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At least 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Concepts for Actinide Recovery from TRISO Used Nuclear Fuel

The work described in this report has developed a preliminary conceptual flowsheet based on limited published literature for the head-end of a TRISO oxycarbide UNF reprocessing plant. The essential function of the head-end is to prepare the UNF for subsequent separation of actinides. The main steps of the conceptual TRISO UNF head-end reprocessing flowsheet are: 1. Fragmentation of the graphite moderator to expose the fuel particles. 2. Separation of fuel particles from fragmented graphite moderator by sieving and fluidization. 3. Fragmentation of the fuel particles to expose the fuel kernel. 4. Dissolution of the fuel kernel in nitric acid. Noteworthy at this step is the formation of organic acids (mainly oxalic and mellitic acids) from the carbon associated with the fuel and TRISO coatings. These acids can interfere with actinide separations and solvent extraction hydraulic performance and carbon dioxide gas generation. 5. Clarification of the dissolved fuel solution to separate the coating fragments. 6. Dissolver off-gas treatment with specific emphasis on managing generation of carbon dioxide gas containing carbon-14. The quantity of carbon dioxide is projected to be 100 to 1000 times greater than that arising from dissolving LWR UNF. Pre or post treatment of the exposed fuel kernels could be undertaken to mitigate the formation of organic acids but there still exists a significant off-gas treatment challenge. The literature on reprocessing uranium nitride UNF was reviewed but a flowsheet was not specifically developed since its scope and uncertainties are expected to be encompassed by the oxycarbide flowsheet. Overall, the predominant feature of processing TRISO UNF is carbon management to reduce waste volume and mitigate the formation of carbon dioxide and organic acids. This report recommends broad areas of research that will help to further define the head-end flowsheet.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2026

Digital Twin User Guide for Chelan County Public Utility District

This user manual offers a comprehensive guide for developing a Digital twin (DT) of a Kaplan turbine at Chelan County Public Utility District (Chelan PUD) using neural networks. As variable renewable generation expands, hydropower units must operate with optimal efficiency and stability. For Kaplan machines, this flexibility is achieved through coordinated control of guide vane (wicket gates) opening and runner blade pitch, which amplifies the plant’s inherent nonlinear behavior and challenges traditional physics-only modeling. The efficiency of the Kaplan turbine varies with different combinations of the guide vans (wicket gate) opening and the blade angle. Each guide van opening and blade angle has a corresponding highest efficiency point, forming a cam relationship that represents the optimal combination.The discharge of a hydraulic turbine is controlled by the opening angle of the guide vans. Therefore, for each value of head, there is a certain guide van opening and blade angle that corresponds to the highest efficiency. For a given head, different combinations of the guide van opening and blade angle have different efficiencies. Therefore, coordinate cam curves are used to describe the relationship between the wicket gate opening and blade angle with different water head. To address these challenges, the manual details a data-driven modeling and learning workflow centered on structured neural networks. The approach is designed to forecast critical operational variables—discharge flow, net head, penstock (or scroll-case) pressure, and generator electrical outputs—by leveraging real-time inputs such as the generator power control setpoint, exciter field current and field voltage, together with hydromechanical commands (e.g., gate position and, when available, runner blade-pitch angle). The neural models are trained and validated on operational data from a Kaplan unit operated by Chelan PUD, demonstrating that the structured NN architecture can learn the coupled gate–blade–electrical dynamics. The result is a robust DT that improves situational awareness and supports data-informed decision-making for Chelan PUD’s Kaplan turbine operations.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2020

NGC 4869 in the Coma Cluster: Twist, Wrap, Overlap, and Bend

The upgraded Giant Metrewave Radio Telescope (GMRT) has been used to image the head–tail radio galaxy NGC 4869 in the Coma cluster with an angular resolution of 6.″26 at 250–500 MHz and 2.″18 at the 1050–1450 MHz bands. The archival legacy GMRT data have also been used to image the source with angular resolutions from 4.″9 to 21.″8 at 610 MHz, 325 MHz, 240 MHz, and 150 MHz. We find that the ∼200 kpc scale radio morphology consists of five distinct regions with the clear presence of a pinch at ≈1.′4 (=38.8 kpc) and a ridge at ≈3.′4 (=94.2 kpc) from the head. The sharp bend by ∼70° at ∼3.′5 (=97 kpc) from the head is possibly due to projection effects. The radio spectra show progressive spectral steepening as a function of distance from the head and there is possibly re-acceleration of the synchrotron electrons and perhaps also magnetic field regeneration in the 6″–208″ (=2.8–96.1 kpc) region of the jet. We report a steep spectrum sheath layer enveloping a flat spectrum spine, hinting at a transverse velocity structure with a fast-moving spine surrounded by a slow-moving sheath layer. We also derive the lifetimes of the radiating electrons and equipartition parameters. A plausible explanation for the characteristic feature, a ridge of emission perpendicular to the direction of tail is the flaring of a straight, collimated radio jet as it crosses a surface brightness edge due to Kelvin–Helmholtz instabilities.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Comet Tails of Type 2

