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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.”
J. Ligou
Nuclear Science and Engineering | Volume 50 | Number 2 | February 1973 | Pages 135-146
Technical Paper | doi.org/10.13182/NSE73-A23237
Articles are hosted by Taylor and Francis Online.
Polynomial approximations in space are used for solving the integral transport equations for multilayers systems, in one dimensional spherical or cylindrical geometry with scattering anisotropy. These polynomial approximations are applied to the neutron sources (collided neutrons) in each layer, in such a way that the mean quadratic error is a minimum. The form of this approximation allows a less complicated treatment of the anisotropic components of the collided neutron sources than the usual approach (collision probabilities for uniform sources). In order to reduce the number of necessary integral equations when the scattering anisotropy is present, some differential equations relating the spherical harmonics components of the angular flux are used. This is very useful from a numerical point of view, especially when polynomial approximations in space are introduced. A very important link between the scattering anisotropy and the degree of polynomial approximations is also derived. Based on this method the SHADOK code was written. Several numerical examples dealing with multigroup calculations of fast critical assemblies for spherical geometry (FRO-GODIVA-TOPSY-ZPR.43/8) are given. The results show that (a) the large optical dimensions are not a problem for this improved integral method, (b) the scattering.anisotropy (at least PI) does not increase the time of computation, and (c) the heterogeneous systems (reflected cores) can be calculated easily. The calculations with the proposed method are considerably faster than those of the SN method.