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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3

Understanding the efficacy of concentrated interstitial carbon in enhancing the pitting corrosion resistance of stainless steel

By introducing a high fraction of interstitial carbon through low temperature carburization, the pitting corrosion resistance of austenitic stainless steel can be significantly improved. Previous work attributed this to strengthening of the passive film by carbon. Here, however, we present a paradigm shift by showing that carbon actually weakens the passive film but strengthens the bonding within the alloy by forming localized (covalent) bonds with the metal atoms (Fe, Cr, Ni). Accordingly, the enhancement in pitting resistance is a result of carbon reducing the metal dissolution rate in a local pit environment by many orders of magnitude, which extremely decreases the growth stability of a pit and prevents it from transitioning into stable growth. Electronic structure calculations confirm that carbon bonds to the metal atoms and that the metal–carbon bonds are 1.4 to 2.0 times stronger than the metal–metal bonds. These results suggest a new strategy for the design of corrosion resistant alloys, namely surface engineering by infusion of concentrated interstitials that form strong bonds with the matrix atoms.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Iraq/Afghanistan war lung injury reflects burn pits exposure

This descriptive case series retrospectively reviewed medical records from thirty-one previously healthy, war-fighting veterans who self-reported exposure to airborne hazards while serving in Iraq and Afghanistan between 2003 and the present. They all noted new-onset dyspnea, which began during deployment or as a military contractor. Twenty-one subjects underwent non-invasive pulmonary diagnostic testing, including maximum expiratory pressure (MEP) and impulse oscillometry (IOS). In addition, five soldiers received a lung biopsy; tissue results were compared to a previously published sample from a soldier in our Iraq Afghanistan War Lung Injury database and others in our database with similar exposures, including burn pits. We also reviewed civilian control samples (5) from the Stony Brook University database. Military personnel were referred to our International Center of Excellence in Deployment Health and Medical Geosciences, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell under the auspices of Northwell IRB: 17-0140-FIMR Feinstein Institution for Medical Research “Clinicopathologic characteristics of Iraq Afghanistan War Lung Injury.” We retrospectively examined medical records, including exposure data, radiologic imaging, and non-invasive pulmonary function testing (MGC Diagnostic Platinum Elite Plethysmograph) using the American Thoracic Society (ATS) standard interpretation based on Morgan et al., and for a limited cohort, biopsy data. Lung tissue, when available, was examined for carbonaceous particles, polycyclic aromatic hydrocarbons (Raman spectroscopy), metals, titanium connected to iron (Brookhaven National Laboratory, National Synchrotron Light Source II, Beamline 5-ID), oxidized metals, combustion temperature, inflammatory cell accumulation and fibrosis, neutrophil extracellular traps, Sirius red, Prussian Blue, as well as polarizable crystals/particulate matter/dust. Among twenty-one previously healthy, deployable soldiers with non-invasive pulmonary diagnostic tests, post-deployment, all had severely decreased MEP values, averaging 42% predicted. These same patients concurrently demonstrated abnormal airways reactance (X5Hz) and peripheral/distal airways resistance (D5–D20%) via IOS, averaging – 1369% and 23% predicted, respectively. These tests support the concept of airways hyperresponsiveness and distal airways narrowing, respectively. Among the five soldiers biopsied, all had constrictive bronchiolitis. We detected the presence of polycyclic aromatic hydrocarbons (PAH)—which are products of incomplete combustion—in the lung tissue of all five warfighters. All also had detectable titanium and iron in the lungs. Metals were all oxidized, supporting the concept of inhaling burned metals. Combustion temperature was consistent with that of burned petrol rather than higher temperatures noted with cigarettes. All were nonsmokers. Neutrophil extracellular traps were reported in two biopsies. Compared to our prior biopsies in our Middle East deployment database, these histopathologic results are similar, since all database biopsies have constrictive bronchiolitis, one has lung fibrosis with titanium bound to iron in fixed mathematical ratios of 1:7 and demonstrated polarizable crystals. These results, particularly constrictive bronchiolitis and polarizable crystals, support the prior data of King et al. (N. Engl. J. Med. 365:222–230, 2011) Soldiers in this cohort deployed to Iraq and Afghanistan since 2003, with exposure to airborne hazards, including sandstorms, burn pits, and improvised explosive devices, are at high risk for developing chronic clinical respiratory problems, including: (1) reduction in respiratory muscle strength; (2) airways hyperresponsiveness; and (3) distal airway narrowing, which may be associated with histopathologic evidence of lung damage, reflecting inhalation of burned particles from burn pits along with particulate matter/dust. Non-invasive pulmonary diagnostic tests are a predictor of burn pit-induced lung injury

