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Title: EFFECTS OF THE REENTRY ENVIRONMENT ON RADIOISOTOPE HEAT SOURCES.

Authors:
Publication Date:
Research Org.:
Sandia Corp., Albuquerque, N. Mex.
OSTI Identifier:
4505297
Report Number(s):
SC-DC-68-2161; CONF-681002-1
NSA Number:
NSA-22-042976
DOE Contract Number:
AT(29-1)-789
Resource Type:
Technical Report
Resource Relation:
Other Information: From Nuclear Metallurgical Symposium on Materials for Radioisotope Heat Sources, Gatlinburg, Tenn. UNCL. Orig. Receipt Date: 31-DEC-68
Country of Publication:
United States
Language:
English
Subject:
N24410* -Engineering-Isotope Technology-Power Sources; ATMOSPHERE; BATTERIES; POWER PLANTS; RADIOISOTOPES; RE-ENTRY; SAFETY; SNAP BATTERIES; SPACE FLIGHT; SPACE VEHICLES; NESDPS Office of Nuclear Energy Space and Defense Power Systems; HEAT SOURCES/reentry of radioisotope, environmental effects on intact; SYSTEMS FOR NUCLEAR AUXILIARY POWER (SNAP)/reentry of radioisotope heat sources after mission aborts, environmental effects on intact

Citation Formats

McAlees, S. Jr.. EFFECTS OF THE REENTRY ENVIRONMENT ON RADIOISOTOPE HEAT SOURCES.. United States: N. p., 1968. Web. doi:10.2172/4505297.
McAlees, S. Jr.. EFFECTS OF THE REENTRY ENVIRONMENT ON RADIOISOTOPE HEAT SOURCES.. United States. doi:10.2172/4505297.
McAlees, S. Jr.. Mon . "EFFECTS OF THE REENTRY ENVIRONMENT ON RADIOISOTOPE HEAT SOURCES.". United States. doi:10.2172/4505297. https://www.osti.gov/servlets/purl/4505297.
@article{osti_4505297,
title = {EFFECTS OF THE REENTRY ENVIRONMENT ON RADIOISOTOPE HEAT SOURCES.},
author = {McAlees, S. Jr.},
abstractNote = {},
doi = {10.2172/4505297},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 1968},
month = {Mon Jan 01 00:00:00 EST 1968}
}

Technical Report:

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  • A most promising approach to the isotope reentry problem, with particular application to large, high powered systems, is high altitude dispersion and reentry of individual capsules each surrounded by its own protection against aerodynamic heating. Although much effort has been directed to the development of reentry protection materials during the past fifteen years, the resulting materials are not satisfactory for isotope capsules. Preliminary analyses and experimental tests demonstrated the feasibility of composite ablators specifically suited to isotope protection. These composites consist of sublimating salt contained within a porous metal matrix. In the experimental program, cylinders of AlF/sub 3/-Ni were fabricatedmore » and tested in an arc-jet wind tunnel at simulated reentry conditions. The AlF/sub 3/-Ni composites were shown to be excellent reentry protection materials combining thermal stability at 1500 to 1800/sup 0/F, reentry temperatures (at the protected capsule surface) not exceeding 2050 to 2200/sup 0/F, large heat absorption and reradiating capability, and reasonable structural integrity.« less
  • Diffusion of helium in /sup 238/PuO/sub 2/ fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trappingmore » along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel.« less