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At least 541 records · Page 30

All sources NASA NTRS DOE OSTI

NASA NTRS2022

The International DORIS Service contribution to ITRF2020

For the realization of the 2020 International Terrestrial Reference Frame (ITRF2020), the International DORIS Service delivered to the International Earth Rotation and Reference Systems Service (IERS) a set of 1456 weekly solution files from 1993.0 to 2021.0 including station coordinates and Earth orientation parameters (EOPs). The data come from fourteen DORIS satellites: TOPEX/Poseidon, SPOT-2, SPOT-3, SPOT-4, SPOT-5, Envisat, Jason-1, Jason-2, Cryosat-2, Saral, HY-2A, Jason-3, Sentinel-3A and Sentinel-3B. In their processing, the four analysis centers which contributed to the DORIS combined solution used the latest time variable gravity models, the new mean pole and diurnal-subdiurnal tidal EOP models recommended by IERS. In addition, all the analysis centers included in their processing precise SPOT-5 solar panel angle values and quaternions for, at least, the Jason satellites. Furthermore, a new Alcatel phase center variation model was implemented for the ITRF2020 processing. The main objective of this study is to present the combination process and to analyze the impact of the new modeling on the performance of the new combined solution. Comparisons with the IDS contribution to ITRF2014 show that i) the application of the new phase center variations for the Alcatel DORIS ground antennas in the data processing combined with the gradual replacement over time of the Alcatel by Starec antennas implies a scale drift from 1993.0 to 2002.5 and ii) thanks to a better modeling of the surface forces on the satellites, the new combined solution shows smaller annual and 118-day signals in the geocenter. A new DORIS terrestrial reference frame was computed to evaluate the intrinsic quality of the new combined solution. That evaluation shows that over almost the full time span the intrinsic IDS scale values lie in a range of ±5 mm. After mid-2008, the new DORIS reference frame has an internal position consistency in North-East-Up better than 7.5 mm.

DORIS↗

NASA NTRSDate not supplied

Diagnosing Noise Features Of Internally Mixed, External Plug Exhaust Systems

In internally mixed exhaust systems, a lobed or forced mixer is employed to mix the core and bypass streams before they exit the common nozzle. For moderate bypass-ratio engines this marginally improves thrust, and provides a significant acoustic benefit. Indeed, it has been thought that a fully mixed jet creates the lowest noise you can get from a two-stream engine. Typically, the forced mixer system produces a bit more noise than a fully mixed equivalent jet, noise that has been called “excess noise”. In recent testing, this excess noise seemed to be amplified when an external plug was employed in the exhaust system to reduce boattail drag. Identifying the mechanism of this excess noise and mitigating it is key to creating commercial supersonic vehicles that are acoustically acceptable around airports. This paper adds to that investigation, analyzing results from recent tests where far-field acoustic data were acquired on two sets of flows with matched fully mixed flow conditions. One set of flows had a heated core stream, making it a dual-stream jet. The other set had both streams heated to the same temperature, making a single-stream jet that matched the fully mixed temperature and velocity of the dual-stream jet. These flows were tested in two lobed-mixer exhaust systems with internal and external plugs. Analysis of flow and noise data from the nozzles with combinations of single- and dual-stream flows, and with and without flight streams, gives insight into how and why the noise of the dual-stream and single-stream jet differ. One additive source, present in nozzles both with and without external plugs, comes from inside the nozzle, likely the internal shear layer coming off the lobed mixer. This noise source is not impacted by a change in flight stream and has a distinctive spectral directivity that is amplified by the presence of the external plug. Finding the exact source mechanism of this new source will be key to making the internally mixed exhaust systems reach their lowest possible sound level.