36 MATERIALS SCIENCE↗

An initial effort to study the influence of pitting in SAVY containers

As part of a broader effort to investigate a critical pit depth, below which SAVY containers fail a leak test after a drop test, surrogate testing using pristine SAVY container material was investigated. The original study involved producing pits in a SAVY wall to depths 35% to 55% of the wall thickness and subjecting the pitted container to a drop test under prototypic conditions. Subsequent leak testing after drop testing showed the container passed and that the pit size distribution and drop conditions were not sufficient to cause a leak test failure in this specific container.

36 MATERIALS SCIENCE↗

Pitting behavior of friction stir repair-welded 304L stainless steel in 3.5% NaCl solution at room temperature: role of grain and defect structures

Stainless steel (SS) canisters used for storing spent nuclear waste are prone to chloride-induced stress corrosion cracking. Friction stir welding (FSW), being a low heat input process, can be used for repair welding of these canisters. In this study, an artificial crack was introduced on the 304L SS coupons by an electric discharge machining process. The artificial crack was repair-welded by FSW by maintaining the tool temperature a constant at two levels (725 and 825 °C). Friction stirring significantly reduced the grain size of the stirred zone (SZ) from about 47 to 2–4 μm. The fraction of low-angle grain boundaries increased in the SZ from 2 to 37–43%. Here, on the other hand, the fraction of special grain boundaries (Σ3 and Σ9) that was ~ 50% in the base metal reduced to < 10% in the SZ. During friction stirring, the oxide layer of artificial crack was broken and aligned to form a spiral defect called lazy-S structure. All these microstructural changes affected the corrosion behavior of the FSW specimens when tested in 3.5% NaCl at room temperature using cyclic polarization, chronoamperometry, and electrochemical impedance spectroscopy. The FSW specimens showed lower polarization resistance and lower transpassive potential than those of the base metal specimens. However, the pitting protection potentials of the FSW specimens were higher than that of the base metal. The pitting behavior of the FSW specimens was influenced more by the preferential attack on the lazy-S region than by passive film breakdown. The flat band potentials of the passive film formed on the FSW specimens were more positive than that of base metal. The charge carrier density of passive film formed on the FSW specimens was higher than that of the base metal. The higher fraction of low-angle grain boundaries present in the FSW specimens could supply more number of misorientation dislocations at the metal/film interface which could form anion vacancies by a climb process leading to formation of oxide at these locations without stressing the substrate. Therefore, low-angle boundaries are considered helpful for formation of stress-free passive films that will be highly stable and enhance both pitting and stress corrosion cracking resistance.

Dry storage canister↗

Critical pitting temperature of selective laser melted 316L stainless steel: A mechanistic approach

In this work, the critical pitting temperature (CPT) of selective laser melted (SLM) 316 L stainless steel in 1.0 M NaCl was measured and compared with a commercial wrought alloy. Potentiostatic measurements determined a mean CPT value of 16 ± 0.7 °C, 27.5 ± 0.8 °C and 31 ± 1 °C for the wrought alloy, the SLM alloy normal to the build direction and parallel to the build direction, respectively. The lead-in pencil electrode technique was used to study the pit chemistry of the two alloys and to explain the higher CPT values observed for the SLM alloy. A lower critical current density required for passivation in a simulated pit solution was measured for the SLM alloy. Moreover, the ratio of the critical concentration to saturated concentration of dissolving metal cations was found to be higher for the SLM alloy, which was related to its different salt film properties, possibly as a result of the SLM’s distinct microstructure.

