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INVESTIGATION OF GAS PRESSURE BUILDUP IN THERMOELECTRIC SNAP GENERATORS

Description: The program for investigating gas pressure buildup in thermoelectric generators was initiated in February 1963 and continued through December 1963. The program objectives were to determine the source(s) of internal gas pressure increase in SNAP thermoelectric generators, establish methods of alleviating or eliminating the condition, and conduct a proof-of-principle test on an electrically heated 60-watt thermoelectric SNAP generator to determine the effectiveness of the procedures developed to control or eliminate the condition. The gas pressure increase in the generators that were initially filled with dry inert gas results from decomposition of the phenol-formaldehyde resin that is used as a binder in the Min-K 1301 thermal insulation and desorption of atmospheric gases and water vapor that adsorb on the surface of the insulation. The degree of gas release in both cases was determined to be temperature and pressure dependent. The recommended procedure to control gas pressure buildup for all future generators is: (1) precondition the Min-K by burning off the phenolic resin binder; (2) vacuum outgas the insulation at a temperature above its maximum operating temperature; and (3) install a gas getter (zirconium) to absorb any gases that may be released during subsequent generator operation. The complete recommended procedure to control this pressure buildup could not be employed in the 60-watt thermoelectric SNAP generator test since the generator had been previously constructed and assembled using Min-K that had not been preconditioned by outgassing. Therefore, a modified outgassing procedure was established for the generator when the test was initiated. The procedure, in essence, specified that the generator be maintained on continuous evacuation while the thermoelement hot junction temperature was slowly increased to approximates 525 deg F, and that the generator be subjected to frequent rapid evacuations and gas changes as the temperature was increased to 960 deg F. (Lead telluride thermoelements begin ...
Date: January 1, 1964
Creator: McDonald, W.A. & McGrew, J.
Partner: UNT Libraries Government Documents Department

PRODUCTION OF STRONTIUM-TITANATE RADIOISOTOPE FUEL FOR SNAP 7B THERMOELECTRIC GENERATOR

Description: The conversion of strontium-90 to strontium titanate heat source pellets is described. Encapsulation of the fuel in Hastelloy C containers and necessary leak testing, decontamination and calorimetry procedures are covered. Loading of the SNAP 7B thermoelectric generator was accomplished. (auth)
Date: April 15, 1963
Creator: Bloom, J.L.
Partner: UNT Libraries Government Documents Department

SNAP 7D--STRONTIUM-90 FUELED THERMOELECTRIC GENERATOR POWER SOURCE. THIRTY- WATT U.S. NAVY FLOATING WEATHER STATION. Final Report

Description: The objectives of the SNAP-7D program were to design, manufacture, test and deliver a thirty-watt electric generating system for a modified U. S. Navy NOMAD-class weather buoy to be stationed in the Gulf of Mexico. The sixty-watt Sr/sup 90/ thermoelectric generator, the relay panel, the batteries, and the installation of the system in a boattype buoy are described. In addition to delivering the power supply, many tests were required for the SNAP-7D system to demonstrate its conformance to the contract statement of work. The electrical tests of the generator and of the system, the shock and vibration tests, and the tests at the environmental temperature extremes are discussed. (auth) Quantitative studies were made of the angular distribution of elastic and inelastic scattering of 25-kev electrons on noble gases, and the results were compared with scattering theory in the Born approximation. Results are presented in tables and graphs. (M.C.G.)
Date: March 15, 1963
Creator: Young, C.N.
Partner: UNT Libraries Government Documents Department

Characteristics of Fuel Compounds and Encapsulation Materials in Radioisotope Heat Sources

Description: The properties of radioisotope fuel compounds and fuel capsule materials which are pertinent to the design and operation of radioisotope heat sources are outlined. These properties are grouped into the following categories: intrinsic, extrinsic, and compatibility. The properties of strontium titanate as the fuel and Hastelloy C as the capsule material are evaluated. (D.L.C.)
Date: April 17, 1963
Partner: UNT Libraries Government Documents Department

SNAP PROGRAMS-UPPER ATMOSPHERE EXPERIMENTAL RE-ENTRY STUDY. Final Summary Report

Description: An experimental flight test was made to verify and improve the methods and techniques used to predict the aerothermodynamic effects on re-entering SNAP devices. The amount of aerodynamic heating as a function of body shape, size, and mode of entry was indicated. Test specimens yielded trajectory, aerodynamic heating data, heat distribution, and heat transfer of known bodies. IBM 7090 digital programs were utilized and so constructed that one digital code complemented the other, i.e., at any time during the re-entry period, the complete thermal history of the body is known. The test specimens consisted of lead bodies containing alkali metals, used as flaring material, and a larger titanium cylinder containing telemetry equipment to monitor the exterior and interior wall temperatures during re-entry. By judicious placement of transducer sensors, aerodynamic heating rates and mode of entry, i.e., tumbling, spinning, and/or stabilized, were determined. The lead bodies were consumed at high altitudes whereas the telemetry capsule survived re-entry. (auth)
Date: April 1, 1963
Creator: Hagis, W.
Partner: UNT Libraries Government Documents Department