Noise prediction, supersonic, jet noise↗

NASA NTRSDate not supplied

Diagnosing Noise Features Of Internally Mixed, External Plug Exhaust Systems

Noise prediction↗

DOE OSTI2014

Secret Objective Standoff: International Safeguards Educational Exercise

The International Safeguards Regime, being so multi-faceted, can be overwhelming to those first introduced to its many components. The organizers and lecturers of workshops and courses on nonproliferation often provide a series of independent lectures and must somehow demonstrate the cohesive and effective nature of the system. An exercise titled The Secret Objective Standoff was developed to complement lectures with hands-on learning to assist participants in bringing all the many components (IAEA agreements, export controls, treaty obligations, international diplomacy, etc.) of the International Safeguards Regime together. This exercise divides participants into teams that are assigned the role of either a country or the IAEA and asks that they fully immerse themselves in their roles. The teams are then randomly assigned three unique and secret objectives that are intended to represent realistic and current geopolitical scenarios. Through construction, trading, or hoarding of four resources (experts, technology, money, and uranium), the teams have a finite number of turns to accomplish their objectives. Each turn has three phases random dispersal of resources, a timed discussion where teams can coordinate and strategize with others, and an action phase. During the action phase, teams inform the moderator individually and secretly what they will be doing that turn. The exercise has been tested twice with Oak Ridge National Laboratory personnel, and has been conducted with outside participants twice, in each case the experience was well received by both participants and instructors. This exercise provides instructors the ability to modify the exercise before or during game play to best fit their educational goals. By offering a range of experiences, from an in-depth look at specific components to a generalized overview, this exercise is an effective tool in helping participants achieve a full understanding the International Safeguards Regime.

Okowita, Samantha L↗

DOE OSTI2019

Container having an internal structure with minimum surfaces

An illustrative example container includes a plurality of internal support members having a surface contour that at least approximates a minimum surface. The plurality of internal support members collectively provide structural support for carrying loads on the container. The plurality of internal support members collectively establish a plurality of cavities for at least temporarily containing fluid. An outer shell is connected with at least some of the internal support members. The outer shell includes a plurality of curved surfaces. The outer shell encloses the cavities.

42 ENGINEERING↗

DOE OSTI2020

Internally-cooled compressor diaphragm

An internally-cooled diaphragm for an internally-cooled compressor is provided. The internally-cooled diaphragm may include an annular body configured to cool a process fluid flowing through a fluid pathway of the internally-cooled compressor. The annular body may define a return channel of the fluid pathway, and a cooling pathway in thermal communication with the fluid pathway. The return channel may be configured to at least partially diffuse and de-swirl the process fluid flowing therethrough, and the cooling pathway may be configured to receive a coolant to absorb heat from the process fluid flowing through the return channel.

42 ENGINEERING↗

DOE OSTI2022

Domestic and International Standards for Nuclear Criticality Safety – Overview and Status

The domestic and international consensus standards for nuclear criticality safety (NCS) have provided guidance for staff performing hands-on work in operations with fissionable materials. These consensus standards have contributed directly to the significant reduction in the rate of criticality accidents in process facilities since the 1940s. The last known criticality accident inside the United States was in 1978 (nearly 43 years ago) at the Idaho Chemical Processing Plant, and outside the United States, an accident occurred at Tokai-mura, Japan, in 1999 (23 years ago). The domestic consensus standards for NCS include the American Nuclear Society (ANS) standards. The ANS Standards Board, the NCS Consensus Committee, and the ANS-8 Subcommittee oversee the development and maintenance of these standards. There are currently eighteen standards in the ANS-8 series. Currently, there are six ANS-8 standards in revision mode and eleven in a maintenance mode with one new standard under development. The international consensus standards for NCS calculations, procedures, and practices are maintained and developed within the International Organization for Standardization (ISO), Technical Committee 85 on Nuclear Energy, Subcommittee 5 on Nuclear Fuel Technology, and Working Group 8, “Nuclear Criticality Safety.” Eleven standards are currently available, three standards are in revision mode, and two standards are development. This paper provides the NCS community with an overview and status report of domestic and international NCS consensus standards to stimulate interest and to support their continued development.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2022

Domestic and International Standards for Nuclear Criticality Safety - Overview & Status [Abstract]

