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The design of a source to simulate the gamma-ray spectrum emitted by a radioisotope thermoelectric generatorA simulated source was designed to duplicate the gamma spectrum of a uniform cylindrical 2200-watt Pu02 radioisotope thermoelectric generator containing 81% Pu-238 and 1.2 ppm Pu-236. Gamma rays from the decay of Pu-238, Am-241, Pu-239, and the 0-18(alpha,n)Ne-21 reaction were catalogued in broad energy groups. Two 46- and one 22-mc Th-228 sources provided simulation at various times in the life of the fuel capsule up to 18 years, which covers the time span of an outer planet mission. Emission from Th-228 represents the overwhelming contribution of the gamma spectrum after the first few years. The sources, in the form of 13-inch rods, were placed in a concentric hole in a cylinder of depleted uranium, which provided shielding equivalent to the self-shielding of the fuel capsule. The thickness of the U-238 cylinder (0.55cm) was determined by Monte Carlo calculations to insure that the spectrum emerging from the simulated source matched that of the fuel capsule.
Document ID
Document Type
Conference Paper
Reier, M. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 6, 2013
Publication Date
January 1, 1972
Publication Information
Publication: Proc. of the Natl. Symp. on Nat. and Manmade Radiation in Space
Subject Category
Distribution Limits
Work of the US Gov. Public Use Permitted.

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IDRelationTitle19720009951Analytic PrimaryProceedings of the National Symposium on Natural and Manmade Radiation in Space