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  Partner: UNT Libraries Government Documents Department
 Decade: 1990-1999
Design, Analysis, and Optimization of a Radioisotope Thermophotovoltaic (RTPV) Generator, and its Applicability to an Illustrative Space Mission

Design, Analysis, and Optimization of a Radioisotope Thermophotovoltaic (RTPV) Generator, and its Applicability to an Illustrative Space Mission

Date: October 1, 1994
Creator: Schock, Alfred; Mukunda, Meera; Or, Chuen T; Kumar, Vasanth & Summers, G.
Description: Paper presented at the 45th Congress of the IAF in Jerusalem, Israel, October 1994. The paper describes the results of a DOE-sponsored design study of a radioisotope thermophotovoltaic generator (RTPV), to complement similar studies of Radioisotope Thermoelectric Generators (RTGs) and Stirling Generators (RSGs) previously published by the authors. To focus the design effort, it was decided to direct it at a specific illustrative space mission, Pluto Fast Flyby (PFF). That mission, under study by the JPL, envisages a direct eight to nine-year flight to Pluto (the only unexplored planet in the solar system), followed by comprehensive mapping, surface composition, and atmospheric structure measurements during a brief flyby of the planet and its moon Charon, and transmission of the recorded science data to Earth during a six-week post-encounter cruise.
Contributing Partner: UNT Libraries Government Documents Department
Basin Analysis of the Mississippi Interior Salt Basin and Petroleum System Modeling of the Jurassic Smackover Formation, Eastern Gulf Coastal Plain

Basin Analysis of the Mississippi Interior Salt Basin and Petroleum System Modeling of the Jurassic Smackover Formation, Eastern Gulf Coastal Plain

Date: December 22, 1997
Creator: Mancini, Ernest A.
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Design and Analysis of RTGs for Solar and Martian Exploration Missions

Design and Analysis of RTGs for Solar and Martian Exploration Missions

Date: May 1, 1990
Creator: Schock, Alfred
Description: The paper described the results of design, analysis and spacecraft integration studies of Radioisotope Thermoelectric Generators (RTGs) for three unmanned space exploration missions. The three missions, consisting of the Mars Rover and Sample Return (MRSR) mission, the Solar Probe mission, and the Mars Global Net work (MGN) mission, are under study by the Jet Propulsion Laboratory (JPL) for the U.S. National Aeronautics and Space Administration (NASA). The NASA/JPL mission studies are supported by the U.S. Department of Energy's Office of Special Applications (DOE/OSA), which has commissioned Fairchild Space Company to carry out the required RTG design studies.
Contributing Partner: UNT Libraries Government Documents Department
Thermal Analysis on the Shipment of Russian Plutonium Fuel

Thermal Analysis on the Shipment of Russian Plutonium Fuel

Date: January 1, 1995
Creator: Or, Chuen T; Skrabek, Emanuel A & Carpenter, Robert T
Description: Paper presented at the 12th Symposium on Space Nuclear Power and Propulsion in Albuquerque, NM in January 1995. The Mound 9516 shipping package was designed for the shipment of Plutonium-238 fuel. One of the shipping configurations is the Russian Pu-238 powder can. Computer models using SINDA were created to predict the temperatures of the package under normal conditions of transport (NCT: 38oC ambient temperature), under hypothetical accident conditions (HAC: engulfed in fire for 30 minutes), and inside a standard cargo container. Pressure increases inside the package due to the expansion of the trapped gases and helium gas generation from isotope decay were also analyzed. There is a duplicate copy and also a copy in the ESD Files.
Contributing Partner: UNT Libraries Government Documents Department
Fabrication and Testing of Full-Length Single-Cell Externally Fueled Converters for Thermionic Reactors

Fabrication and Testing of Full-Length Single-Cell Externally Fueled Converters for Thermionic Reactors

Date: June 1, 1994
Creator: Schock, Alfred
Description: The preceding paper described designs and analyses of thermionic reactors employing full-core-length single-cell converters with their heated emitters located on the outside of their internally cooled collectors, and it presented results of detailed parametric analyses which illustrate the benefits of this unconventional design. The present paper describes the fabrication and testing of full-length prototypical converters, both unfueled and fueled, and presents parametric results of electrically heated tests. The unfueled converter tests demonstrated the practicality of operating such long converters without shorting across a 0.3-mm interelectrode gap. They produced a measured peak output of 751 watts(e) from a single diode and a peak efficiency of 15.4%. The fueled converter tests measured the parametric performance of prototypic UO(subscript 2)-fueled converters designed for subsequent in-pile testing. They employed revolver-shaped tungsten elements with a central emitter hole surrounded by six fuel chambers. The full-length converters were heated by a water-cooled RF-induction coil inside an ion-pumped vacuum chamber. This required development of high-vacuum coaxial RF feedthroughs. In-pile test rules required multiple containment of the UO (subscript 2)-fuel, which complicated the fabrication of the test article and required successful development of techniques for welding tungsten and other refractory components. The test measured a peak power output ...
Contributing Partner: UNT Libraries Government Documents Department
Thermionic Reactor Design Studies

Thermionic Reactor Design Studies

Date: August 1, 1994
Creator: Schock, Alfred
Description: Paper presented at the 29th IECEC in Monterey, CA in August 1994. The present paper describes some of the author's conceptual designs and their rationale, and the special analytical techniques developed to analyze their (thermionic reactor) performance. The basic designs, first published in 1963, are based on single-cell converters, either double-ended diodes extending over the full height of the reactor core or single-ended diodes extending over half the core height. In that respect they are similar to the thermionic fuel elements employed in the Topaz-2 reactor subsequently developed in the Soviet Union, copies of which were recently imported by the U.S. As in the Topaz-2 case, electrically heated steady-state performance tests of the converters are possible before fueling.
Contributing Partner: UNT Libraries Government Documents Department
Closed-Form Solution for the Effect of Fuel Decay and Thermoelectric Degradation on Output of SiGe RTGs