The domestic and international consensus standards for nuclear criticality safety (NCS) have provided guidance for staff performing hands-on work in operations with fissionable materials. These consensus standards have contributed directly to the significant reduction in the rate of criticality accidents in process facilities since the 1940s. The last known criticality accident inside the United States was in 1978 (nearly 43 years ago) at the Idaho Chemical Processing Plant, and outside the United States, an accident occurred at Tokai-mura, Japan, in 1999 (22 years ago). The domestic consensus standards for NCS include the American Nuclear Society (ANS) standards. The ANS Standards Board, the NCS Consensus Committee, and the ANS-8 Subcommittee oversee the development and maintenance of these standards. There are currently eighteen standards in the ANS-8 series. Currently, there are six ANS-8 standards in re- vision mode and eleven in a maintenance mode with one new standard under development. The international consensus standards for NCS calculations, procedures, and practices are maintained and developed within the International Organization for Standardization, Technical Committee 85 on Nuclear Energy, Subcommittee 5 on Nuclear Fuel Technology, and Working Group 8, “Nuclear Criticality Safety.” Eleven standards are currently available, three standards are in revision mode, and two standards are development. This paper provides the NCS community with an overview and status report of domestic and international NCS consensus standards to stimulate interest and to support their continued development.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗

DOE OSTI2022

System and method for control of compression in internal combustion engine via compression ratio and elastic piston

The present disclosure relates to a system for controlling ignition of an air/fuel mixture intake charge directed into an internal combustion engine. The system may have a longitudinally movable inner cylinder liner configured to fit within a cylinder wall portion of an internal combustion engine, and able to receive a piston of the engine therein. A portion of the inner cylinder liner defines an internal volume forming a combustion chamber, and the internal volume controls a compression ratio of the cylinder. The system also has a cylinder head assembly operatively associated with the inner cylinder liner and able to move linearly to cause longitudinal displacement of the inner cylinder liner relative to the cylinder wall portion. This enables the volume of the combustion chamber to be further varied, to thus further vary the compression ratio.

Flowers, Daniel L.↗

DOE OSTI2017

EPRI Research Results: International Nuclear Power Plant Waste Classification - 17444

Different countries around the globe use varying schemes for the classification of radioactive waste. Many countries develop country specific waste classification schemes based on the International Atomic Energy Agency (IAEA) waste classification framework. The United States of America use the Class A, B, and C waste classification. Additionally, some countries use concentration limits to classify wastes while others use dose rate limits or a combination of concentration and dose rate limits. General comparisons have been made between the IAEA and the United States classification schemes, but a clear and well researched comparison of the international schemes was not evident in the available research data sets. In 2013 Electric Power Research Institute (EPRI) initiated the Comparison of Global Low and Intermediate Level Waste Management Methods project. The objective of the project was to understand how six countries managed their low and intermediate level wastes from generation to disposal. A major task of this project was to conduct a comparison of the international waste classification schemes. EPRI developed a set of reference waste volumes that are representative of nuclear power plant low-level radioactive waste in form and radioactivity concentrations (e.g. dry active waste, high activity resin, low activity resin, high activity filters and low activity filters). These waste volumes were then classified using the waste classification systems in place in several countries around the world. In 2016, EPRI presented a paper providing a status update on this research. This 2017 paper provides the final results of that research, show where comparisons and correlations can be made, and provide a discussion on how this information might inform international radioactive research and development and benchmarking of radioactive waste management strategies, operational experiences, best practices, and technology implementation. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2016

Importance of Upfront Preparatory Works for Vessel Internals Segmentation Projects - 16096

For more than thirty years, Westinghouse has been involved in reactor internals segmentation activities in the U.S. and Europe. Westinghouse completed in 2015 the segmentation of the reactor vessel and reactor vessel internals at the Jose Cabrera nuclear power plant in Spain and a similar project is on-going at Chooz A in France. Four more major reactor internals segmentation projects have been recently awarded in Sweden (Barsebaeck 1-2) and in Germany. (Philippsburg 1 and Neckarwestheim 1). For all reactor dismantling projects, it is essential that all activities are thoroughly planned and discussed upfront together with the customer. Detailed planning is crucial for achieving a successful project. One key activity in the preparation phase is the 'Segmentation and Packaging Plan' that documents the sequential steps required to segment, separate, and package each individual component, based on an activation analysis and component characterization study. Detailed procedures and specialized rigging equipment have to be developed to provide safeguards for preventing certain identified risks. The preparatory work can include some plant civil structure modifications for making the segmentation work easier and safer. Some original plant equipment is sometimes not suitable enough and need to be replaced. Before going to the site, testing and qualification are performed on full scale mock-ups in a specially designed pool for segmentation purposes. The mockup testing is an important step in order to verify the function of the equipment and minimize risk on site. This paper is describing the typical activities needed for preparing the reactor internals segmentation activities using under water mechanical cutting techniques. It will provide experiences and lessons learned that Westinghouse has collected from its recent projects and that will be applied for the new awarded projects. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2025