36 MATERIALS SCIENCE↗

CMP Pits and D-Area Watershed Infiltrometer Testing

Savannah River National Laboratory (SRNL) conducted saturated hydraulic conductivity field testing at the Chemical, Metals, and Pesticide Pits (CMP Pits) and the D-Area watershed to develop infiltration rates for use in future updates to the CMP Pits groundwater flow model. Approximately 18 testing locations were selected at each site based on the soil series that were identified in the Soil Survey of Savannah River Plant Area, Parts of Aiken, Barnwell, and Allendale Counties, South Carolina.

54 ENVIRONMENTAL SCIENCES↗

CMP Pits and D-Area Watershed Infiltrometer Testing

Savannah River National Laboratory (SRNL) conducted saturated hydraulic conductivity field testing at the Chemical, Metals, and Pesticide Pits (CMP Pits) and the D-Area watershed to develop infiltration rates for use in future updates to the CMP Pits groundwater flow model. Approximately 18 testing locations were selected at each site based on the soil series that were identified in the Soil Survey of Savannah River Plant Area, Parts of Aiken, Barnwell, and Allendale Counties, South Carolina.

54 ENVIRONMENTAL SCIENCES↗

Effect of Oil Viscosity and Impact of Ionic Liquid Additive on Electrically Induced Pitting in Rolling Contact

Electrically induced bearing damage (EIBD) is a growing concern in electric drivetrains, where electrical discharge currents generate localized pitting that accelerates wear and premature failure. While ionic liquids (ILs) have shown promise as lubricant additives due to their natural physical adsorption, strong capabilities of tribofilm formation, and high molecular tunability, their role in mitigating EIBD is little known. This gap is especially evident because lubricant viscosity and film thickness affect discharge behavior, and additive performance in these regimes has not been well explored. In this study, tribological tests were performed using a ball-on-disk pure rolling-contact system under an applied voltage on polyalphaolefin oils of three viscosities (4, 10, and 150 cSt measured at 100 °C), with and without the addition of a phosphonium-phosphate IL. Surface damage was analyzed using scanning electron microscopy (SEM) and stylus profilometry. Damage quantification was based on pit morphology analysis of SEM images. The results provide new insights into how oil viscosity governs the discharge behavior and how an IL additive could influence the pit formation. While viscosity seems to play a significant role, an IL additive shows potential to reduce EIBD and deserves further study.

electrically induced bearing damage (EIBD)↗

National Geographic Interview -- Pit Manufacturing

Los Alamos has been contacted by a freelance reporter working on assignment for National Geographic, Sarah Scoles. Scoles is working on a story about plutonium pit production. She says the story will be an explainer -- detailing the pit production process from start to finish, in context with the planned increase in production. Scoles is seeking to interview a LANL expert or experts to help explain the process, the Lab's history in pit production, and future role.

36 MATERIALS SCIENCE↗

Slug Test Characterization Results for the Upper Three Runs Aquifer at the Chemicals, Metals, and Pesticides Pits Operable Unit

Slug tests were performed on 21 wells screened within the Upper Three Runs aquifer (UTRA) at the Chemical, Metals, and Pesticide (CMP) Pits Operable Unit (OU) to determine unit-specific hydraulic properties. The UTRA is the water table aquifer at CMP Pits and is comprised of three discrete zones that are separated by two semi-continuous confining zones. These zones include the transmissive zone (TZ, unconfined), the middle aquifer zone (MAZ, semi-confined), and the lower aquifer zone (LAZ, semi-confined). The LAZ, the most substantial portion of the UTRA in the area, extends vertically to the green clay confining zone (GCCZ). A subset of wells from each zone was selected for slug testing. The objective of the project was to determine hydraulic properties of the three zones of the UTRA for use in future updates to the CMP pits groundwater flow and contaminant transport modeling.

