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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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Nitrogen injection effects on boundary layer of graphite surface in high-temperature dissociated airflow
Experimental investigation to evaluate high temperature performance and self-generating protective oxide coating of three JT graphite composites
Catalytic effect of impurities on oxidation rate for selected artificial graphites
Equilibrium carbon monoxide pressures measured by torsion effusion studies of reaction of graphite with hafnium and uranium dioxides at high temperatures
Far UV extinction curve and wavelength dependence of interstellar polarization by graphite grains
Pulsed laser techniques for measuring thermal diffusivity of graphites and chars between 500 and 5000 degrees F
Graphite thermochemical response tested in simulated environment for use as thermal shield for hypersonic reentry vehicles
Low dose reactor irradiation effect on temperature dependence of dynamic modulus and internal friction of as-deposited pyrolytic graphite
Boron and graphite filament-resin composites tensile and interlaminar shear strengths and Al foil liner cyclic life in cryogenic pressure vessel tests
Space radiation transport models clearly show that low atomic weight materials provide a better shielding protection for interplanetary human missions than high atomic weight materials. These model studies have concentrated on shielding properties against charged particles. A light-weight, inflatable habitat module called TransHab was built and shown to provide adequate protection against micrometeoroid impacts and good shielding properties against charged particle radiation in the International Space Station orbits. An experiment using a tissue equivalent proportional counter, to study the changes in dose and lineal energy spectra with graphite, aluminum, and a TransHab build-up as shielding, was carried out at the Los Alamos Nuclear Science Center neutron facility. It is a continuation of a previous study using regolith and doped polyethylene materials. This paper describes the results and their comparison with the previous study. Published by Elsevier Science Ltd.
Graphite nanofibers were synthesized and their hydrogen desorption and adsorption properties are reported for 77 and 300 K.
“Mid-passage corrosion” (MPC) was observed in NbC and ZrC-coated graphite (Gr)-based nuclear fuels during the NERVA/Rover programs. A new multilayered coating concept was proposed to solve this problem. The concept envisions designing a compliant multilayered coatings architecture to accommodate the thermal expansion mismatch strains between the ZrC outer coating and the Gr/(U,Zr)C fuel matrix. Additionally, the coating architecture uses diffusion barriers to minimize carbon diffusion from the substrate, and hydrogen diffusion from the flowing gas stream, into the multilayer coating. The present paper provides a brief overview of the development of multilayered coatings deposited on Gr disks, as well as within the inner channels of a19-hole hexagonal rod 152.4 mm long, by chemical vapor deposition (CVD) in proof-of concept studies. The cross-sectional microstructural observations are discussed. These trials have established that it is possible to deposit multilayered coatings by CVD in 19-hole hexagonal rods similar to the NERVA fuel rod design although the quality of the coatings and the uniformity of their thicknesses require further improvement.
Structure of the program Graphite material issues of interest How do things fit together Status of the program Baseline AGC Experiment Update AGC-4 and HDG-1 Irradiation Oxidation Modeling ASME Code development Discussion of how the data can be used Modeling behavior of core components Licensing/code development Interaction with vendors Collaborations (domestic and international)
This poster is to show the strength after oxidation of NBG-17 graphite at various mass loss percentages. This data is compared to previous data that had no standards of testing to establish an ASTM standard for future application.
Five Research Areas: Licensing and Code Graphite Research and Development Behavior Models Virgin Properties Mechanisms and Analysis Irradiation
Select necessary material properties Apply sampling plan Perform standardized testing Evaluate/compare properties Build NQA-1 qualified database Apply the “system” and database to the evaluation and qualification of future grades of graphite
Study results are presented for seven grades of graphite where 21 cylindrical samples were oxidized to a nominal level of mass loss. Low mass loss samples exhibited ~3% oxidative mass loss, intermediate ~8%, and high ~11%. Flat sample surfaces were covered during oxidation to minimize oxidation penetration at the top and bottom of each sample. Oxidized samples had their diameters reduced stepwise in 1 mm or 2 mm increments. Residual samples were weighed, geometric dimensions were recorded, and Archimedes measurements were taken at each step. Preliminary comparative graphical analysis is presented to illustrate the resultant density gradients observed. Raw tabular data are also provided.
Dry processing remains the primary solution for managing the down-blending of irradiated IGR HEU fuel. Several tasks have been initiated and completed to achieve this, including lab modernization, lab-scale and full-scale testing, designing and fabricating an in-paddle mixing drum, and commissioning both a down-blending system and a crushing and milling system. Additionally, a testing and training center was modernized, the equipment was successfully commissioned, and the IGR HEU fuel blocks were repackaged into daily containers. The training of operators and the construction of a new down-blending facility are tasks that will need to be completed in the near future. The progress in these areas continues to validate that the proposed method for down-blending irradiated HEU graphite fuel, followed by cementation of the down-blended material for permanent disposition, appears to be achievable.