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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Vibration behavior of fuel-element vibration suppressors for the advanced power reactor

Preliminary shock and vibration tests were performed on vibration suppressors for the advanced power reactor for space application. These suppressors position the fuel pellets in a pin type fuel element. The test determined the effect of varying axial clearance on the behavior of the suppressors when subjected to shock and vibratory loading. The full-size suppressor was tested in a mockup model of fuel and clad which required scaling of test conditions. The test data were correlated with theoretical predictions for suppressor failure. Good agreement was obtained. The maximum difference with damping neglected was about 30 percent. Neglecting damping would result in a conservative design.

Adams, D. W.↗
NASA NTRS1973

Thermally oscillating actuators

The actuator was redesigned to accommodate the new thermal motor for the Helios flipper. This design retained the basic configuration and dimensions of the original actuator. Changes were made primarily to the cradle and motor assembly. Because of the increased dimensions of the thermal motor, it was necessary to increase the diameter of the pellet case and associated parts including the back off spring and the piston return spring. The new springs were designed to yield the same spring rate differential as the originals. The design effort resulted in a new top assembly and approximately twenty sub-assembly and detail drawings. A list of drawings generated by EMR is attached.

Source record↗
NASA NTRS1974

Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

A search was made for new cationic conducting phases in alkali-tantalate and niobate systems. The phase equilibrium diagrams were constructed for the six binary systems Nb2O5-LiNbO3, Nb2O5-NaNbO3, Nb2O5-KNbO3, Ta2O5-NaTaO3, Ta2O5-LiTaO3, and Ta2O5-KTaO3. Various other binary and ternary systems were also examined. Pellets of nineteen phases were evaluated (by the sponsoring agency) by dielectric loss measurements. Attempts were made to grow large crystals of eight different phases. The system Ta2O5-KTaO3 contains at least three phases which showed peaks in dielectric loss vs. temperature. All three contain structures related to the tungsten bronzes with alkali ions in non-stoichiometric crystallographic positions.

Roth, R. S.↗
NASA NTRS1974

Quantitative multielement analysis using high energy particle bombardment

Charged particles ranging in energy from 0.8 to 4.0 MeV are used to induce resonant nuclear reactions, Coulomb excitation (gamma X-rays), and X-ray emission in both thick and thin targets. Quantitative analysis is possible for elements from Li to Pb in complex environmental samples, although the matrix can severely reduce the sensitivity. It is necessary to use a comparator technique for the gamma-rays, while for X-rays an internal standard can be used. A USGS standard rock is analyzed for a total of 28 elements. Water samples can be analyzed either by nebulizing the sample doped with Cs or Y onto a thin formvar film or by extracting the sample (with or without an internal standard) onto ion exchange resin which is pressed into a pellet.

Clark, P. J.↗
NASA NTRS1974

Beta-FeOOH, akaganeite, in lunar rocks

Experiments were conducted to determine the nature of the alteration process in lunar rocks. Mixtures of 10 wt.% Fe + 10 wt.% FeCl2 + 80 wt.% basalt (terrestrial) were pelletized and allowed to set for 48 hrs at 25 C, at 40% and at 100% relative humidity. The end products were examined by reflected-light microscopy and by X-ray diffraction. The degree of reaction appears to depend upon the amount of FeCl2, the availability of water and the Ni content of the metallic Fe. The experiments showed the extremely rapid rate at which the oxyhydration can occur in air and that the product is beta-FeOOH. The data from the FeOOH mineral in rock 66095 were compared with those obtained from synthetic beta-FeOOH and found to be identical. The 'rust' in the Apollo 16 rocks could result from oxyhydration of the samples, caused by water vapor contamination, all or part of which occurred in the Apollo spacecraft and/or upon return to earth. The akageneite (beta-FeOOH) in lunar rocks could be entirely of terrestrial origin as originally suggested by Taylor et al. (1973).

Taylor, L. A.↗
NASA NTRS1976

Space processing of chalcogenide glass

The manner in which the weightless, containerless nature of in-space processing can be successfully utilized to improve the quality of infrared transmitting chalcogenide glasses was investigated. The following conclusions were reached: (1) Laboratory experiments have established the techniques, processes and equipment necessary for the production of high purity chalcogenide glasses. (2) Processing techniques have been successfully adopted for Ge28Sb12Se60 glass in a 1-g environment. (3) The Ge28Sb12Se60 glasses that have been processed have optical transmission around 63% (5 mm thick). (4) Laboratory experiments have established that the use of precursor materials in powdered form increases the oxygen contamination of the processed glass. This indicates that high purity precursor materials in bar or pellet form should be used. (5) Modifications were made on the MSFC acoustic levitator in an attempt to improve levitation stability during long-time experiments. Room temperature experiments on As2S3 glasses and high temperature experiments on polystyrene were conducted.

