Author:
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Category :
Languages : en
Pages : 10

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Author: D. E. Thomas
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ISBN:
Category : Nuclear fuels
Languages : en
Pages : 368

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Category :
Languages : en
Pages : 17

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Author: Robert L. Mead
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ISBN:
Category : Radioisotopes
Languages : en
Pages : 44

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Author: R. C. Erdmann
Publisher:
ISBN:
Category : Radioisotopes
Languages : en
Pages : 29

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The results of the study show that lightweight radioisotope heat sources can be considered for use undersea with little shielding necessary for electronics packages in close proximity to the heat source. Acceptable integrated electronic dose levels of 10 to the 7th power rads for gamma irradiation and 10,000 reps for neutron bombardment were obtained for extended mission times for the three isotopes considered. It is unnecessary to shield the isotope 210Po for electronic protection. However, use would be restricted because of its short half-life and this isotope could present special heat management problems not encountered with either 60Co or 244Cm. For 244Cm and 60Co it was found that the shield around the electronics package becomes important due to the strong back scattering effect of neutrons and gammas from the surrounding seawater. The 244Cm heat source appears to require less shielding to electronics level and would therefore take up less volume in the undersea system than the 60Co heat source.

Author: U.S. Atomic Energy Commission
Publisher:
ISBN:
Category : Radioisotopes
Languages : en
Pages : 52

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Author:
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Category :
Languages : en
Pages :

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For the radioisotopes with half-lives over a year, only eight appear to be obtainable in the foreseeable future. The fission products, strontium-90, cesium-137, and promethium-147, exist in wastes from reactor processing, diluted with enormous volumes of other elements and salts. Among those isotopes producible by irradiation of special target materials (cobalt-60, uranium-232, plutonium-238, and curium-244) cobalt-60, though easy to produce, requires a special design for the heat source generator because much of its emitted energy is penetrating gamma radiation. Cobalt-60 appears, therefore, to be rather limited in its prospects for use. Plutonium-238 is favored as a heat source because of its long half-line and no need for special shielding. However, its projected high cost, scarcity, and biological hazard encourages the search for a competitive material. When plutonium assumes a significant place as a recycled fuel in thermal reactors for power production, curium-244 can then become available at costs below that for plutonium-238. Curiunm-244 has five times the specific power of plutonium-238 and appears to be just as easy to handle. Promethium-147, although probably on the ''short end'' of the half-life scale, can be considered for some uses as a substitute for plutonium-238. Although the factors of availability, gamma activity, and biological characteristics are unfavorable, the strongly points for uranium-232 (and thorium-228) are extremely high power densities, relatively low expected costs, and unusually long-life nearly constant heat output. The short life of thorium-228 (1.9 years) is a disadvantage. This study indicates that aged promethium-147 should be receiving more serious attention as a heat source.

Author: K. W. Foster
Publisher:
ISBN:
Category : Irradiation
Languages : en
Pages : 16

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Author: C. A. Rohrmann
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Category : Isotopic power generators
Languages : en
Pages : 116

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Author: Los Alamos Scientific Laboratory
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ISBN:
Category : Nuclear industry
Languages : en
Pages : 42

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