MATERIALS SCIENCE↗
Search for a new scalar decaying into new spin-1 bosons in four-lepton final states with the ATLAS detector
A search is conducted for a new scalar boson S, with a mass distinct from that of the Higgs boson, decaying promptly into four leptons ( ℓ = e , μ) via an intermediate state containing two on-shell, promptly decaying new spin-1 bosons Z d : S → Z d Z d → 4 ℓ , where the Z d boson has a mass between 15 and 300 GeV, and the S boson has a mass between either 30 and 115 GeV or 130 and 800 GeV. The search uses proton–proton collision data collected with the ATLAS detector at the Large Hadron Collider with an integrated luminosity of 139 fb−1 at a centre-of-mass energy of s = 13 TeV. No significant excess above the Standard Model background expectation is observed. Upper limits at 95% confidence level are set on the production cross-section times branching ratio, σ ( g g → S ) × B ( S → Z d Z d → 4 ℓ ) , as a function of the mass of both particles, m S and m Z d .
Aad, G↗
In-Situ Atomic-Scale Revelation of Amorphous Metallic Iron Formation during Hydrogen-Driven Reduction of Iron Oxides
The transition to hydrogen as a green reductant in metal production is critical for decarbonizing the metallurgical industry, yet atomic-scale mechanisms governing reduction pathways and phase evolution remain unresolved. Using in-situ environmental transmission electron microscopy, we identify a hidden pathway that reveals dynamic formation of amorphous metallic iron (Fe) during the hydrogen-driven reduction of ferrous oxides of Fe 3 O 4 and FeO. Real-time imaging uncovers three coexisting transformation routes: (i) Fe 3 O 4 → FeO, (ii) Fe 3 O 4 → amorphous Fe, and (iii) FeO → amorphous Fe. The resulting amorphous Fe exhibits fluid-like mobility, enabling its rapid aggregation and crystallization into core-shell nanostructures, with a crystalline core enveloped by an amorphous shell. Complementary ab initio molecular dynamics simulations trace the amorphous Fe formation to interfacial strain at the metal/oxide interfaces, where large lattice mismatches destabilize the metal lattice during initial metallization. This interplay between thermodynamics and kinetics governs phase evolution: thermodynamics favors a self-limiting amorphous Fe overlayer, while rapid oxide reduction kinetics drives amorphous overgrowth. Our findings demonstrate that amorphous intermediates bypass rate-limiting crystalline steps, providing mechanistic insights to optimize H 2 -based processes for sustainable steelmaking. In conclusion, these insights bridge the gap between macroscopic process engineering and atomic-scale dynamics, with broader implications for catalysis and nanostructured material synthesis, where oxide reduction pathways critically shape functional phases and microstructures.
36 MATERIALS SCIENCE↗
Search for a scalar partner of the top quark in the all-hadronic $t{\bar{t}}$ plus missing transverse momentum final state at $\sqrt{s}=13$ TeV with the ATLAS detector
A search for direct pair production of scalar partners of the top quark (top squarks or scalar third-generation up-type leptoquarks) in the all-hadronic $t{\bar{t}}$ plus missing transverse momentum final state is presented. The analysis of 139 $\hbox {fb}^{-1}$ of ${\sqrt{s}=13}$ TeV proton–proton collision data collected using the ATLAS detector at the LHC yields no significant excess over the Standard Model background expectation. To interpret the results, a supersymmetric model is used where the top squark decays via ${\tilde{t}} \rightarrow t^{(*)} {\tilde{\chi }}^0_1$ t ~ → t ( * ) χ ~ 1 0 , with $t^{(*)}$ t ( * ) denoting an on-shell (off-shell) top quark and ${\tilde{\chi }}^0_1$ χ ~ 1 0 the lightest neutralino. Three specific event selections are optimised for the following scenarios. In the scenario where $m_{{\tilde{t}}}> m_t+m_{{\tilde{\chi }}^0_1}$ m t ~ > m t + m χ ~ 1 0 , top