Search NASA⌕ Search

SEARCH · Search NASA

Results for “certification”

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.

At least 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Increasing the detection sensitivity of the Radionuclide Aerosol Sampler/Analyzer using a cosmic veto system

Different configurations of a cosmic veto system have been evaluated for the Radionuclide Aerosol Sampler/Analyzer (RASA). The upgrade has the potential to resolve the issue that U.S. IMS radionuclide stations have difficulty meeting the 140Ba Minimum Detectable Concentration (MDC) certification requirement when the natural background radioactivity is high. It also aims to improve the detection sensitivity of the RASA system for other fission and activation products indicative of a nuclear explosion. This proof of principal utilizes a prototype RASA system located at Pacific Northwest National Laboratory (PNNL), and has demonstrated background reductions by up to 11.3% and improvements in the average MDC by up to 7.7%. Recommendations are made for either a 1 or 3 plate configuration, which improves the 140Ba MDC by 5.6% and 7.2% for a blank filter. Whilst elevated 212Pb activity remains problematic, the cosmic veto system provides a practical solution for sensitivity improvement with little design modification of the RASA. It also has value in improving sensitivity and preventing false-positives at remote U.S. IMS station locations where sample transfer for laboratory analysis is logistically difficult.

Comprehensive Nuclear-Test-Ban Treaty, RASA, Cosmi↗
DOE OSTI2017

Modification of MELCOR for severe accident analysis of candidate accident tolerant cladding materials

A number of materials are currently under development as candidate accident tolerant fuel and cladding for application in the current fleet of commercial light water reactors (LWRs). The safe, reliable and economic operation of the nation’s nuclear power reactor fleet has always been a top priority for the nuclear industry. Continual improvement of technology, including advanced materials and nuclear fuels, remains central to the industry’s success. Enhancing the accident tolerance of light water reactors became a topic of serious discussion following the 2011 Great East Japan Earthquake, resulting tsunami, and subsequent damage to the Fukushima Daiichi nuclear power plant complex. The overall goal for the development of accident tolerant fuel (ATF) systems for LWRs is to identify alternative fuel system technologies to further enhance the safety, competitiveness, and economics of commercial nuclear power. Designed for use in the current fleet of commercial LWRs, or in reactor concepts with design certifications (GEN-III+), to achieve their goal enhanced ATF must endure loss of active cooling in the reactor core for a considerably longer period of time than the current fuel system, while maintaining or improving performance during normal operation. Many available nuclear fuel performance analysis tools are specifically developed for the current UO 2 – Zirconium alloy fuel system. The MELCOR severe-accident analysis code, under development at the Sandia National Laboratory in New Mexico (SNL-NM) for the US Nuclear Regulatory Commission (NRC), is one of these tools. This article describes modifications made to a version of the MELCOR code by the Idaho National Laboratory (INL) that allows its application to alternate fuel-cladding systems. Preliminary analysis results are presented in this paper for candidate silicon carbide and FeCrAl cladding concepts.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Integrating quantitative defense-in-depth metrics into new reactor designs

Risk-informed, performance-based (RIPB) methods have progressed to the point where high-level guidance can be used to augment traditional, deterministic, nuclear safety design practices in areas important to nuclear reactor safety. This paper describes an approach for augmenting the traditional defense-in-depth (DID) qualitative approach with quantitative risk information from a plant-specific probabilistic risk assessment (PRA) in a way that is structured, can be applied on a consistent basis, and allows for clear acceptance criteria. Adding performance-based targets that should be achieved is expected to result in safer and more economical plant designs. Evaluations of DID can be conducted throughout the design process as well as in support of design certification and operating license applications to identify where defense protections could be enhanced or relaxed. Consistent with the United States Nuclear Regulatory Commission's policy statement encouraging greater use of PRA to improve safety decision making and regulatory efficiency, this scenario-based DID method can be used to evaluate changes and overall plant design as part of the normal design control process. Although the RIPB method presented in this paper was developed for application to advanced passive light water reactor designs, the metrics could be tailored to other reactor designs. This risk-informed approach to DID helps to ensure that public and worker risk insights are integrated into the design process holistically.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

