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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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General Kenneth Nichols and the Manhattan Project
Nichols
The Oak Ridger has published the latest in a series of articles about General Kenneth D. Nichols, the Manhattan Project, and the 1954 Atomic Energy Act. The series has been produced by Nichols’ grandniece Barbara Rogers Scollin and Oak Ridge (Tenn.) city historian David Ray Smith. Gen. Nichols (1907–2000) was the district engineer for the Manhattan Engineer District during the Manhattan Project.
As Smith and Scollin explain, Nichols “had supervision of the research and development connected with, and the design, construction, and operation of, all plants required to produce plutonium-239 and uranium-235, including the construction of the towns of Oak Ridge, Tennessee, and Richland, Washington. The responsibility of his position was massive as he oversaw a workforce of both military and civilian personnel of approximately 125,000; his Oak Ridge office became the center of the wartime atomic energy’s activities.”
R. K. Lane, L. W. Nordheim, J. B. Sampson
Nuclear Science and Engineering | Volume 14 | Number 4 | December 1962 | Pages 390-396
Technical Paper | doi.org/10.13182/NSE62-A26247
Articles are hosted by Taylor and Francis Online.
The problem of resonance absorption is investigated for materials in which the absorber is lumped in small grains imbedded in a matrix of moderator. The point of departure is to take the grains themselves as the fundamental elements in heterogeneous geometry. It is important to treat correctly the mutual shielding between the grains, that is, the Dancoff correction. Introduction of this correction solves immediately the case of macroscopically homogeneous assemblies. The result can be expressed in terms of “shielded” cross sections for the lumped absorber. Utilization of this concept permits also the treatment of additional macroscopic heterogeneities. Existing calculational methods can be employed if the macroscopic heterogeneities are treated with the help of the equivalence relations, and this procedure permits an adequate comparison between the grain structured and homogeneous compounds. Numerical examples are given in Section IV. The average shielding is nearly linear in the grain size. For grains of ThO2 in a graphite matrix, the reduction is about 15% for grains of 0.06 cm diam. On the other hand, the temperature derivative of the resonance integral is increased slightly, particularly at higher temperatures. One can, therefore, either maintain the Doppler coefficient of reactivity with a reduced resonance absorption or increase the Doppler coefficient for the same resonance absorption.