squark masses are excluded in the range 400–1250 GeV for ${\tilde{\chi }}^0_1$ χ ~ 1 0 masses below 200 GeV at 95% confidence level. In the situation where $m_{{\tilde{t}}}\sim m_t+m_{{\tilde{\chi }}^0_1}$ m t ~ ~ m t + m χ ~ 1 0 , top squark masses in the range 300–630 GeV are excluded, while in the case where $m_{{\tilde{t}}}< m_W+m_b+m_{{\tilde{\chi }}^0_1}$ m t ~ < m W + m b + m χ ~ 1 0 (with $m_{{\tilde{t}}}-m_{{\tilde{\chi }}^0_1}\ge 5$ m t ~ - m χ ~ 1 0 ≥ 5 GeV), considered for the first time in an ATLAS all-hadronic search, top squark masses in the range 300–660 GeV are excluded. Limits are also set for scalar third-generation up-type leptoquarks, excluding leptoquarks with masses below 1240 GeV when considering only leptoquark decays into a top quark and a neutrino.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Long-lived isomeric states and quasiparticle band structures in neutron-rich 162,164 Gd nuclei from β decay
Neutron-rich nuclei 162,164 Eu were produced by bombarding a proton beam on a 238 U target at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory and mass separating the 162,164 Eu products. New level schemes and new γ-ray transitions of the daughters 162,164 Gd were identified from β-decay spectroscopy studies. Additionally, half-lives of the 162,164 Eu were remeasured to clarify the previous ambiguous results. Two quasiparticle band structures were built and compared with neighboring nuclei. The β and γ bands were extended in 162 Gd and a γ band was extended in 164 Gd. Half-lives of the isomeric states at (6 - ) 1449 keV in 162 Gd and (4 - ) 1096 keV in 164 Gd were measured to be 99(3) μs and 0.56(3) μs, respectively. Projected shell model calculations were performed and found to be in good agreement with all of the experimental data.
150 ≤ A ≤ 189↗
Bay capping via acetylene addition to polycyclic aromatic hydrocarbons: Mechanism and kinetics
The bay-capping mechanism on PAH armchair edges and the kinetics of acetylene addition to 6–6–5 and 5–6–5 bays have been explored by ab initio/RRKM-ME calculations. The bays on the edges were modeled by C 21 H 11 and C 20 H 9 radicals produced by H abstractions from 7H-benzo[c]cyclopenta[e]pyrene and dicyclopenta[cf]pyrene. The C 20 H 9 + C 2 H 2 reaction is shown to have a low entrance barrier and to rapidly form the capped product, indaceno[2,1,8,7-cdefg]pyrene, along with ethynyl substituted dicyclopenta[cf]pyrene at temperatures above 1400 K. The reactivity of C 21 H 11 is shown to be governed by the location of the unpaired electron; the π radical R1 formed by H abstraction from the CH 2 group in 7H-benzo[c]cyclopenta[e]pyrene reacts with C 2 H 2 very slowly owing to a high entrance barrier, with the bay-capping rate constant approaching 10 -16 cm 3 molecule -1 s -1 only at temperatures above 2000K. Further, this result reaffirms that the growth of π aryl radicals via acetylene addition is inefficient and reflects the generally low reactivity of such radicals where the spin density is highly delocalized over the entire polyaromatic system. Alternatively, the σ C 21 H 11 radical R2 produced by H abstraction from the five-membered ring at the bay rapidly reacts with C 2 H 2 forming the bay-capped product, with the rate constant on the order of 10 -12 cm 3 molecule -1 s -1 at T≥1500K. Rate constants for the capping reactions at the 6–6–5 and 5–6–5 bays are compared with those at the 6–0–6, 6–6–6, and 6–5–6 bays. The site-specific bay-capping rate constants have been utilized in kMC simulations of the PAH growth and the results showed measurable differences when the 6–6–5 and 5–6–5 bay-capping reactions are taken into account, including an increase of the growth rate and the formation of closed-shell PAH and a rise of the number of embedded five-membered rings accompanied with a slight decrease of their overall amount.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