Ali, M. A.↗
NASA NTRS1976

Preliminary results from screening tests of commercial catalysts with potential use in gas turbine combustors. Part 1: Furnace studies of catalyst activity

Thirty commercially produced monolith and pellet catalysts were tested as part of a screening process to select catalysts suitable for use in a gas turbine combustor. The catalysts were contained in a 1.8 centimeter diameter quartz tube and heated to temperatures varying between 300 and 1,200 K while a mixture of propane and air passed through the bed at space velocities of 44,000 to 70,000/hour. The amount of propane oxidized was measured as a function of catalyst temperature. Of the samples tested, the most effective catalysts proved to be noble metal catalysts on monolith substrates.

Anderson, D. N.↗
NASA NTRS1976

Extended analysis of Skylab experiment M558 data

A careful review of the data from Skylab M558 was made in an effort to explain the apparent anomaly of the existence of radial concentration gradients whereas none should bave been observed. The very close modelling of the experimental axial concentration profiles by the unsteady-state one-dimensional solution of Fick's Law of self-diffusion in liquid zinc, and the condition of initial uniform concentration in the radioactive pellet portion of the experimental specimens would have precluded the appearance of such radial concentration gradients. Statistical analyses were used to test the significance of the observed deviation from radial-concentration homogeneity. A student t-distribution test of significance showed that, at 90% or even at 80% level of significance, there were no significant deviations from uniformity in radial concentrations. It was also concluded that the two likely causes of any deviation that existed were the zinc to zinc-65 bonding procedure and surface phenomena such as surface tension and capillary action.

Ukanwa, A. O.↗
NASA NTRS1975

Effect of additions of coarse grains and fibers on the densification of a sinterable SiC

This note reports the effects on densification of independent additions of coarse equiaxed SiC grains and fibrous SiC that were mixed with fine beta-SiC to develop a duplex microstructure with improved toughness. The fine-matrix SiC did not contain excess boron and carbon. The equiaxed CVD beta-SiC was introduced in the fine beta-SiC matrix material in amounts of 5 and 10 wt%. Results indicate that the CVD beta-SiC, which is quite coarse, exhibits little indication of sinterability. The effect of these coarse-grained and fibrous additions on the sinterability of fine beta-SiC may result from a geometric type of interaction. This interpretation is reinforced by X-ray diffraction of the powders and sintered pellets via monochromatic CuK-alpha radiation; the diffraction patterns of the sintered composite structures are virtually a combination of those of the components. The addition of nonsinterable SiC to the sinterable material slightly reduces sinterability, the larger particles interacting geometrically with the fine matrix material to prevent complete densification.

Abe, H.↗
NASA NTRS1976

Preliminary results from screening tests of commercial catalysts with potential use in gas turbine combustors. I - Furnace studies of catalyst activity

Thirty commercially produced monolith and pellet catalysts were tested as part of a screening process to select catalysts suitable for use in a gas turbine combustor. The catalysts were contained in a 1.8 centimeter diameter quartz tube and heated to temperatures varying between 300 and 1200 K while a mixture of propane and air passed through the bed at space velocities of 44,000 to 70,000 per hour. The amount of propane oxidized was measured as a function of catalyst temperature. Of the samples tested, the most effective catalysts proved to be noble metal catalysts on monolith substrates.

Anderson, D. N.↗
NASA NTRS1977

Application of firefly luciferase assay for adenosine triphosphate (ATP) to antimicrobial drug sensitivity testing

The development of a rapid method for determining microbial susceptibilities to antibiotics using the firefly luciferase assay for adenosine triphosphate (ATP) is documented. The reduction of bacterial ATP by an antimicrobial agent was determined to be a valid measure of drug effect in most cases. The effect of 12 antibiotics on 8 different bacterial species gave a 94 percent correlation with the standard Kirby-Buer-Agar disc diffusion method. A 93 percent correlation was obtained when the ATP assay method was applied directly to 50 urine specimens from patients with urinary tract infections. Urine samples were centrifuged first to that bacterial pellets could be suspended in broth. No primary isolation or subculturing was required. Mixed cultures in which one species was predominant gave accurate results for the most abundant organism. Since the method is based on an increase in bacterial ATP with time, the presence of leukocytes did not interfere with the interpretation of results. Both the incubation procedure and the ATP assays are compatible with automation.

