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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 1,279 records · Page 71
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Test based reliability assessment method for a safety critical software in reactor protection system - 284

Digitalization of the instrumentation and control systems in nuclear power plant entails some new features which do not exist in analog systems. When the new features are applied in safety critical systems, the risk stemming from them should be quantified properly to assure the reliability of the entire power plant. Among the new features, software is considered as the most important factor because it can cause common cause failure to many redundant systems. Therefore, in this work, a test based reliability assessment method for a safety-critical software is developed. An output of a software is determined by not only inputs but also the internal state of the software at the time. In the case of safety critical software developed for usage in nuclear power plant, it is possible to directly investigate probable internal states thanks to detailed design specification and programing features, and the probable inputs also can be identified based on the physical linearity of each process parameter and hardware characteristics related to data acquisition. In this work, a development method for practical exhaustive test case consisting of investigation of internal state and probable input sets to a specific internal state are suggested. In addition to this, software logic simulator for execution of software logic test and the reliability quantification method based on the test result are developed. The feasibility of the suggested method is demonstrated via a case study. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

ECAR-7365 Rev 0 MARVEL Over Pressure Protection Report

This ECAR encompasses and documents compliance to the pressure safety requirements of the Microreactor Applications Research Validation and Evaluation (MARVEL) Reactor Primary Coolant Boundary (referred to herein as the Primary Coolant System, or PCS, which includes the outer boundary of the Central Insurance Absorber (CIA)) as a Class A system (equivalent to a Section III Division 1 Class 1 system) for high temperature reactors subjected to elevated temperature service.

21 - SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLAN↗
DOE OSTI2021

A Study of Model-Based Protective Fast-Charging and Associated Degradation in Commercial Smartphone Cells: Insights on Cathode Degradation as a Result of Lithium Depositions on the Anode

The ever expanding mobile consumer electronic market has accelerated the need for safe and efficient fast-charging approaches that improve the overall speed of battery charging without hastened deterioration of the battery performance. Herein, the impact of a resource inexpensive, physics-based, electrochemically optimized fast-charging algorithm (charging time < 2 h) for mobile devices is investigated. A critical difference in the amount and morphology of lithium deposits on the anode for cells fast-charged without an optimized algorithm is observed and found to be the main cause of capacity decay. Furthermore, an in-depth study of the LiCoO 2 cathode regions opposite to pronounced lithium deposits on the anode reveals a “mirroring” phenomenon, i.e., a frozen monoclinic phase, and inactivity to relithiation. In operando hard X-ray absorption spectroscopy reveals that degraded spots on harvested cathodes seem to be activated again and participate in the intercalation process when lithiated at low rates from lithium foil counter electrodes. On the other hand, tests at higher C-rates, closer to the actual fast-charging rate, reveal only negligible oxidation state changes and therefore poor performance.

25 ENERGY STORAGE↗
DOE OSTI2022

Covalent Organic Framework as an Efficient Protection Layer for a Stable Lithium‐Metal Anode

Abstract Lithium (Li) metal shows great potential for achieving high‐energy‐density rechargeable batteries. However, the practical applications of Li‐metal batteries are still challenged by the formation of Li dendrites and unstable solid‐electrolyte interphase (SEI) on metallic Li. Herein, a thin covalent organic framework layer is in situ fabricated on Li (COF‐Li) to suppress Li dendrite growth and mitigate the side reaction on the Li anode. The COF has a periodic and uniform porosity, allowing for selectively sieving Li ions and guiding a uniform Li deposition. As a result, the COF‐Li exhibits a non‐dendrite morphology during repeated Li plating/stripping and demonstrates a remarkable cycle life over 13 200 h with an extremely low overpotential of only 16 mV at a high current density of 10 mA cm −2 and a high areal capacity of 10 mAh cm −2 .

He, Jiarui↗
DOE OSTI2022

Covalent Organic Framework as an Efficient Protection Layer for a Stable Lithium-Metal Anode

We report Lithium (Li) metal shows great potential for achieving high-energy-density rechargeable batteries. However, the practical applications of Li-metal batteries are still challenged by the formation of Li dendrites and unstable solid-electrolyte interphase (SEI) on metallic Li. Herein, a thin covalent organic framework layer is in situ fabricated on Li (COF-Li) to suppress Li dendrite growth and mitigate the side reaction on the Li anode. The COF has a periodic and uniform porosity, allowing for selectively sieving Li ions and guiding a uniform Li deposition. As a result, the COF-Li exhibits a non-dendrite morphology during repeated Li plating/stripping and demonstrates a remarkable cycle life over 13 200 h with an extremely low overpotential of only 16 mV at a high current density of 10 mA cm -2 and a high areal capacity of 10 mAh cm -2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Surface Protected Organozirconium Catalyzes C─H Alumination of Saturated Hydrocarbons

