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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

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↗
DOE OSTI2025

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↗
DOE OSTI2025

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↗
DOE OSTI2019

Plutonium Pit Production

A plutonium pit is a key component of a nuclear weapon. During the Cold War, the United States produced approximately 1,000 pits per year at the Rocky Flats Plant in Colorado. Rocky Flats was closed in 1992 and today the United States does not have the capability to manufacture new pits at the rate needed to maintain the nuclear deterrent. A delay in revitalizing this capability will eventually necessitate a larger, more expensive recapitalization effort in the future.

Source record↗
DOE OSTI2017

Simulated Impacts of Water Introduced into Pits 37 and 38 at Technical Area 54, Area G, Los Alamos National Laboratory - 17386

Water is used in the disposal of bulk waste generated by cleanup activities at LANL, including large quantities of waste retrieved from Material Disposal Area (MDA) B. This water is used to wash material from the metal bins in which the material is transported to Area G, to decontaminate the containers so they can be returned to service, to decontaminate the trucks used to transport the bins, and for general dust suppression during waste placement. The introduction of this water into pits 37 and 38 at Area G during disposal of MDA B waste in those pits may affect the rates at which water percolates through, and leaches contaminants from, the waste in the disposal pits, and thus may hasten the transport of contamination to the regional aquifer below the disposal facility. A special analysis was conducted to evaluate the potential impacts of the water used during bulk waste disposal on the long-term performance of the disposal facility. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

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↗
DOE OSTI2018

Phase-field model of pitting corrosion kinetics in metallic materials

This study presents a thermodynamically consistent phase field model for the quantitative prediction of the pitting corrosion kinetics in metallic materials. An order parameter is introduced to represent the metal’s physical state at each point in the entire domain. The free energy of the metal-electrolyte system is defined in terms of its metal ion concentration and the order parameter. The mass transport in the electrolyte and the electrochemical reactions in the electrolyte/metal interface are taken into consideration in the model to simulate metal corrosion in a corrosive environment. The governing equations for mass transport and the order parameter are solved in such a manner that the system’s free energy is reduced as a result of diffusion and migration processes, and the distribution of electrostatic potential is governed by Poisson’s equation. A calibration study is performed to couple the kinetic interface parameter with the corrosion current density, which results in a direct relationship between overpotential and the kinetic interface parameter. A comparative study is performed to validate the phase field model against the experimental results. Several case studies are also examined to understand the corrosion behavior of closely located pits, stressed material, ceramic particles-reinforced steel, and crystallographic orientation dependence.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Improvement of small to large grain A15 ratio in Nb 3 Sn PIT wires by inverted multistage heat treatments

The next generation of superconducting accelerator magnets for the Large Hadron Collider at CERN will require large amounts of Nb 3 Sn superconducting wires and the Powder-In-Tube (PIT) process, which utilizes a NbSn 2 -rich powder core within tubes of Nb(7.5wt%Ta) contained in a stabilizing Cu matrix, is a potential candidate. But, the critical current density, J c , is limited by the formation of a large grain (LG) A15 layer which does not contribute to transport current, but occupies 25-30% of the total A15 area. Thus it is important to understand how this layer forms, and if it can be minimized in favor of the beneficial small grain (SG) A15 morphology which carries the supercurrent. The ratio of SG/LG A15 is our metric here, where an increase signals improvement in the wires A15 morphology distribution. We have made a critical new observation that the initiation of the LG A15 formation can be controlled at a wide range of temperatures relative to the formation of the small grain (SG) A15. The LG A15 can be uniquely identified as a decomposition product of the Nb6Sn5(Cu x ), surrounded by a layer of rejected Cu, thus the LG A15 is not only of low pin density, but is not continuous grain to grain. We have found that in single stage reactions limited to 630 °C - 690 °C, the maximum SG A15 layer thickness prior to LG A15 formation is very sensitive to temperature, with a maximum around 670 °C. This result led to the design of four novel heat treatments which all included a short, high temperature stage early in the reaction, followed by a slow cooling to a more typical reaction temperature of 630 °C. We also found that this heat treatment (HT) modification increased the SG A15 layer thickness while simultaneously suppressing LG A15 morphology, with no additional consumption of the diffusion barrier. In the best heat treatment the SG/LG A15 ratio improved by 30%. Unfortunately, J c values suffered slightly, however further exploration of this high temperature reaction region is required to understand the limits to A15 formation in Nb3Sn PIT conductors.

