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Data sheets for PPO radioisotopic fuel

Description: PPO is the acronym for Pure Plutoniunn Oxide. The thermal energy of this fuel results from the radioactive decay of /sup 238/ Pu this energy is converted into usable electric power for space probe or other applications. The basic fuel module associated with the current MHW heat source is a PPO sphere 1.465 plus or minus 0.015 in. in dia and containing 100 plus or minus 2 thermal watts. The spheres are individually encapsulated and then assembled into geometric arrays to form the working heat source. The following document lists certain properties of PuO/sub 2/ with emphasis on behavior at the proposed operational conditions being discussed. Since many of the desired properties are still being determined, the information is preliminary in nature and will be revised periodically. This report is the first revision of LA-5160-MS (issued 2/ 73) and incorporates additional and more specific data. (auth)
Date: December 1, 1973
Creator: Keenan, T. K.; Kent, R. A.; Mulford, R. N. R. & Shupe, M. W.
Partner: UNT Libraries Government Documents Department

Radioisotope heat source development for an artificial heart device. Phase I. Final report

Description: Detailed parametric analyses of vented radioisotope heat sources were performed to arrive at a design optimized in weight, volume, and safety. The top rated system was a single-layer Hafnalloy heat source. Due to limited mechanical property, compatibility, and heat source test data available for this material, however, the three-layer Pt-20Rh/T-11I/Pt-20Rh design, which rated next highest, was selected as the baseline design. The heat source, 0.984 in. in dia by 1.795 in. long, contains 33.1 watts of electrorefined PuO/sub 2/ and weighs 0.62 lb. A nonselective pressure relief device/capillary assembly is connected between the noble metal liner and clad to allow venting of the helium gas generated by fuel decay and also to allow decay of the generated radon-220 gas to allowable levels. Pressure relief device tests verified its flow stability and fuel fines retention capability. Radon attenuation tests indicated a 0.001-in. I.D. capillary is required to reduce the radon levels to acceptable levels if it is assumed that all generated radon is released from the fuel. Safety design verification tests, including granite impact, bullet impact, crushing, fire, and postaccident oxidation, indicated both the baseline and Hafnalloy designs to survive all accident environments except one by containing the fuel simulant in at least one totally integral capsule component. Neither design was capable of containing the fuel simulant under a 2000 ft-lb 30-06 rifle bullet impact. Further studies in this area as related to heat source design are required. (auth)
Date: April 1, 1973
Creator: Lurie, H.
Partner: UNT Libraries Government Documents Department

Solubility study of strontium fuel compounds

Description: Strontium titanate, distrontium titanate, and strontium fluoride have been considered as isotopic fuels in thermoelectric generators for space and terrestrial applications. Evaluation of the radiobiological and radioecological effects of accidental release of /sup 90/Sr on land, in water, and in air requires a knowledge of the dissolution rates of the fuel in fresh water, salt water, and dilute HCl. Results of a study to investigate the behavior of these strontium fuel forms in the different test solutions are presented. (TFD)
Date: June 1, 1966
Creator: Gray, J. H.
Partner: UNT Libraries Government Documents Department

Mass spectrometric determination of $sup 18$O/$sup 16$O ratios to locate the source of oxygen in SNAP fuel capsule components

Description: The successful application of a mass spectrometric method to determine the source of oxygen diffusion into the container material of a radioisotopic fuel capsule is described. The source was chiefly the oxide fuel (/sup 238/PuO/ sub 2/) and not the atmosphere. This could be accomplished by determining the / sup 18/O//sup 16/O ratio in the tantalum alloy material, because the /sup 18/O content of the fuel had been reduced to minimize alpha -n reactions. The /sup 18/O//sup 16/O ratio was ~5.5 x 10/sup -4/ for fuel as compared with 2 x 10/sup - 3/ for air. The radiochemical method, based on an alpha -n reaction, could not be applied because of the very low alpha -particle flux in the liner material. (auth)
Date: February 1, 1974
Creator: Smith, M.E. & Waterbury, G.R.
Partner: UNT Libraries Government Documents Department