Surface grafted organozirconium catalyzes C─H/Et─Al exchange reactions, involving saturated hydrocarbons and AlEt 3 , to afford organoaluminum compounds and ethane. The Zr(O t Bu) 3 @SiO 2 -Al 2 O 3 –700 (1) catalyst contains monopodal ≡SiO─Zr(O t Bu) 3 and only a few residual silanols (<5%). Nonetheless, these silanols are the Achille's heel of 1, providing a pathway for surface and catalyst degradation during catalysis, limiting the alkylaluminum yield and catalyst turnover. Support degradation, involving the cleavage of Si─O bonds by activated surface organometallics, is inhibited by capping silanols with ─SiMe 3 . Residual silanols in 1 react with allyltrimethylsilane, as determined by solid-state 13 C and 29 Si nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, and reaction stoichiometry, to form Zr(O t Bu) 3 /SiMe 3 @SiO 2 -Al 2 O 3–700 (2), which is resistant to degradation by AlEt 3 . C─H alumination of dodecane catalyzed by 2 produces higher yields of the 1-dodecylaluminum product in comparison to 1, and in >95% selectivity. Additionally, methane undergoes 2-catalyzed C─H alumination, providing a route to AlMe 3 .

Banerjee, Sayak [Iowa State Univ., Ames, IA (Unite↗
DOE OSTI2020

Systems Theory Principles and Complex Systems Engineering Concepts for Protection and Resilience in Critical Infrastructure: Lessons from the Nuclear Sector

Part of the Presidential Policy Directive 21 (PPD-21) (PPD 2013) mandate includes evaluating safety, security, and safeguards (or nonproliferation) mechanisms traditionally implemented within the nuclear reactors, materials, and waste sector of critical infrastructure—including a complex, dynamic set of risks and threats within an all-hazards approach. In response, research out of Sandia National Laboratories (Sandia) explores the ability of systems theory principles (hierarchy and emergence) and complex systems engineering concepts (multidomain interdependence) to better understand and address these risks and threats. Herein, this Sandia research explores the safety, safeguards, and security risks of three different nuclear sector-related activities—spent nuclear fuel transportation, small modular reactors, and portable nuclear power reactors—to investigate the complex and dynamic risk related to the PPD-21-mandated all-hazards approach. This research showed that a systems-theoretic approach can better identify inter-dependencies, conflicts, gaps, and leverage points across traditional safety, security, and safeguards hazard mitigation strategies in the nuclear reactors, materials, and waste sector. Resulting from this, mitigation strategies from applying systems theoretic principles and complex systems engineering concepts can be (1) designed to better capture interdependencies, (2) implemented to better align with real-world operational uncertainties, and (3) evaluated as a systems-level whole to better identify, characterize, and manage PPD-21's all hazards strategies.

42 ENGINEERING↗
DOE OSTI2021

Long‐term drench of exopolysaccharide from Leuconostoc pseudomesenteroides XG5 protects against type 1 diabetes of NOD mice via stimulating GLP ‐1 secretion

Abstract BACKGROUND Type 1 diabetes is an autoimmune disease that results in the specific destruction of insulin‐producing beta cells in the pancreas. The aim of this study was to investigate the mechanism of exopolysaccharide from Leuconostoc pseudomesenteroides XG5 (XG5 EPS) against type 1 diabetes. RESULTS Long‐term drench of XG5 EPS delayed the onset of autoimmune diabetes and had fewer islets with high‐grade infiltration (an insulitis score of 3 or 4) than untreated NOD mice. Oral administration of 50 mg kg −1 d −1 XG5 EPS increased the insulin and glucagon‐like peptide‐1 (GLP‐1) levels of serum, stimulated GLP‐1 secretion and upregulated gcg mRNA expression of colon in NOD mice. Moreover, oral administration of 50 mg kg −1 d −1 XG5 EPS significantly increased total short‐chain fatty acids levels in the colon contents, especially those of acetic acid and butyric acid. In NCI‐H716 cells, 500 and 1000 μmol L −1 sodium butyrate promoted the secretion of GLP‐1 and upregulated the mRNA expression of gcg and PC3 , while XG5 EPS and sodium acetate did not stimulate the GLP‐1 secretion. Therefore, long‐term drench of XG5 EPS delayed the onset of autoimmune diabetes, which may be directly correlated with the increase of butyrate in the colon of NOD mice. CONCLUSION Long‐term drench of 50 mg kg −1 d −1 XG5 EPS promoted the expression and secretion of GLP‐1 by increasing the production of butyric acid, thereby delaying T1D onset in NOD mice. © 2021 Society of Chemical Industry.

Pan, Lei↗