54 ENVIRONMENTAL SCIENCES↗

Development of a Multi-Robot System for Autonomous Inspection of Nuclear Waste Tank Pits

This paper introduces the overall design plan, development timeline, and preliminary progress of the Autonomous Pit Exploration System project. This project aims to develop an advanced multi-robot system for the efficient inspection of nuclear waste-storage tank pits. The project is structured into three phases: Phase 1 involves data collection and interface definition in collaboration with Hanford Site experts and university partners, focusing on tank riser geometry and hardware solutions. Phase 2 includes the selection of sensors and robot components, detailed mechanical design, and prototyping. Phase 3 integrates all components into a cohesive system managed by a master control package which also incorporates digital twin and surrogate models, and culminates in comprehensive testing and validation at a simulated tank pit at the Idaho National Laboratory. Additionally, the system’s communication design ensures coordinated operation through shared data, power, and control signals. For transportation and deployment, an electric vehicle (EV) is chosen to support the system for a full 10 h shift with better regulatory compliance for field deployment. A telescopic arm design is selected for its simple configuration and superior reach capability and controllability. Preliminary testing utilizes an educational robot to demonstrate the feasibility of splitting computational tasks between edge and cloud computers. Successful simultaneous localization and mapping (SLAM) tasks validate our distributed computing approach. More design considerations are also discussed, including radiation hardness assurance, SLAM performance, software transferability, and digital twinning strategies.

Nuclear waste management↗

Refinement of Pitting Factor Basis to Support the Corrosion Control Program (Interim Report)

At Savannah River Site (SRS), High-Level Waste is stored in below-grade tanks constructed of carbon steel. This waste is composed of sludge, salt cake, and/or supernate. In part, preparation of this waste for future processing involves dissolution of the salt cake layer. The salt dissolution process can create conditions that leave the carbon steel tanks susceptible to a number of corrosion processes. The salt to be dissolved contains high concentrations of nitrate, that once released, create an environment that may be conducive to pitting corrosion or stress corrosion cracking (SCC) of carbon steel. Additionally, during the salt dissolution process, in the absence of mixing, stratification of the supernatant liquid may occur. This can result in less dense, more dilute waste layers occurring higher in the tank. In these more dilute waste layers, the susceptibility to localized corrosion could potentially differ from that of the more concentrated salt solutions evaluated in previous testing, as the amount of inhibiting and aggressive species, not just the ratios, can affect susceptibility. Evaluation of the susceptibility to localized corrosion in these more dilute waste chemistries could provide insight into the amount of inhibitors required to effectively mitigate pitting corrosion in stagnant salt dissolution environments, as well as other tank farm operations involving dilute waste streams.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Monitored Natural Attenuation (MNA) Assessment for the Chemicals, Metals, and Pesticides (CMP) Pits Operable Unit (OU) and the Pen Branch Wetland

In October 2024, Savannah River National Laboratory (SRNL) was tasked to conduct an independent review of groundwater data and assess the monitored natural attenuation (MNA) performance related to the Chemicals, Metals, and Pesticides (CMP) Pits Operable Unit (OU) located in the central portion of the Savannah River Site (SRS). The SRNL assessment of MNA entailed an independent analysis of groundwater concentration data, groundwater elevation data, available surface water concentration data, soil concentration data, and relevant historical geological characterization logs for the CMP Pits OU. Historical data tables and records were obtained from both the Savannah River Nuclear Solutions - Area Completion Projects (SRNS&#x2;ACP) team and South Carolina State University (SCSU) and condensed into new data sets by the SRNL project team for more targeted analysis of MNA performance characteristics. All data pertaining to groundwater concentration, surface water concentration, and groundwater elevation were restricted to collection dates after any known active remediation for the CMP OU.

54 ENVIRONMENTAL SCIENCES↗

Exploring 3D leaf anatomical traits for C 4 photosynthesis: chloroplast and plasmodesmata pit field size in maize and sugarcane

Summary Volume and surface area of chloroplasts and surface area of plasmodesmata pit fields are presented for two C 4 species, maize and sugarcane, with respect to cell surface area and cell volume. Serial block face scanning electron microscopy (SBF‐SEM) and confocal laser scanning microscopy with the Airyscan system (LSM) were used. Chloroplast size estimates were much faster and easier using LSM than with SBF‐SEM; however, the results were more variable than SBF‐SEM. Mesophyll cells were lobed where chloroplasts were located, facilitating cell‐to‐cell connections while allowing for greater intercellular airspace exposure. Bundle sheath cells were cylindrical with chloroplasts arranged centrifugally. Chloroplasts occupied c. 30–50% of mesophyll cell volume, and 60–70% of bundle sheath cell volume. Roughly 2–3% of each cell surface area was covered by plasmodesmata pit fields for both bundle sheath and mesophyll cells. This work will aid future research to develop SBF‐SEM methodologies with the aim to better understand the effect of cell structure on C 4 photosynthesis.

