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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.”
Michael E. Rising, Todd S. Palmer
Nuclear Science and Engineering | Volume 160 | Number 3 | November 2008 | Pages 284-301
Technical Paper | doi.org/10.13182/NSE160-284
Articles are hosted by Taylor and Francis Online.
Characteristic methods are widely known to be very accurate approaches to the solution of numerical transport problems. These methods are most often used for neutron transport applications (i.e., lattice physics calculations) where spatial cells are of intermediate optical thickness [O(1) to O(100) mean free paths, depending on the energy group] and materials are not exceptionally highly scattering (scattering ratios < 0.999). There has been interest in using characteristic methods for radiative transfer applications, which often involve very optically thick and diffusive regions. Previous work has involved analyses of families of Cartesian geometry characteristic methods in optically thick and diffusive regions. There is a significant body of work in the Russian literature on curvilinear geometry characteristic methods, but very few analyses of their behavior in thick diffusive regions have been published. In this paper we develop two new members of a family of one-dimensional spherical geometry characteristic methods - the method of tubes. These new methods are similar to traditional slab geometry characteristics methods in that they utilize spatial moments of the transport equation in each cell to generate the data used in the representation of the total source (scattering source plus external source). We present the results of an asymptotic analysis of these methods to predict their behavior in the thick diffusion limit, and we compare these predictions with numerical results from several test problems. This analysis shows that the constant source (step) method behaves very poorly in the diffusion limit, but that the linear source method is accurate in this physical regime.