SEARCH · Search NASA
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Electronic navigational charts (ENCs) are vital for navigation and must be updated frequently as coastal bathymetric conditions change, but the current manual survey approach is costly, time-consuming, and limited in scope by available survey resources.
We can improve network pruning by leveraging the loss-topography extraction techniques used by projective integral updates for variational inference. Low-variance Hessians facilitate more aggressive pruning by providing better loss approximations when a parameter is removed.
This is a conference presentation updating the progress on the Stereo-DIC Challenge 2.0 Images
Update slides for CRADA between SNL and GA.
The use of sensitivity/uncertainty (S/U) methods in nuclear criticality safety (NCS) was established more than 25 years ago and has been increasing ever since. Recent interest in commercial applications involving uranium enrichments above 5 wt% 235 U has increased focus on demonstrating the applicability of existing critical experiments to this enrichment range. S/U techniques can also be particularly useful in assessing the similarity of new fuel forms in relation to those documented in existing published evaluations of benchmark critical experiments. Publishing updated recommendations for the use of these methods is thus important to ensure that new S/U practitioners can benefit from the years of development and application invested in generating a set of best practices to maximize the utility of these tools.
Hector V3.2.0 is the version documented in Dorheim et. al (accepted in GMD), the changes between the previous version coupled with GCAM were in response to the reviewer feedback. We corrected aerosol forcing coefficients based on Zelinka et al. (2023), enabled the permafrost module to be on by default, and recalibrated the model. These changes mean that we had to update the hector-gcam.ini file, it also causes some changes in Hector output behavior (described below) which may have implications on GCAM runs. Ultimately Hector is cooler by about 0.15 degrees, although this is scenario dependent.
The USA Structures (USS) foundational data layer remains a critical national dataset for supporting damage assessment and disaster response across the United States. Maintaining its relevance requires regular updates to reflect changes in the built environment and to ensure the accuracy of key structural attributes.
Automation of control systems is expected to be important in the economic and safe operation of microreactors. Therefore, there is a need to develop and demonstrate automated control for microreactors, along with the development of testbeds for this purpose. This report provides updates on the status of a nonnuclear microreactor automated control system (MACS)—a real-time, hardware-in-the-loop testbed for non-nuclear testing of microreactor control system automation. A real-time hardware-in-the-loop testbed incorporates the realistic dynamics of physical systems into control system development and testing. The collaborative effort between Oak Ridge National Laboratory (ORNL) and Idaho National Laboratory (INL) resulted in the development of a prototypic microreactor plant-level digital twin that includes the reactor and a balance of plant system. Advanced control strategies were incorporated to demonstrate testing of control automation solutions. The gRPC communication protocol, which was implemented in the hardware-in-the-loop testbed by INL, was coupled to a digital twin model developed using the TRANsient Simulation Framework of Reconfigurable Models (TRANSFORM) library in Modelica. This digital twin simulation was tested with the ViBRANT hardware for realistic feedback and visual representation of control action in real time. A modular Python client structure was developed to manage functional mock-up unit-based simulation and real-time gRPC communication. Hardware-in-the-loop testing indicated that the modeled reactor—a natural-convection, molten-salt coolant loop configuration—responds well to control of drum positioning for modulation of reactor core power, as well as system-level control and downstream demand changes. Ongoing research is focused on integrating additional control algorithms that utilize data from newly included sensors within the MACS hardware testbed, as well as demonstrating and assessing the performance of the different automated control algorithms on multiple additional operational scenarios.
As a part of conversion efforts from highly enriched uranium (HEU) to low-enriched uranium (LEU) fuel under direction of the National Nuclear Security Administration of the U.S. Department of Energy, multiple proposed designs of the High Flux Isotope Reactor (HFIR) have been created and assessed regarding reactor physics performance metrics, including designs utilizing uranium silicide dispersion fuel (U3Si2-Al). This report updates the previous analyses that evaluated the nuclear safety performance of LEU fuel designs with respect to selected accident events from the HFIR Safety Analysis Report (SAR). Both the Low Density (LD) and High Density (HD) Optimized designs’ reactivity initiated accident fuel performance improved relative to the HEU fuel, attributed to greater 238 U negative Doppler feedback. However, the thermal margins for primary coolant system accidents were reduced with some acceptance criteria unable to be met. The need to resolve reduced thermal margin, open modeling items, and unresolved assumptions was identified.
This technical basis update focuses on the design life of the SAVY-4000® (hereafter “SAVY”) series of nuclear material storage container (e.g., used to store, transport, and handle special nuclear material outside of a glovebox), previously approved under DOE Manual 441.1-1, Nuclear Material Packaging Manual. The SAVY is approved for storing all authorized contents for a period of 15 years. The lifetime extension technical basis is established on the compiled technical data from the on-going SAVY and Hagan surveillance programs, destructive analysis results, accelerated aging studies, and performance testing, in line with the regulatory rigor of DOE M441.1-1.