36 MATERIALS SCIENCE↗
DOE OSTI2025

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 (SRNSACP) 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↗
DOE OSTI2019

In Situ Monitoring of Pit Gas Composition During Baking of Anodes for Aluminum Electrolysis

Carbon anodes, which are consumed in aluminum electrolysis, are fabricated in separate anode plants where coke and pitch are mixed and vibrocompacted to green anode blocks before being baked in anode baking furnaces. The chemical environment inside an anode baking furnace is found to play an important role in the degradation of the furnace refractory lining. In this work, the pit gas composition was recorded during anode baking by a Fourier transformed infrared spectroscopy (FTIR) spectrometer and a gas chromatograph. The temperature dependence of the concentration of gas species during baking was obtained based on three measurement campaigns. The concentrations of CO and CO{sub 2} were found to be dependent on temperature, where the concentration of CO peaked around the maximum firing temperature. In addition to varying concentrations of CH{sub 4} and HF, water was found in large amounts in the first part of the baking cycle. The water originates to some extent from the cooling of the green anodes after vibrocompaction and is potentially important with respect to the chemical stability of the refractory lining. The variations in pit gas composition are related to operational parameters and are discussed in relation to refractory degradation phenomena.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Metalorganic vapor phase epitaxy of AlN on sapphire with low etch pit density

Using metalorganic vapor phase epitaxy, methods were developed to achieve AlN films on sapphire with low etch pit density (EPD). Key to this achievement was using the same AlN growth recipe and only varying the pre-growth conditioning of the quartz-ware. After AlN growth, the quartz-ware was removed from the growth chamber and either exposed to room air or moved into the N2 purged glove box and exposed to H2O vapor. After the quartz-ware was exposed to room air or H2O, the AlN film growth was found to be more reproducible, resulting in films with (0002) and (10–12) x-ray diffraction (XRD) rocking curve linewidths of 200 and 500 arc sec, respectively, and EPDs < 100 cm−2. The EPD was found to correlate with (0002) linewidths, suggesting that the etch pits are associated with open core screw dislocations similar to GaN films. Once reproducible AlN conditions were established using the H2O pre-treatment, it was found that even small doses of trimethylaluminum (TMAl)/NH3 on the quartz-ware surfaces generated AlN films with higher EPDs. The presence of these residual TMAl/NH3-derived coatings in metalorganic vapor phase epitaxy (MOVPE) systems and their impact on the sapphire surface during heating might explain why reproducible growth of AlN on sapphire is difficult.

Koleske, D. D.↗
DOE OSTI2023

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↗
DOE OSTI2017

Technology and Ecology of Dumping at Open Pit Mines in Kuzbass

The methods and means of overburden dumping at open pit coal mines in Kuzbass are reviewed. Specific features of dumping are highlighted, and the dependence of dump stability on geological conditions and physical properties of overburden is determined. The priority lines of development in the dumping technology are aimed at efficient utilization of mined-out areas in open pits and idle hydraulic fills. The issues of the environmental safety of dumping are addressed.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2022

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↗
DOE OSTI2023

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↗
DOE OSTI2022

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↗
DOE OSTI2016

Ablation layers to prevent pitting in laser peening

A hybrid ablation layer that comprises a separate under layer is applied to a material to prevent pitting resulting from laser peening. The underlayer adheres to the surface of the workpiece to be peened and does not have bubbles and voids that exceed an acceptable size. One or more overlayers are placed over and in contact with the underlayer. Any bubbles formed under the over layers are insulated from the surface to be peened. The process significantly reduces the incidence of pits on peened surfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2019

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↗