A summary is presented of a theory for the head and tail regions of Type 2 (dust) comets, wherein dust particles having a wide distribution of sizes are assumed to be released from the comet nucleus in an essentially continuous manner in time during the period of distinctive cometary phenomena. The dust particles are assumed to be accelerated radially outward from the nucleus as a result of a drag interaction with the expanding gas in the comet head. In the tail region the only significant forces assumed to act on the dust particles are solar gravity and the force of solar radiation pressure. It is shown how results describing the surface density in the tail are obtained and how by matching calculated distributions with measured ones it is possible to determine the dust and head-gas emission rates as a function of time, the distribution of dust particle sizes, and the emission velocity from the inner head region as a function of particle size and time. The results of matching calculated density distributions with light intensity measurements from Comet Arend-Roland 1956h are summarized.

Probstein, R. F.↗
NASA NTRS1973

Terminal guidance system

A terminal guidance system is described including a heading command subsystem and a glide-slope command subsystem which develop command signals for use in guiding an aircraft or other vehicle into a preselected heading and/or altitude at a terminal point. The heading command subsystem is responsive to certain input data and continuously develops command signals for use in directing the aircraft from a remote location to a terminal point so that upon arrival it has a preselected terminal heading. The glide-slope command subsystem is responsive to certain other input data and continuously develops command signals for use in controlling the rate of descent of the aircraft so that it will have a preselected altitude and glide-slope upon arrival at the terminal.

Gee, S. W.↗
NASA NTRS1973

Simulator evaluation of display concepts for pilot monitoring and control of space shuttle approach and landing. Phase 2: Manual flight control

A study of the display requirements for final approach management of the space shuttle orbiter vehicle is presented. An experimental display concept, providing a more direct, pictorial representation of the vehicle's movement relative to the selected approach path and aiming points, was developed and assessed as an aid to manual flight path control. Both head-up, windshield projections and head-down, panel mounted presentations of the experimental display were evaluated in a series of simulated orbiter approach sequence. Data obtained indicate that the experimental display would enable orbiter pilots to exercise greater flexibility in implementing alternative final approach control strategies. Touchdown position and airspeed dispersion criteria were satisfied on 91 percent of the approach sequences, representing various profile and wind effect conditions. Flight path control and airspeed management satisfied operationally-relevant criteria for the two-segment, power-off orbiter approach and were consistently more accurate and less variable when the full set of experimental display elements was available to the pilot. Approach control tended to be more precise when the head-up display was used; however, the data also indicate that the head-down display would provide adequate support for the manual control task.

Gartner, W. B.↗
NASA NTRS1978

Remote sensing of crop type and maturity

A red-shift in the chlorophyll absorption edge of heading wheat and grain sorghum is clearly visible in high-spectral-resolution measurements made from a low-flying aircraft over Imperial Valley, California. The position of the absorption edge shifts progressively toward the longer wavelengths during the crop growth cycle. The red-shift of 7 to 10 nm can be measured by using 10 nm-wide spectral bands, centered at 745 nm and 785 nm. These two bands, plus a band in the pigment absorption region at 670 nm, contain enough information to identify wheat and grain sorghum in the heading stage, to indicate the degree of heading, and to indicate canopy density during the heading stage

Collins, W.↗
NASA NTRS1980

Fire extinguishing apparatus having a slidable mass for a penetrator nozzle

A fire extinguishing apparatus for delivering an extinguishing agent through a tarrier surrounding a structure into its interior includes an elongated tubular nozzle body which has a pointed penetrating head carried on one end of the tubular body. A source of extinguishing agent coupled to the opposite end of the tubular body is fed through and passes through passages adjacent the head for delivering the extinguishing agent to the interior of the structure. A slidable mass is carried on the tubular body on a remote end of the tubular body from the penetrating head. By manipulating the slidable mass and bringing such in contact with an abutment the force imparted to the tubular body causes the head to penetrate the structure.