Domestic and International Consensus Standards for Nuclear Criticality Safety - Overview & Status

The domestic and international consensus standards for nuclear criticality safety (NCS) were developed based on the lessons-learned from process criticality accidents. These consensus standards were developed to reduce the rate of process criticality accidents in facilities that process, store, handle, or transport fissionable materials by hand. After a significant increase in criticality accidents through the mid-1960s, the rate of criticality accidents decreased as a result of these standards, and the criticality accident rate is extremely low from an industrial safety perspective. The last known criticality accident inside the United States was in 1978 (nearly 47 years ago) at the Idaho Chemical Processing Plant, and outside the United States, an accident occurred at Tokai-mura, Japan, in 1999 (almost 26 years ago). The domestic consensus standards for NCS include the American National Standards (ANS) that are prepared and published by the American Nuclear Society and approved by the American National Standards Institute (ANSI). The ANS Standards Board, the NCS Consensus Committee, and the ANS-8 Subcommittee oversee the development and maintenance of these standards. There are currently 18 standards in the ANS-8 series. Nine ANS-8 standards are either in revision mode or planned for revision. A new standard for the use of nondestructive assay measurements (ANSI/ANS-8.28-2024) for NCS was approved in March of 2024. The international consensus standards for NCS calculations, procedures, and practices are maintained and developed within the International Organization for Standardization, Technical Committee 85 “Nuclear Energy,” Subcommittee 5, “Nuclear Fuel Technology,” and Working Group 8, “Nuclear Criticality Safety.” Eleven standards are currently available, four standards are proposed for revision, and four standards are at various stages of development. This paper provides the NCS community with a high-level overview and status report of domestic and international NCS consensus standards to stimulate interest and to support their continued development.

Bowen, Douglas G [ORNL] (ORCID:0000000212460026)↗

DOE OSTI2022

A Phase-Field Study on Internal to External Oxidation Transition in High-Temperature Structural Alloys

Structural alloys applied at high temperatures rely on an external dense layer of oxide scale for protection. As some reactive alloy components are selectively oxidized internally, understanding how these dispersed metal oxide particles reach the surface to form a protective scale—the so-called internal to external oxidation transition—is crucial for designing these alloys. While the literature is replete with experimental studies on oxidation of alloys, there is a lack of computational studies in this realm due to the complex nature of coupled reaction and diffusion processes in multicomponent multi-phase alloy systems. In this work, we apply a recently developed phase-field model to simulate the oxidation processes under different compositions and nucleation scenarios to gain insights into how a continuous oxide scale can be established. The results show that while alloy composition is critical for internal to external oxidation transition, the oxide nuclei size, shape and distribution also have significant impact on the transition kinetics.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Research Tool to Evaluate the Safety Response of Lithium Batteries to an Internal Short Circuit

Li-ion cells provide the highest specific energy and energy density rechargeable battery with the longest life. Many safety incidents that take place in the field originate due to an internal short that was not detectable or predictable at the point of manufacture. NREL's internal short circuit (ISC) device is capable of simulating shorts and produces consistent and reproducible results. The cell behaves normally until the ISC device is activated wherein a latent defect (i.e., built into the cell during manufacturing) gradually moves into position to create an internal short while the battery is in use, providing relevant data to verify abuse models. The ISC device is an effective tool for studying the safety features of parts of Li-ion batteries.

25 ENERGY STORAGE↗

DOE OSTI2015

NREL/NASA Internal Short-Circuit Instigator in Lithium Ion Cells

Lithium-ion cells provide the highest specific energy (>280 Wh/kg) and energy density (>600 Wh/L) rechargeable battery building block to date with the longest life. Electrode/electrolyte thermal instability and flammability of the electrolyte of Li-ion cells make them prone to catastrophic thermal runaway under some rare internal short circuit conditions. Despite extensive QC/QA, standardized industry safety testing, and over 18 years of manufacturing experience, major recalls have taken place and incidents still occur. Many safety incidents that take place in the field originate due to an internal short that was not detectable or predictable at the point of manufacture. The Internal Short-Circuit Instigator can be used to study types of separators, non-flammable electrolytes, electrolyte additives, fusible tabs, propagation studies, and gas generation within a cell.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2020