NUCLEAR FUEL (OXIDE) CLAD THERMIONIC CONVERTERS. Quarterly Technical Progress Report, May 1 through July 31, 1963

Description: Fabrication of the components for the FDM-1 converter and its back-up device was completed. The FDM-1 converter was assembled, and preparations for testing were completed. Performance testing was initiated, and a total of 330 hours of operation above 1000 deg K in a cesium environment were logged. The peak emitter temperature reached was 2000 deg K with a thermionic output of nearly 2 watts/cm/sup 2/. Indications of a cesium leak were observed, and the device was shut down for examination. A 500-hour thermal endurance test of the clad fuel pellets was performed. A post-test examination was conducted, and no diffusion of UO/sub 2/ into the cladding was observed. A thermal conductivity test specimen was exposed to a temperature of 1550 deg C for 500 hours with the result that some intergranular diffusion was noted. The post-test examination of the vacuum emission test pellet was also completed. The design of the advanced double-diode thermionic converter utilizing the results of prior efforts was initiated. (auth)
Date: August 15, 1963
Partner: UNT Libraries Government Documents Department

SNAP 7 PROGRAM: TASK 8--STRONTIUM-90 FUELED THERMOELECTRIC GENERATOR DEVELOPMENT. Quarterly Progress Report No. 4, August 1, 1961-October 31, 1961

Description: Progress during the period includes completion of the SNAP 7C system tests, completion of safety analysis for the SNAP 7A and C systems, assembly and initial testing of SNAP 7A, assembly of a modified reliability model, and assembly of a 10-W generator. Other activities include completion of thermal and safety analyses for SNAP 7B and D generators and fuel processing for these generators. (J.R.D.)
Date: October 31, 1963
Creator: West, W.S.
Partner: UNT Libraries Government Documents Department

SNAP 7B--STRONTIUM-90 FUELED THERMOELECTRIC GENERATOR POWER SOURCE. THIRTY- WATT U.S. COAST GUARD AUTOMATIC LIGHT STATION. Final Report

Description: The objectives of the SNAP 7B program were to design, manufacture, test and deliver a thirty-watt electric generating system for a U. S. Coast Guard Automatic Light Station. This report describes the sixty-watt, strontium90 thermoelectric generator, the converter, the batteries, and the installation of the generator into the container. The electrical tests of the generator and of the system, the shock and vibration tests, and the tests at the environmental temperature extremes are discussed. (auth)
Date: June 1, 1963
Partner: UNT Libraries Government Documents Department

STRONTIUM-90 FUELED THERMOELECTRIC GENERATOR POWER SOURCE--FIVE-WATT U.S. NAVY WEATHER STATION. Final Report

Description: The SNAP-7C 10-watt Sr/sup 90/ thermoelectric generator, the converter, batteries, and weather station housing that were delivered to Antarctica in December 1961 are described. Thermoelectric analysis, thermal analysis, fuel form and shielding requirements, generator assembly, electrical system, operational tests, and environmental testing are discussed. (M.C.G.)
Date: October 31, 1963
Partner: UNT Libraries Government Documents Department

SNAP 7 PROGRAM--TASK 8--STRONTIUM-90 FUELED THERMOELECTRIC GENERATOR DEVELOPMENT. Quarterly Progress Report No. 7, May 1 through July 31, 1962

Description: The effort on SNAP 7A and 7C was confined to operating the reliability model. There were fluctuations in output power that can be attributed to variations in the operating parameters, plus an increase in the internal resistance. In the SNAP 7B project the second 60-watt generator was completed and has undergone the beginning-of-life (maximum input, helium gas) portion of the parametric tests. The performance was nearly identical to that of the first 60-watt generator. The unit will be used with the SNAP 7B system. The installation concept for the SNAP 7B system was approved by the U. S. Coast Guard. The generator is to be housed in a finned aluminum container that will provide the required radiator surface. This container will be filled with a water- ethylene glycol mixture that is necessary to transfer the heat from the generator into the container. The battery-converter compartment is an integral part of the container lid. During the time the entire SNAP 7D system was subjected to shock and vibratlon tests, no mechanical or functional deficiencies were detected. The required temperature tests followed the mechanical tests. During this period the complete system was operated at maximum intermediate and minimum temperatures. Design objectives were satisfied throughout the test. The SNAP 7D generator was fueled at Oak Ridge National Laboratory (ORNL) on June 12, 1962, with a total thermal input of 1435 watts. The iueled generator was returned and integrated with the system. The system was demonstrated and accepted on July 3, 1962. (auth)
Date: October 31, 1963
Creator: McDonald, W.A.
Partner: UNT Libraries Government Documents Department