Closed-Form Solution for the Effect of Fuel Decay and Thermoelectric Degradation on Output of SiGe RTGs

Date: August 1, 1991
Creator: Schock, Alfred
Description: Presented at the 26th IECEC in Boston, MA August 4-9, 1991. The paper derives a closed-form solution for the long-term effect of fuel decay and thermoelectric degradation on the performance of Radioisotope Thermoelectric Generators employing silicon-germanium converter elements. RTGs of this type were used to power the recent Galileo and Ulysses space exploration missions, and are slated for use on the upcoming CRAF and Cassini missions. The method described applies not only to uniform-temperature RTGs, but also to RTGs with significant axial and circumferential variations in the couples' cold-junction temperatures and voltages (due to unsymmetrically obstructed heat rejection paths). This is important for the mutually blocking RTGs on the CRAF and Cassini spacecraft, and even more so for the reflector-blocked Solar Probe RTGs. The method for predicting RTG degradation that is dervied in this paper is based on both analytical and experimental data. It accounts for the effect of diminishing hot-junction temperatures on thermoelectric degradation rates. The method leads to an integral equation, for which the author was able to derive a closed-form solution. The solution was successfully validated by comparison with long-term test data. It enables the RTG designer to predict the power output profile throughout the mission, to ...
Contributing Partner: UNT Libraries Government Documents Department
Space nuclear power, propulsion, and related technologies.

Space nuclear power, propulsion, and related technologies.

Date: January 1, 1992
Creator: Berman, Marshall
Description: Sandia National Laboratories (Sandia) is one of the nation's largest research and development (R&D) facilities, with headquarters at Albuquerque, New Mexico; a laboratory at Livermore, California; and a test range near Tonopah, Nevada. Smaller testing facilities are also operated at other locations. Established in 1945, Sandia was operated by the University of California until 1949, when, at the request of President Truman, Sandia Corporation was formed as a subsidiary of Bell Lab's Western Electric Company to operate Sandia as a service to the U.S. Government without profit or fee. Sandia is currently operated for the U.S. Department of Energy (DOE) by AT&T Technologies, Inc., a wholly-owned subsidiary of AT&T. Sandia's responsibility is national security programs in defense and energy with primary emphasis on nuclear weapon research and development (R&D). However, Sandia also supports a wide variety of projects ranging from basic materials research to the design of specialized parachutes. Assets, owned by DOE and valued at more than $1.2 billion, include about 600 major buildings containing about 372,000 square meters (m2) (4 million square feet [ft2]) of floor space, located on land totalling approximately 1460 square kilometers (km2) (562 square miles [mi]). Sandia employs about 8500 people, the majority in ...
Contributing Partner: UNT Libraries Government Documents Department
Uniform Fin Sizes versus Uniform Fin Root Temperatures for Unsymmetrically Obstructed Solar Probe RTGs

Uniform Fin Sizes versus Uniform Fin Root Temperatures for Unsymmetrically Obstructed Solar Probe RTGs

Date: August 1, 1991
Creator: Schock, Alfred; Or, Chuen T & Noravian, Heros
Description: Paper presented at the 26th IECEC, August 4-9, 1991 in Boston, MA. The Solar Probe will approach the sun within four solar radii or 0.02 AU. Because of that proximity, the spacecraft must be protected by a thermal shield. The protected umbra is a cone of 4 m diameter and 7.5 m height, and all temperature-sensitive flight components must fit within that cone. Therefore, the RTGs which power the Solar probe cannot be separated from each other and from other payload components by deploying them on long booms. They must be located near and thermally isolated from the spacecraft's paylod. This paper compares the performance of such variable-fin RTGs with that of uniform-fin RTGs. It derives the fin dimensions required for circumferential isothermicity, identifies a design that maximizes the RTGs specific power, and proves the practicality of that design option. However, detailed thermal and electrical analyses led to the somewhat surprising conclusion that (for a given thermal power) the non-uniform-fin design results in the same power output, at a higher maximum hot-junction temperature, as the standard uniform-fin design, despite the latter's nonuniform cold-junction temperatures. There are three copies in the file.
Contributing Partner: UNT Libraries Government Documents Department
Development of Nanoscale Ceramics for Advanced Power Applications

Development of Nanoscale Ceramics for Advanced Power Applications

Date: September 30, 1999
Creator: Leffler, Miriam & Helble, Joseph
Description: Bulk structures of unstabilized ZrO{sub 2-x}, with x in the range of 0 {<=} x {<=} 0.44, at ambient pressure have been found to exist in three different structures. (monoclinic, tetragonal and cubic.). At ambient temperature and elevated pressures above 3.5 GPa, unstabilized zirconia at these same compositions is found as a fourth phase, the orthorhombic phase. Work done in this project has demonstrated that nanoscale zirconia particles containing the orthorhombic phase in addition to amorphous material can be produced through solgel methods. Extensive characterization of this material including recent high temperature x-ray diffraction work has indicated that the structure of the synthesized zirconia appears to be linked to the oxygen vacancy population in the material, and that water appears to be a critical factor in determining the type of material formed during synthesis. These results suggest that surface energy alone is not the controlling factor in determining crystal phase.
Contributing Partner: UNT Libraries Government Documents Department
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