Process and environmental safety of thermochemical conversion of biomass

Biomass presents a promising opportunity for converting waste into valuable energy, fuels, and chemicals through various thermochemical processes, including hydrothermal carbonization, hydrothermal liquefaction, pyrolysis, gasification, and combustion. However, these processes operate under extreme conditions, introducing significant safety hazards that necessitate meticulous management to prevent accidents. This review discusses potential hazards, risk mitigation strategies, and safety management practices, emphasizing the importance of integrated safety measures into the design and operation of these processes. It also highlights the critical need for robust safety engineering and environmental management strategies tailored to each thermo-chemical process. As these processes transition from laboratory to industrial scale, there is an imperative to develop a clear and concise pathway for emerging industries to achieve regulatory compliance, achieve safety certification, and enable effective stewardship of potential fugitive emissions. By addressing safety and environmental concerns, stakeholders can optimize economic benefits, rural development, and achieve sustained domestic energy generation benefits offered by biomass conversion technologies. Further research on plant design optimization, operational safety, environmental evaluation standardization, and innovative waste management solutions will support the safe and effective scaling of these technologies, ultimately contributing to sustainable management and resource recovery.

09 - BIOMASS FUELS↗
DOE OSTI2017

Residential green power demand in the United States

This paper investigates the demand determinants of green power in the U.S. residential sector. The data employed were collected by the National Renewable Energy Laboratory and consist of a cross-section of seven utilities observed over 13 years. A series of tests are performed that resulted in estimating a demand equation using the one-way cross-section random effects model. As expected, we find that demand is highly price inelastic. More interestingly though, is that elasticity with respect to number of customers is 0.52 leading to the conclusion that new subscribers tend to purchase less green power on average than the existing customers. Another compelling finding is that obtaining accreditation will have a 28.5% positive impact on consumption. Knowing that gaining green accreditation is important to the success of programs, utilities may want to seek certification and highlight it in their advertising campaigns.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2025

A comprehensive academic and industrial survey of blockchain technology for the energy sector using fuzzy Einstein decision-making

The global energy sector is undergoing a significant transformation driven by decarbonization and digitalization, leading to the emergence of Distributed Ledger Technology (DLT) — particularly blockchain — as a promising tool for enhancing transparency, security, and efficiency in modern power systems. This study aims to provide a comprehensive academic and industrial survey of blockchain applications in the energy sector and develop a robust decision-making framework to identify and prioritize the most promising real-world use cases based on multidisciplinary criteria. A three-stage methodology was adopted: (i) a literature and market review encompassing over 300 academic publications and commercial blockchain initiatives in energy, (ii) an in-depth evaluation of the evolution and viability of blockchain initiatives in energy with the help of expert surveys, and (iii) a novel decision-making model using a q-rung orthopair fuzzy Multi-Attributive Border Approximation (q-ROF-MABAC) method under the Einstein operator. The results were compared with existing decision models to validate consistency and robustness. Nine key blockchain use case categories were identified and ranked based on technical, economic, and governance dimensions. The results demonstrated that integrating expert insights into a fuzzy logic framework helps filter out overhyped claims in the literature and prioritize realistic and high-impact applications such as green certificates, grid services, and peer-to-peer energy trading. The model’s rankings remained stable across varying weight configurations, confirming the robustness of the methodology. This study provides an evidence-based decision-support tool for researchers, industry stakeholders, and policymakers to better understand, evaluate, and adopt blockchain technologies in the energy sector.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2017

Modeling the direct sun component in buildings using matrix algebraic approaches: Methods and validation