This presentation provides an overview of the recent updates to the international standards on radiometry.
The report will cover recent updates and near-term plans of the G4CPT activity
This report summarizes the recent updates of Sandia's computational model for geomechanical analysis of salt caverns at the Bryan Mound site, one of the U.S. Strategic Petroleum Reserves.
The Lahaina Energy Partnership (LEP) is an initiative funded by the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) to support energy planning and rebuilding efforts in Hawaii's historic town of Lahaina on Maui as the community recovers from a devastating fire on August 8, 2023, with technical assistance provided by the National Laboratory of the Rockies. NLR has partnered with Hawaii-based community organizations to engage with Lahaina the community on energy priorities and inform the technical assistance scope. This virtual workshop presentation is the second in a two-part series to provide progress updates and request community input to guide next steps. Workshop 1 on November 18 focused on hydropower resource potential, building energy modeling, and workforce development. Workshop 2 on December 11 (this presentation) will focus on microgrids, electric grid hardening, policy and regulation.
The Lahaina Energy Partnership (LEP) is an initiative funded by the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) to support energy planning and rebuilding efforts in Hawaii's historic town of Lahaina on Maui as the community recovers from a devastating fire on August 8, 2023, with technical assistance provided by the National Laboratory of the Rockies. NLR has partnered with Hawaii-based community organizations to engage with Lahaina the community on energy priorities and inform the technical assistance scope. This virtual workshop presentation is the first in a two-part series to provide progress updates and request community input to guide next steps. Workshop 1 on November 18 (this presentation) will focus on Hydropower resource potential, building energy modeling, workforce development. Workshop 2 on December 11 (presentation forthcoming) will focus on microgrids, electric grid hardening, policy and regulation.
To clarify the current and future landscape for renewable propane (RP) production, this work evaluates the value proposition of recovering RP from existing and planned hydroprocessed esters and fatty acids (HEFA) biorefineries and surveys emerging technologies under development or deployment. HEFA biorefineries co-produce a propane-rich fuel gas stream, normally used to meet HEFA process heat requirements, from which propane can be recovered and sold to create an additional revenue stream alongside liquid transportation fuels such as renewable diesel (RD) and sustainable aviation fuel (SAF). This report updates and extends a 2022 analysis of RP recovery from HEFA facilities by escalating capital and operating costs to 2024 prices, incorporating recent policy developments (including the Section 45Z Clean Fuel Production Credit), evaluating RP recovery for both RD- and SAF-focused HEFA facilities at two scales (3,000 and 75,000 barrels per day of feedstock), and quantifying the impact of RP recovery on HEFA liquid-fuel carbon intensity (CI) and associated tax credits using the 45ZCF-GREET model. For a 3,000 BPD RD-focused HEFA facility, approximately 3.5 million gallons per year (MGPY) of RP can be recovered; in this base case, the estimated payback period is 18 months based on the total installed cost of the RP recovery equipment and 36 months based on the total capital investment for the entire RP recovery project. The payback period is slightly shorter for the analogous SAF-focused configuration (approximately 4.3 MGPY RP). Sensitivity analysis shows that CAPEX magnitude, RP recovery plant scale, and CI-driven tax credit valuations are the dominant determinants of project viability. RP recovery may increase the CI of HEFA liquid fuels, which can reduce liquid-fuel tax credits (a key revenue stream for the HEFA biorefinery) and lengthen payback periods. However, RP recovery generally remains economically favorable across a wide range of plausible scenarios and market conditions. The report also summarizes emerging pathways that could expand future RP supply.
This presentation gives an update on UNIFI 1MW multi-vendor GFM inverter testing. The 1MW demo enters the last stage of the test, which is the integration test. And the main objectives of the integration tests include: 1) explore the interoperability of dispatching a future grid with energy mix (GFM inverters, GFL inverters and synchronous machine). The presentation highlights one example test, ROCOF, and summarizes all the key learning.
This report presents an updated “harmonization study” documenting the collaborative analysis of saline microalgae cultivation and conversion to fuels and products. Four national laboratory modeling teams reconvened to investigate the resource, economic, and environmental sustainability implications of integrated systems encompassing large-scale algae farms and conversion biorefineries. Relative to prior harmonization analyses conducted by these partners, the present effort focuses on more near-term technology potential based on the use of nutrient-replete, high-protein algal biomass compositions (more readily achievable today without sacrificing cultivation productivity) coupled with individual algae farms varying in size but generally smaller at 3,900 acres on average (more realistic in practice than a fixed 5,000-acre farm scale previously considered). Additionally, the present assessment adds further granularity around carbon dioxide (CO 2 ) sourcing and transport via carbon capture of nearby point sources, as well as handling of high-saline cultivation media and resultant blowdown/disposal processing. Finally, this assessment focuses on conversion opportunities to produce both fuel (prioritizing sustainable aviation fuel [SAF], in this case via hydrothermal liquefaction) and protein products for the food and feed markets, recognizing growing needs for such products.