Thermal shock analysis of ceramic multihundred watt spheres

Description: The thermal fracture resistance of plutonia Multihundred Watt (MHW) fuel spheres was analyzed assuming boundary conditions of (1) constant heating or cooling rate for the sphere surface, (2) heating or cooling with a constant surface heat transfer coefficient at the sphere surface, and (3) heating or cooling the sphere surface solely by radiation. Thermal damage resistance (mechanical weakening) of MHW spheres was analyzed in terms of the fracture energy and crack system present in the fuel. Using available property data for porous PuO/sub 2/ between 400 and 1200 deg C, and estimating other properties from available data for UO/sub 2/ and ThO/sub 2/ the thermal shock conditions that cause fracture of the fuel sphere were estimated. Experimental values for the tensile fracture strength and the elastic modulus of the fuel as functions of temperature are presently not available and estimates were made of these properties. (auth)
Date: March 25, 1974
Creator: Tennery, V.J.
Partner: UNT Libraries Government Documents Department

Fabrication of granule and pellet heat sources from oxalate-based $sup 238$PuO$sub 2$

Description: Suitable fuel forms for radioisotopic thermoelectric generators are granules of high internal density (greater than 95 percent of theoretical) or geometric shapes (80 to 90 percent dense) such as pellets or spheres. Both forms can be made from calcined $sup 238$Pu(III) oxalate. The conditions for processing PuO$sub 2$ are controlled during fuel form fabrication to ensure pellet integrity; to control density, grain size, and porosity distribution; and to minimize the fraction of potentially respirable fines. The competing phenomena of expansion caused by radiation damage (including helium generation from radioactive decay of plutonium) and shrinkage caused by sintering must be controlled to assure dimensional stability. The variation of microstructure and related physical properties with process parameters is discussed. (auth)
Date: January 1, 1975
Creator: Bickford, D. F. & Rankin, D. T.
Partner: UNT Libraries Government Documents Department

Design, testing, and fabrication of heat sources for underwater application

Description: The sequence of events in the design, testing and fabrication of a radioisotopic heat source using available $sup 238$PuO$sub 2$ fuel that would be amenable to a Navy 0.5-W (electrical) Radioisotopic Thermoelectric Generator for undersea application is discussed. Various designs were considered as a function of heat leak in order to adopt the most desirable capsule for a volume- constrained application. Testing considerations are discussed for capsule compliance with IAEA/ENEA Safety Series 6 and 33 and 10 CFR 71. (auth)
Date: November 1, 1975
Creator: Luthy, D.F. & Anderson, C.G.
Partner: UNT Libraries Government Documents Department

Pacific Northwest Laboratory quarterly report to USERDA Advanced Nuclear Energy Systems, Space and Special Purposes Division, for July--September 1975

Description: Progress during July to October 1975 in research on radioisotope heat sources is reported. The design of the long-term $sup 90$SrF$sub 2$ compatibility tests has been finalized. The effect of thermal aging on the impact strength of Hastelloy C-4 is being evaluated using Charpy test specimens. The solubility of SrF$sub 2$ in seawater and demineralized water was determined at 23$sup 0$C. The equilibrium concentration of Sr in demineralized water is greatly influenced by the presence of fluoride impurities in the SrF$sub 2$, whereas in seawater the presence of fluoride impurities has little effect on the Sr concentration. The effect of impurity fluorides and decay product (ZrF$sub 4$) on the melting point of SrF$sub 2$ was determined using differential thermal analysis. The lowest melting point observed in the system containing SrF$sub 2$, ZrF$sub 4$ and impurity fluorides found in WESF $sup 90$SrF$sub 2$ was 851 +- 5$sup 0$C. Two reports on potential applications of isotopes were prepared, and theoretical work continued on the effect of source geometry on the radiation efficiency of $sup 137$CsCl capsules. (LCL)
Date: October 1, 1975
Creator: Fullam, H.T. & Harmon, K.M.
Partner: UNT Libraries Government Documents Department

Compatibility and stability of plutonia-238 base cermet fuel forms in refractory alloy containers at 1500$sup 0$ to 2000$sup 0$C