Simulation tools that enable annual energy performance analysis of optically-complex fenestration systems have been widely adopted by the building industry for use in building design, code development, and the development of rating and certification programs for commercially-available shading and daylighting products. The tools rely on a three-phase matrix operation to compute solar heat gains, using as input low-resolution bidirectional scattering distribution function (BSDF) data (10–15° angular resolution; BSDF data define the angle-dependent behavior of light-scattering materials and systems). Measurement standards and product libraries for BSDF data are undergoing development to support solar heat gain calculations. Simulation of other metrics such as discomfort glare, annual solar exposure, and potentially thermal discomfort, however, require algorithms and BSDF input data that more accurately model the spatial distribution of transmitted and reflected irradiance or illuminance from the sun (0.5° resolution). This study describes such algorithms and input data, then validates the tools (i.e., an interpolation tool for measured BSDF data and the five-phase method) through comparisons with ray-tracing simulations and field monitored data from a full-scale testbed. Simulations of daylight-redirecting films, a micro-louvered screen, and venetian blinds using variable resolution, tensor tree BSDF input data derived from interpolated scanning goniophotometer measurements were shown to agree with field monitored data to within 20% for greater than 75% of the measurement period for illuminance-based performance parameters. The three-phase method delivered significantly less accurate results. We discuss the ramifications of these findings on industry and provide recommendations to increase end user awareness of the current limitations of existing software tools and BSDF product libraries.

14 SOLAR ENERGY↗
DOE OSTI2018

Proposal and evaluation of subordinate standard solar irradiance spectra for applications in solar energy systems

Reference solar irradiance spectra are needed to specify key parameters of solar technologies such as photovoltaic cell efficiency, in a comparable way. The IEC 60904-3 and ASTM G173 standards present such spectra for Direct Normal Irradiance (DNI) and Global Tilted Irradiance (GTI) on a 37 degrees tilted sun-facing surface for one set of clear-sky conditions with an air mass of 1.5 and low aerosol content. The IEC/G173 standard spectra are the widely accepted references for these purposes. Hence, the authors support the future replacement of the outdated ISO 9845 spectra with the IEC spectra within the ongoing update of this ISO standard. The use of a single reference spectrum per component of irradiance is important for clarity when comparing and rating solar devices such as PV cells. However, at some locations the average spectra can differ strongly from those defined in the IEC/G173 standards due to widely different atmospheric conditions and collector tilt angles. Therefore, additional subordinate standard spectra for other atmospheric conditions and tilt angles are of interest for a rough comparison of product performance under representative field conditions, in addition to using the main standard spectrum for product certification under standard test conditions. This simplifies the product selection for solar power systems when a fully-detailed performance analysis is not feasible (e.g. small installations). Also, the effort for a detailed yield analyses can be reduced by decreasing the number of initial product options. After appropriate testing, this contribution suggests a number of additional spectra related to eight sets of atmospheric conditions and tilt angles that are currently considered within ASTM and ISO working groups. The additional spectra, called subordinate standard spectra, are motivated by significant spectral mismatches compared to the IEC/G173 spectra (up to 6.5%, for PV at 37 degrees tilt and 10-15% for CPV). These mismatches correspond to potential accuracy improvements for a quick estimation of the average efficiency by applying the appropriate subordinate standard spectrum instead of the IEC/G173 spectra. The applicability of these spectra for PV performance analyses is confirmed at five test sites, for which subordinate spectra could be intuitively selected based on the average atmospheric aerosol optical depth (AOD) and precipitable water vapor at those locations. The development of subordinate standard spectra for DNI and concentrating solar power (CSP) and concentrating PV (CPV) is also considered. However, it is found that many more sets of atmospheric conditions would be required to allow the intuitive selection of DNI spectra for the five test sites, due in particular to the stronger effect of AOD on DNI compared to GTI. In conclusion, the matrix of subordinate GTI spectra described in this paper are recommended to appear as an option in the annex of future standards, in addition to the obligatory use of the main spectrum from the ASTM G173 and IEC 60904 standards.