Gray, N. C.↗
NASA NTRS1980

Method and tool for machining a transverse slot about a bore

A method and apparatus for cutting a transverse slot about a bore of smaller diameter than that of the slot are disclosed. The invention consists of introducing a cutting head facing transversely to the bore, through the bore opening its distance from the mill shaft being progressively extended by the addition of spacers between the head and the shaft until the desired slot depth is obtained. The spacers are held in position by a cable passing from the cutting head through the series of spacers and out along the mill shaft. The mill shaft carrying the cutting head is moved transversely into the object wherein the slot is being cut as the object is being rotated thereabout by the mill table to which it is affixed.

David-Malig, M. A.↗
NASA NTRS1980

Experiments on multiple vortices in a side dump gas generator ramjet

The role of multiple vortices in the flame stabilization process of a 4 inlet side dump ramjet was determined. Very rich propane air mixtures were injected at the head to simulate a gas generator ramjet. Swirl was introduced by canting the inlets at the dump station. The inlet angle, swirl angle, and the distance of the head from the dump station were varied over a wide range to determine the importance of the vortices located at the dump stations and at the head. It is shown that with proper design, the vortex at the head can be made to perform as a pilot burner allowing a great deal of versatility of operation and it appears to provide all the criteria of pollution free operation.

Choudhury, P. R.↗
NASA NTRS1982

MC carbide structures in M(lc2)ar-M247

The morphologies and distribution of the MC carbides in Mar-M247 ingot stock and castings were investigated using metallographic, X-ray diffraction and energy-dispersive X-ray analysis techniques. The MC carbides were found to form script structures during solidification. The script structures were composed of three distinct parts. The central cores and elongated arms of the MC carbide script structures had compositions (Ti, Cr, Hf, Ta, W)C and lattice parameters of 4.39 A. The elongated script arms terminated in enlarged, angular "heads". The heads had compositions (Ti, Hf, Ta, W)C and lattice parameters of approximately 4.50 A. The heads had a higher Hf content than the cores and arms. The size of the script structures, as well as the relative amount of head-type to core and arm-type MC carbide, was found to be determined by solidification conditions. No carryover of the MC carbides from the ingot stock to the remelted and cast material was observed.

Wawro, S. W.↗
NASA NTRS1982

Short term /1 and 3 day/ cardiovascular adjustments to suspension antiorthostasis in rats

Antiorthostasis (AO) results in responses reflective of thoracic vessel loading. Initial findings included fluid and electrolyte shifts (diuresis and natriuresis) in AO but not in orthostatic (O) rats. This study aims at obtaining supportive evidence for cardiovascular responses, E.g., blood pressure and related parameters, in light of the original hypothesis. Tilting rats rapidly head-up from either horizontal (O) or head-down (AO) positions was used to assess cardiovascular sensitivities. O and AO rats were used after 1 or 3 days of suspension. Rats were controls (C), pre-tilted O and AO, tilted O and AO (rapid head-up 70-80 deg); post-tilted (to original postures). MAP in C rats was 108 +2 mmHg, in O, (117 + or - 1.02) and AO, (120 + or - 0.58). MAP, diastolic pressure (DP) and pulse pressure were consistently elevated in AO rats on day 3. With rapid head-up tilt, only MAP and DP showed significant increases. These changes were seen as cardiovascular responses to AO and support further use of this rat model for AO studies.

Musacchia, X. J.↗
NASA NTRS1983

Fluid shifts and muscle function in humans during acute simulated weightlessness

The acute effects of simulated weightlessness on transcapillary fluid balance, tissue fluid shifts, muscle function, and triceps surface reflex time were studied in eight supine human subjects who were placed in a 5 degrees head-down tilt position for 8 hr. Results show a cephalic fluid shift from the legs as indicated by facial edema, nasal congestion, increased urine flow, decreased creatinine excretion, reduced calf girth, and decreased lower leg volume. The interstitial fluid pressure in the tibialis anterior muscle and subcutaneous tissue of the lower leg was found to fall significantly, while other transcapillary pressures (capillary and interstitial fluid colloid osmotic pressures) were relatively unchanged. The total water content of the soleus muscle was unchanged during the head-down tilt. After head-down tilt, isometric strength and isokinetic strength of the plantar flexors were unchanged, while the triceps surae reflex time associated with plantar flexion movement slowed slightly. These results demonstrate a dehydration effect of head-down tilt on muscle and subcutaneous tissue of the lower leg that may affect muscle function.

