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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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During the first quarter of FY20, efforts focused on calibrating a computational model using experimental data. The experimental creep data obtain from specimens containing weld metal exhibit considerable inherent variability making calibration of the computational difficult and may not result in an accurate model.
The Advanced Reactor Technologies Graphite Research and Development Program is conducting an extensive graphite irradiation experiment to provide data for licensing of a high temperature reactor (HTR) design. In past applications, graphite has been used effectively as a structural and moderator material in both research and commercial high temperature gas cooled reactor designs. , Nuclear graphite H 451, used previously in the United States for nuclear reactor graphite components, is no longer available. New nuclear graphite grades have been developed and are considered suitable candidates for new HTR reactor designs. To support the design and licensing of HTR core components within a commercial reactor, a complete irradiated properties database must be developed for these current grades of graphite. Quantitative data on in service material performance are required for the physical, mechanical, and thermal properties of each graphite grade, with a specific emphasis on data accounting for the life limiting effects of irradiation creep on key physical properties of the HTR candidate graphite grades. Further details on the research and development activities and associated rationale required to qualify nuclear grade graphite for use within the HTR are documented in the graphite technology research and development plan.
This manuscript describes an ongoing NEAMS effort to better determine the performance of advanced nuclear fuels, in particular the creep behavior of doped UO$_2$ for light water reactors. In our previous work, we outlined a method to utilize data generated from lower length scale simulations and implement it into the engineering scale fuel performance analysis. This process has been further refined, and in addition, new data has been used to train the surrogate model which has also been substantially improved since the previous iteration. The new model is compared against the current empirical model used in BISON using both scoping calculations to define the performance over the parameter space and using integral instrumented fuel assessment cases to determine the impact of these models on the overall fuel performance. Suggestions and guidance for future improvements to this method are provided to ensure the model covers relevant parameter space and phenomena.
Presentation at TMS 2026 on machine learning modeling of creep rupture behavior in 9-12% Cr ferritic-martensitic steels using a stacked approach.
The evaporation of capillary bridges is experimentally investigated at the microscale through a three-grain capillary cluster. This setting provides the minimum viable description of Haines jumps during evaporation, that is, capillary instabilities stemming from air entry into a saturated granular material. The displacement profile of a meniscus is obtained via digital image correlation for different grain materials, geometries, and separations. While it is well known that Haines jumps are triggered at the pore throat, we find that these instabilities are of three types depending on the separation. We also provide a temporal characterization of Haines jumps; we find that they are accurately described, as tertiary creep instabilities, by Voight’s relation, similarly to landslides and volcanic eruptions. This finding extends the description of capillary instabilities beyond their onset predicted by Laplace equilibrium. Our contribution also paves the way for a microscopically-informed description of desiccation cracks, of which Haines jumps are the precursors.
Creep of a recrystallized aluminum sap-type alloy
Creep buckling of spherical shells
Exposure of nickel-base alloys to overtemperature indicates that their creep resistance is sensitive to particle size and spacing in their microstructure
Creep testing data and machine reliability for high-temperature long-time tests on niobium, tungsten, and rhenium alloys
Onset of creep stress measured for metallic materials subjected to constant loads at elevated temperatures - tension testing
Ultrahigh vacuum creep data for tungsten, tungsten-25 per cent rhenium, TZM and TZC MOLYBDENUM alloys and AS-30 niobium alloy
High temperature creep analysis of niobium alloy
Creep resistance of refractory alloys at elevated temperatures under ultrahigh vacuum conditions
Zinc-base alloy creep resistance and structure in extruded wire prepared by powder metallurgy
Creep data obtained at high temperatures for molybdenum, niobium, tantalum, and tungsten refractory alloys which have potential use in advanced power systems
Interfaces between fatigue, creep, and fracture
Creep tests on polycrystalline copper with surface reoxidized or cleaned by argon bombardment at elevated temperatures and high vacuum