14 SOLAR ENERGY↗
DOE OSTI2021

Characterization of commercial vehicles’ start-up operations from in-use data

Diesel engines produce disproportionate levels of emissions when the engine and after-treatment systems are operating at low temperatures. This situation arises most commonly when the vehicle is first started after overnight. To quantify emissions attributable to vehicle starts, a sizable collection of on-road commercial vehicle operating data is analyzed to identify start-up events and inspect associated emissions. Data was obtained from the National Renewable Energy Laboratory’s (NREL’s) Fleet DNA and from the Center for Environmental Research & Technology (CE-CERT). Included are 500 + diesel vehicles with more than 42,000 recorded days, drawn from 25 vocational categories across the United States. Analysis shows that vehicle behavior, in terms of engine cold- and warm-operation, starts per day, soak time, and warm-up duration, differs significantly between vehicle vocations. Also, weighting factors for cold- and hot-starts currently used in the U.S. Environmental Protection Agency’s Federal Test Procedure (FTP) for heavy-duty emissions certification accurately represent real-world operations. Although the FTP includes a comparable fraction of cold operation, the hot fraction is much shorter than real-world operation due to limited test duration. The investigation also revealed that real-world engines operate for a significant amount of time when the engine coolant is in the “hot-stabilized” region, but the selective catalytic reduction (SCR) temperature is below its effective operating temperature of 200 °C. Of the vehicles under investigation, almost 20% of their operational time is within this condition. Therefore, novel approaches to raise and maintain SCR temperature are highly required to further reduce engine emissions.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2021

Lifetime risk of suicide among survivors of the atomic bombings of Japan

Abstract Aims The long-term physical health effects of the atomic bombings of Hiroshima and Nagasaki are well characterised, but the psychological effects remain unclear. Therefore, we sought to determine whether measures of exposure severity, as indirect measures of psychological trauma arising from exposure to the atomic bombings, are associated with suicide mortality among atomic bomb survivors. Methods The Life Span Study is a prospective cohort study of 93 741 Japanese atomic bomb survivors who were located within 10 km of the hypocentre in Hiroshima or Nagasaki at the time of the bombings in 1945, and 26 579 residents of Hiroshima and Nagasaki who were not in either city at the time of the bombings, matched to survivors on city, sex and age. Measures of exposure severity included: proximity to the hypocentre, type of shielding between the survivor and the blast and self-reported occurrence of acute radiation and thermal injuries. Date of death was obtained from the Japanese National Family Registry system. Cause of death was obtained from death certificates. Adjusted hazard ratios (HRs) were estimated from Cox regression models overall and stratified by sex and age. Results During the 60-year follow-up period (1950–2009), 1150 suicide deaths were recorded among 120 231 participants (23.6 per 100 000 person-years): 510 among 70 092 women (17.2 per 100 000 person-years) and 640 among 50 139 men (33.6 per 100 000 person-years). Overall, there was no association of proximity, type of shielding or the occurrence of acute injuries with suicide mortality. Among those <25 years of age at the time of the bombings, increased suicide risk was observed for survivors outside v . shielded inside any structure (HR: 1.24; 95% confidence interval (CI): 1.03, 1.48; interaction p = 0.054) and for those who reported flash burns (HR: 1.32; 95% CI: 1.00, 1.73; interaction p = 0.025). Sex-stratified analyses indicated that these associations were limited to men. Among women, closer proximity to the hypocentre was associated with a non-significant increase in suicide risk, with a positive association between proximity and suicide risk observed among women <15 years of age (HR: 1.09 per km; 95% CI: 1.00, 1.18; interaction p = 0.067). Conclusions Proximity to the hypocentre, shielding and acute injury presence do not generally appear to influence suicide mortality among atomic bomb survivors. However, heterogeneity may exist by age and sex, with younger survivors potentially more sensitive to psychological trauma. Coupled with other studies, our results suggest the importance of long-term monitoring of mental health among young populations exposed to catastrophic events or mass trauma.

Psychiatry↗
DOE OSTI2015

Diesel Fuel Property Effects on In-Cylinder Liquid Penetration Length: Impact on Smoke Emissions and Equivalence Ratio Estimates at the Flame Lift-Off Length