Hargens, A. R.↗
NASA NTRS1983

Spatial orientation - Visual-vestibular-somatic interaction

The compensation signals from somatosensory and vestibular receptors, which act to compensate for disturbances produced by the displacement of our eyes relative to other parts of our bodies and for visual disturbances such as tilted frames or moving visual fields, are investigated. Disturbances were evoked by tilting the head and by rotating a large visual display, while compensation signals related to gravity were altered by placing the subjects horizontally on a board or seating them vertically. The first experiment studied the effects of visual disturbance on the ability of supine observers to set a line to the longitudinal body axis while the head was tilted toward one shoulder or while the head was straight. Results showed that the effects of the visual disturbance were greater when the head was tilted than when it was straight, which indicates that the effects of visual disturbance were greater for a task that required compensation. The second experiment compared the performance of supine and erect observers. No differences were found between the performance of observers on a task requiring the use of compensation signals under these two conditions, which suggests that the enrichment of compensatory signals did not reduce the effects of visual disturbancs.

Parker, D. E.↗
NASA NTRS1985

Apparatus and method to keep the walls of a free-space reactor free from deposits of solid materials

An apparatus and method is disclosed for keeping interior walls of a reaction vessel free of undesirable deposits of solid materials in gas-to-solid reactions. The apparatus includes a movable cleaning head which is configured to be substantially complementary to the interior contour of the walls of the reaction vessel. The head ejects a stream of gas with a relatively high velocity into a narrow space between the head and the walls. The head is moved substantially continuously to at least intermittently blow the stream of gas to substantially the entire surface of the walls wherein undesirable solid deposition is likely to occur. The disclosed apparatus and process is particularly useful for keeping the walls of a free-space silane-gas-to-solid-silicon reactor free of undesirable silicon deposits.

Yamakawa, K. A.↗
NASA NTRS1985

Sensory and motor properties of the cerebellar uvula and modulus

The uvula and nodulus (vermal lobules 9 and 10) of the vestibulocerebellum are implicated by behavioral evidence in the control of eye and head movements and in the production of motion sickness. The uvula and nodulus could play a role in these functions through known output pathways. Purkinje cells in both structures project via the fastigial and vestibular nuceli to the ventral horn of the cervical spin cord, to oculomotor neurons, and to the emetic region of the reticular formation (ablation of which abolishes susceptability to motion sickness). Uvula and nodulus Purkinje cells will be analyzed in cats trained to make controlled head movements. The activity of these neurons is expected to modulate well during head and/or eye movements because the uvula and nodulus receive heavy projections from sources of visual, vestibular and neck proprioceptive information. How neuron activity contributes to movement and how different sensory inputs converge to influence this contribution may be determined by characterizing movement related properties of these neurons. A population of neurons that modulates powerfully to the conflict between different head movement signals that can cause motion sickness may be identified.

Robinson, F. R.↗
NASA NTRS1985

DE 1 RIMS operational characteristics

The Retarding Ion Mass Spectrometer (RIMS) on the Dynamics Explorer 1 spacecraft observes both the thermal and superthermal (50 eV) ions of the ionosphere and inner magnetosphere. It is capable of measuring the detailed species distribution function of these ions in many cases. It was equipped with an integral electrometer to permit in-flight calibration of the detector sensitivities and variations thereof. A guide to understanding the RIMS data set is given. The reduction process from count rates to physical quantities is discussed in some detail. The procedure used to establish in-flight calibration is described, and results of a comparison with densities from plasma wave measurements are provided. Finally, a discussion is provided of various anomalies in the data set, including changes of channeltron efficiency with time, spin modulation of the axial sensor heads, apparent potential differences between the sensor heads, and failures of the radial head retarding potential sweep and of the -Z axial head aperture plane bias. Studies of the RIMS data set should be conducted only with a thorough awareness of the material presented here, or in collaboration with one of the scientists actively involved with RIMS data analysis.

Olsen, R. C.↗
NASA NTRS1987

Improved Flux-Gate Magnetometer

Simplified circuit drives heading indicator and senses magnetic field of Earth. Simple flux-gate magnetometer supplies digital readout of magnetic heading of vehicle, developed to drive heading indicator, or supply heading information to autopilot or to other navigational instruments. Important feature is core driven into saturation in one direction only by alternating drive voltage, which swings from zero to one polarity and back. Made in part of commercially available integrated circuits.

Garner, H. Douglas↗