Picciolo, G. L.↗
NASA NTRS1977

A stone's throw into the universe: A memoir

Early goals in experimental astronomy are recalled. Physio-chemical properties of the atmosphere were studied by observing the tracks and point-to-point spectra of fast particles from artificial meteors. Some of these self-luminous pellets were fired from an Aerobee rocket in 1958.

Zwicky, F.↗
NASA NTRS1976

Heat pipe nuclear reactor for space power

A heat-pipe-cooled nuclear reactor has been designed to provide 3.2 MWth to an out-of-core thermionic conversion system. The reactor is a fast reactor designed to operate at a nominal heat-pipe temperature of 1675 K. Each reactor fuel element consists of a hexagonal molybdenum block which is bonded along its axis to one end of a molybdenum/lithium-vapor heat pipe. The block is perforated with an array of longitudinal holes which are loaded with UO2 pellets. The heat pipe transfers heat directly to a string of six thermionic converters which are bonded along the other end of the heat pipe. An assembly of 90 such fuel elements forms a hexagonal core. The core is surrounded by a thermal radiation shield, a thin thermal neutron absorber, and a BeO reflector containing boron-loaded control drums.

Koening, D. R.↗
NASA NTRS1975

Quantitative multielement analysis using high energy particle bombardment

Charged particles ranging in energy from 0.8 to 4.0 MeV are used to induce resonant nuclear reactions, Coulomb excitation (gamma-rays), and X-ray emission in both thick and thin targets. Quantitative analysis is possible for elements from Li to Pb in complex environmental samples, although the matrix can severely reduce the sensitivity. It is necessary to use a comparator technique for the gamma-rays while for X-rays an internal standard can be used. A USGS standard rock is analyzed for a total of 28 elements. Water samples can be analyzed either by nebulizing the sample doped with Cs or Y a thin Formvar film or by extracting the sample onto ion exchange resin which is pressed into a pellet.

Clark, P. J.↗
NASA NTRS1978

Automatic primate feeder

Zippered tubing and rotating wheel dispense food pellets reliably without contamination.

Gandy, A. R.↗
NASA NTRS1977

The MJS-77 magnetometer actuator

A two-position (0 deg and 180 deg) actuating mechanism (flipper) driven by alternately-heated wax motors (pellets) used to rotate the low field triaxial fluxgate magnetometer experiment on the 1977 Mariner Jupiter-Saturn spacecraft to its 0 deg and 180 deg positions is described. The magnetic field, power requirements, weight and volume of this device are discussed. The problems encountered in design and development of this mechanism are presented.

Stange, W. C.↗
NASA NTRS1978

Molded composite pyrogen igniter for rocket motors

A lightweight pyrogen igniter assembly including an elongated molded plastic tube adapted to contain a pyrogen charge was designed for insertion into a rocket motor casing for ignition of the rocket motor charge. A molded plastic closure cap provided for the elongated tube includes an ignition charge for igniting the pyrogen charge and an electrically actuated ignition squib for igniting the ignition charge. The ignition charge is contained within a portion of the closure cap, and it is retained therein by a noncorrosive ignition pellet retainer or screen which is adapted to rest on a shoulder of the elongated tube when the closure cap and tube are assembled together. A circumferentially disposed metal ring is provided along the external circumference of the closure cap and is molded or captured within the plastic cap in the molding process to provide, along with O-ring seals, a leakproof rotary joint.

Heier, W. C.↗
NASA NTRS1977

Low cost silicon solar array project silicon materials task: Establishment of the feasibility of a process capable of low-cost, high volume production of silane (step 1) and the pyrolysis of silane to semiconductor-grade silicon (step 2)

Extended operation of a small process-development unit routinely produced high quality silane in 97+% yield from dichlorosilane. The production rate was consistent with design loadings for the fractionating column and for the redistribution reactor. A glass fluid-bed reactor was constructed for room temperature operation. The behavior of a bed of silcon particles was observed as a function of various feedstocks, component configurations, and operating conditions. For operating modes other than spouting, the bed behaved in an erratic and unstable manner. A method was developed for casting molten silicon powder into crack-free solid pellets for process evaluation. The silicon powder was melted and cast into thin walled quartz tubes that sacrificially broke on cooling.

Breneman, W. C.↗