Here in this study, elastic scattering was employed to investigate diesel fuel property effects on the liquid length (i.e., the maximum extent of in-cylinder liquid-phase fuel penetration) using select research fuels: an ultralow-sulfur #2 diesel emissions-certification fuel (CF) and four of the Coordinating Research Council (CRC) Fuels for Advanced Combustion Engines (FACE) diesel fuels (F1, F2, F6, and F8). The experiments were performed in a single-cylinder heavy-duty optical compression-ignition engine under time-varying, noncombusting conditions to minimize the influence of chemical heat release on the liquid-length measurement. The FACE diesel fuel and CF liquid lengths under combusting conditions were also predicted using Siebers’ scaling law and pressure data from previous work using the same fuels at similar in-cylinder conditions. The objective was to observe if the liquid length under noncombusting or combusting conditions provides additional insights into the relationships among the main fuel properties (i.e., cetane number (CN), the 90 vol % distillation recovery temperature (T90), and aromatic content) and smoke emissions. Results suggest that liquid-length values are best correlated to fuel distillation characteristics measured with ASTM D2887 (simulated distillation method). This work also studied the relationship between liquid length and lift-off length, H (i.e., distance from the fuel-injector orifice exit to the position where the standing premixed autoignition zone stabilizes during mixing-controlled combustion). Two possible cases were identified based on the relative magnitudes of liquid length under combusting conditions (Lc) and H. The low-CN fuels are representative of the first case, L c < H, in which the fuel is always fully vaporized at H. The high-CN fuels are mostly representative of the second case, L c ≥ H, in which there is still liquid fuel at H. Lc ≥ H would suggest higher smoke emissions, but there is not enough evidence in this work to support a compounding effect of a longer liquid length on top of the aromatic-content effect on smoke emissions for fuels with similar CN, supporting previous findings in the literature that lift-off length plays a more important role than liquid-length on diesel combustion. At the same time, the experimental results suggest a decrease in the fuel-jet spreading angle, i.e., a decrease in the entrainment rate into the jet at and downstream of H, under combusting conditions, that is not accounted for in the model used to predict the values of $\phi$(H). Lastly, as a result, L c may be of interest for accurate predictions of $\phi$(H), especially for combustion strategies designed to lower in-cylinder soot by operating near or below the nonsooting $\phi$(H)-value (i.e., $\phi$(H) ≈ 2).

02 PETROLEUM↗
DOE OSTI2024

Ceramic–Metal (Cermet) Composites: A Review of Key Properties and Synthesis Methods Focused on Nuclear Waste Immobilization

Here this paper reviews key properties, applications, and examples of ceramic-metal composites (cermets), and metal matrix composites (MMC) with emphasis on their applicability as waste forms for immobilizing nuclear waste. While the literature is mature for vitrified and cementitious radioactive waste forms, cermet materials have not received adequate attention as potential candidates for immobilizing nuclear waste. To promulgate this effort, this review connects cermet and MMC design, such as hardened tools, with the chemistry of radioactive waste streams. A discussion on certification and qualification standards for cermet waste forms, literature gaps, and “how-to” sections on cermet processing techniques. Key parameters discussed include thermal conductivity, chemical durability, and waste loading, as well as examples for metal-containing waste forms. As cermet waste forms gain momentum within the community, this review paper aims ensure the end-of-life nuclear fuel cycle is addressed from a materials and waste disposition perspective.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Effect of Thermal Storage on the Emissions and Efficiency Performance of a Wood Pellet-Fired Residential Boiler

Wood pellet boilers for residential heating applications offer the promise of low emissions, high efficiency, and automatic operation. However, when operated in the field, these units operate often at very low loads causing them to cycle. In this study, the performance of a 25-kW modern pellet boiler under emulated field conditions and fixed nominal loads of 15% and 100% has been studied in a lab—with and without a buffer tank. A dilution tunnel approach was used for the measurement of particulate emissions, in accordance with U.S. certification testing requirements under EPA Methods 28 WHH and 28 WHH PTS. Results show that increasing the amount of thermal storage used decreases cycling rates leading to decreased emissions and increased efficiency. Without thermal storage, integrated efficiency over a 15% load test period was 57%, compared to 74% when thermal storage was used. Particulate emissions were 180 mg/MJ and 64 mg/MJ for the 15% load case without and with thermal storage, respectively.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2014

Investigation of methyl decanoate combustion in an optical direct-injection diesel engine