Use of a Pressurized Water Treatment to Prevent Cracking of Internal Gelation Sol-Gel Microspheres

Pressurized water treatments were investigated as a means to prevent cracking of internal gelation sol-gel microspheres upon drying and heating. A batch of gelled cerium oxide microspheres was prepared, split into two samples that were processed with and without a pressurized water treatment, and dried in air at room temperature. Thermal gravimetric analysis was used to compare the mass loss profiles between the two samples and to understand volatile emissions from cerium oxide microspheres during heat treatments up to 600 °C. Microspheres that were processed without a pressurized water treatment lost approximately 4.6 times more mass upon heating than microspheres that were subjected to a pressurized water treatment. Comparison of the cracking behavior of microspheres prepared with and without a pressurized water treatment indicated that microspheres subjected to a pressurized water treatment were virtually crack-free after heat treatments. Conversely, microspheres processed without a pressurized water treatment, which is typical of traditional washing processes, exhibited extensive cracking. Analysis of residues dried from pressurized water treatment effluents indicated that hexamethylenetetramine and urea, which are excess reactants from the internal gelation process, were removed from gelled microspheres during the pressurized water treatment step. Traditional processing methods for preparing internal gelation microspheres use specific feed solution and gelation parameters to reduce subsequent cracking upon drying and heating. Results from this study indicate that more aggressive gel-forming conditions may be used to produce crack-free microspheres, if a pressurized water treatment step is included after washing and before air-drying.

cerium oxide, internal gelation, microsphere, TRIS↗

DOE OSTI2023

Observation and Modeling of the Thermal Runaway of High-Capacity Pouch Cells Due to an Internal Short Induced by an Indenter

Owing to the complexity of coupling mechanical and electrical solvers for finite element analysis (FEA) of mechanical abuse of a battery, the simulation should be performed by incorporating a local short circuit model activated based on the status of battery elements. However, the approach should also consider various other conditions of the battery simulated, such as the initial state of charge (SOC), for precise simulations of the internal short. This study proposes an approach developed with a mechanical model and single-particle battery model, along with a reaction kinetics model for thermal abuse using LS-DYNA. Several key parameters were selected, such as the activation criteria, kinetic abuse and element integration points during the internal short circuit induced by the indenter. The impact of these key parameters in the FEA on thermal runaway response for various initial SOCs from 25 to 100 % were analyzed. The FEA results obtained were compared against experimental results with various parameters such as activation criterion of internal short, kinetic abuse based on accelerating rate calorimetry (ARC) data. Finally, the root causes of the discrepancy between the FEA and experimental results are discussed regarding integration point what solver can make difference during calculation.

ENERGY STORAGE↗

DOE OSTI2025

DECOVALEX-2023: An international collaboration for advancing the understanding and modeling of coupled thermo-hydro-mechanical-chemical (THMC) processes in geological systems

The DECOVALEX initiative is an international research collaboration (www.decovalex.org), initiated in 1992, for advancing the understanding and modeling of coupled thermo-hydro-mechanical-chemical (THMC) processes in geological systems. DECOVALEX stands for “DEvelopment of COupled Models and VALidation against EXperiments”. The creation of this international initiative was motivated by the recognition that prediction of these coupled effects is an essential part of the performance and safety assessment of geologic disposal systems for radioactive waste and spent nuclear fuel. DECOVALEX emphasizes joint analysis and comparative modeling of the complex perturbations and coupled processes in geologic repositories and how these impact long-term performance predictions. The most recent phase of the DECOVALEX Project, here referred to as DECOVALEX-2023, started in early 2020 and ended in late 2023. More than fifty research teams associated with 17 international DECOVALEX partner organizations participated in the comparative evaluation of eight modeling tasks covering a wide range of spatial and temporal scales, geological formations, and coupled processes. This Virtual Special Issue on DECOVALEX-2023 provides an in-depth overview of these collaborative research efforts and how these have advanced the state-of-the-art of understanding and modeling coupled THMC processes. While primarily focused on radioactive waste, much of the work included here has wider application to many geoengineering topics.

Coupled processes↗