Description: The compatibility of two and stability of three plutonia-238 base cermet fuels were investigated at 1500 deg to 2000 deg C from which were well in excess of current RTGs. A Battelle-Columbus Laboratories plutonia-molybdenum cermet (BCL-PMC) developed as a precurser of the current PMC fuel form was investigated for stability at 1500 deg to 2000 deg C for times to 10,000 h. The thoria and molybdenum overcoated test specimens encapsulated in single W-25Re containers degraded with increasing time and temperature. The 1000-h specimens remained relatively intact; the 10,000-h specimens transported almost entirely to the container walls. The interim plutonia-thoria-molybdenum solid-solution cermet (SSC) fuel form lost from most to all of the molybdenum network in exposure at 1800 deg C for 5000 h. This behavior was inferior to the two PMC fuel forms. Comparative compatibility of the SSC was the same as the PMC. Behavior of the current reference PMC fuel form was equivalent to the BCL-PMC, with enhanced stability exhibited when exposed in TZM or Ta-10W inner containers. Exposures at 1500 deg C for 500 and 5000 h, 1800 deg C for 1000 and 5000 h, and 2000 deg C for 1000 h in double container semi-system test configurations resulted in increased fuel form degradation with increasing temperature and time. However, TZM liners with TZM, Mo-46Re, and W-25Re structural members provided excellent containment at all temperatures. (auth)
Date: September 1, 1973
Creator: Watrous, J. D. & Ferguson, W. E.
Partner: UNT Libraries Government Documents Department

Nuclear Heat Sources for Cryogenic Refrigerator Applications

Description: Spacecraft cryogenic refrigerators require thermal inputs on the order of 1000 W. First, the characteristics of solar-electric and radioisotope heat source systems for supplying this thermal input are compared. Then the design of a $sup 238$Pu heat source for this application is described, and equipment for shipping and handling the heat source is discussed. (LCL)
Date: June 1, 1975
Creator: Raab, Bernard; Schock, Alfred; King, William G.; Kline, Thomas & Russo, Frank A.
Partner: UNT Libraries Government Documents Department

ORNL isotopic power fuels quarterly report for period ending December 31, 1973

Description: Heat soak periods were completed on the remaining 49 couples of the compatibility matrix which was put on test in May 1973. Examination of the 18 couples which were taken off test in August 1973 was completed. The planned short-term ceramic compatibiliiy matrix exposures were completed, and optical microscope examinations were done. Experiments were started to develop fabrication techniques for preparation of an 11-couple compatibility matrix scheduled for FY 1974. The design of this matrix was finalized, and component procurement was started. Free energy calculations were made for the reactions of Cm/sub 2/O/sub 3/ fuel with Haynes 188, Ta-10% W, and TZM alloys and with beryllium. Measurements of the helium release characteristics of hot-pressed / sup 244 Cm/sub 2/O/sub 3/ were started at 500, 650, and 800 deg C. A vapor pressu re determination was run on curium metal in the temperature range from 900 to 1800 deg C. Vapor pressure measurements of/sup 244/Cm/sub 2/O/sub 3/ in the range from 1200 to 1600 deg C were begun these will continue next quarter. Examinations by x-ray diffraction were made on materials resulting from exposures of/sup 244/Cm/sub 2/O/sub 3/ to flowing seawater, boiling scawater, and dry air as well as on/sup 244/Cm/sub 2/O/sub 3/ sam ples taken at various stages in the fuel forming process. The equipment which will be used for emissivity measurements was improved and checked with nonradioactive samples. Observations of two 25-W//sup 244/Cm/sub 2/O/sub 3/ pellets stored in argon ond one 25-W/sup 244/Cm/sub 2/O/sub 3/ pellet stored in dry air continued. A /sup 244/Cm/sub 2/O/ sub 3/ pellet was leac hed with boiling distilled water and the rate of/sup 244/ Cm loss measured. Calculational studies of /sup 244/Cm yields and isotopic abundances from various types of reactor operations were continued. A study of the potentinl fur criticality problems in/sup …
Date: February 1, 1974
Creator: Lamb, E.
Partner: UNT Libraries Government Documents Department

Savannah River Laboratory monthly report: {sup 238}Pu fuel form processes

Description: In direct-strike {sup 238}PuO{sub 2}, agglomeration occurs in the oxalate precipitate and is unaffected by washing agent or calcining temperature. The evaluation of an automatic pulverizer-classifier for the PuFF Facility was begun. Difference between the mini-hot press at SRL and the LASL full-scale hot press require higher pressures to be used at SRL to obtain the density specified for PPO. Hot-pressed density was found to vary with applied pressure and, to a lesser extent, with size of feed. The new contained metallograph has been installed. A wire saw has been placed in containment for precise cutting of PPO pellets. The scanning microscope was mounted within the glove boxes.
Date: April 1, 1974
Partner: UNT Libraries Government Documents Department
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