In this study, an optically accessible heavy-duty diesel engine was used to investigate the impact of methyl decanoate (MD) on combustion and emissions. A specific goal of the study was to determine if MD could enable soot-free leaner-lifted flame combustion (LLFC) – a mode of mixing-controlled combustion associated with fuel-air equivalence ratios below approximately two. An ultra-low sulfur diesel certification fuel (CF) was used as the baseline fuel, and experiments were conducted at two fuel-injection pressures with three levels of charge-gas dilution. In addition to conventional pressure-based and engine-out emissions measurements, exhaust laser-induced incandescence, in-cylinder natural luminosity (NL), and in-cylinder chemiluminescence (CL) diagnostics were used to provide detailed insight into combustion processes.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2026

Who is benefiting from the dramatic decline in U.S. cancer mortality? Place-based evidence of disparities in rates of improvement

After decades of increasing cancer mortality, U.S. rates declined from 1991 to 2019, a 32% decrease. we investigated rates of cancer mortality improvement across 2954 counties and selected characteristics associated with mortality improvements. Data was 21,381,009 county-level neoplasm deaths gleaned from death certificates via CDC WONDER. Analytical techniques included GIS and Moran’s I, OLS, GWR models, and trend comparisons. Counties with the greatest improvement (reduction) in cancer mortality tended to be coastal, higher-income, metropolitan locations. OLS model (R 2 = 0.65) indicated that greatest improvements were observed in counties with higher initial mortality ($\beta =.32$) closely followed by percent urban ($\beta =.31$) and median household income ($\beta =.16$). Whereas percent Black residents ($\beta =-.06$), and percent with education beyond high school ($\beta =-.10$) was less associated on outcomes. Highest income counties were the first to experience improvement in cancer mortality, the highest rates of mortality decline, and the greatest reduction in excess deaths. Even though there was significant improvement in cancer mortality nationally, there were variations in the degree of improvement linked to county location, income, and urbanisation. These results underlie the need to expand place-based initiatives designed to advance cancer health and more equitable improvements in cancer mortality outcomes.

developing world↗
DOE OSTI2024

Critical role of slags in pitting corrosion of additively manufactured stainless steel in simulated seawater

Abstract Pitting corrosion in seawater is one of the most difficult forms of corrosion to identify and control. A workhorse material for marine applications, 316L stainless steel (316L SS) is known to balance resistance to pitting with good mechanical properties. The advent of additive manufacturing (AM), particularly laser powder bed fusion (LPBF), has prompted numerous microstructural and mechanical investigations of LPBF 316L SS; however, the origins of pitting corrosion on as-built surfaces is unknown, despite their utmost importance for certification of LPBF 316L SS prior to fielding. Here, we show that Mn-rich silicate slags are responsible for pitting of the as-built LPBF material in sodium chloride due to their introduction of deleterious defects such as cracks or surface oxide heterogeneities. In addition, we explain how slags are formed in the liquid metal and deposited at the as-built surfaces using high-fidelity melt pool simulations. Our work uncovers how LPBF changes surface oxides due to rapid solidification and high-temperature oxidation, leading to fundamentally different pitting corrosion mechanisms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Evolution of dislocations during the rapid solidification in additive manufacturing

Materials processed by fusion-based additive manufacturing (AM) typically exhibit relatively high dislocation densities, along with cellular structures and elemental segregation. This representative structural feature significantly influences material performance; however, post-mortem microstructure characterizations of AM materials cannot capture the dynamic evolution of dislocations during the manufacturing process, thereby offering limited mechanism-based guidance for further advancing AM techniques and facilitating the qualification and certification of AM products. In this study, we conduct operando high-energy synchrotron X-ray diffraction experiments on wire-laser directed energy deposition of 316 L stainless steel. Through a unique configuration, our operando synchrotron experiments semi-quantitatively probe the dislocation density in solid phases and their dynamic changes during solidification and subsequent cooling. By integrating this advanced synchrotron technique with multi-physics simulation, in-situ neutron diffraction, and multi-scale electron microscopy characterization, our mechanistic study aims to elucidate the effects of rapid cooling and subsequent thermal cycling on the dislocation generation and evolution.

36 MATERIALS SCIENCE↗