3D leaf imaging↗

Pit Production Strategic Analysis Tool

The LANL Pit Production Strategic Analysis tool is an executive-level decision support tool for planning related to the demand and production of pits. The spreadsheet-based tool includes decision factors for stockpile program demand combined with production and infrastructure planning at PF-4, Savanna River, and future production options. The tool graphically compares supply and demand under different scenarios. The tool is based on NNSA planning documents and process analyses.

97 MATHEMATICS AND COMPUTING↗

Pits 101: The true meaning of deterrence

Mark Davis (ALDWP-COO) is the Chief Operation Officer for the Associate Laboratory Directorate of Weapons Production, where he focuses on ramping up operations in the Plutonium Facility in support of the directorate's programs, including the plutonium pit mission. Davis has had an accomplished career in the U.S. Navy that has compelled him to inspire those who support our nation's national security through sharing stories of our nation's history and the individuals who have been world-changers. He is passionate not only about our national security mission here at the Lab, but also about ensuring every employee understands that they play a key role in the mission, no matter their day job. In this special edition of the Pits 101 series, Public Affairs sat down with Davis to get his perspective on the meaning of credible and sustainable strategic deterrence, and why it matters today.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

NGEE Arctic Soil Pit and Core Inventory for Samples Collected Between 2016-2019: Locations, Sampling Characteristics, Collection, and Contacts, Seward Peninsula, Alaska, USA

This dataset includes associated information about individual pit and core samples (e.g., location, contact, date, data collected) sampled between 2016 and 2019 from NGEE Arctic sites at Teller (MM 27 and MM47), Kougarok (MM47 and MM56, Hillslope, and vegetation plot areas), and Council (MM71). The inventory is qualitative and excludes those datasets on soil pit cores that included time-series information. The package includes one each *.csv data file, *.kml and *.pdf. All quantitative data is available in the related datasets https://doi.org/10.5440/1417652, https://doi.org/10.5440/1423892, https://doi.org/10.5440/1342956, https://doi.org/10.5440/1854940, https://doi.org/10.5440/1544760, https://doi.org/10.5440/1346200, and https://doi.org/10.5440/1856042. The goal of this dataset is to help modelers understand when, where, and what data was collected with respect to physical soil properties on the Seward Peninsula, AK, USA over the course of NGEE Arctic’s campaigns in the region from 2016-2019. The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was a research effort to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research. The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska. Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

54 ENVIRONMENTAL SCIENCES↗

A space-time adaptive finite element method with exponential time integrator for the phase field model of pitting corrosion

In this paper we propose a space-time adaptive finite element method for the phase field model of pitting corrosion, which is a parabolic partial differential equation system consisting of a phase variable and a concentration variable. A major challenge in solving this phase field model is that the problem is very stiff, which makes the time step size extremely small for standard temporal discretizations. Another difficulty is that a high spatial resolution is required to capture the steep gradients within the diffused interface, which results in very large number of degrees of freedom for uniform meshes. To overcome the stiffness of this model, we combine the Rosenbrock–Euler exponential integrator with Crank–Nicolson scheme for the temporal discretization. Moreover, by exploiting the fact that the speed of the corroding interface decreases with time, we derive an adaptive time stepping formula. For the spatial approximation, we propose a simple and efficient strategy to generate adaptive meshes that reduces the computational cost significantly. Thus, the proposed method utilizes local adaptivity and mesh refinement for efficient simulation of the corrosive dissolution over long times in heterogeneous media with complex microstructures. We also present an extensive set of numerical experiments in both two and three dimensional spaces to demonstrate efficiency and robustness of the proposed method.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