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Operations & Power
Members focus on the dissemination of knowledge and information in the area of power reactors with particular application to the production of electric power and process heat. The division sponsors meetings on the coverage of applied nuclear science and engineering as related to power plants, non-power reactors, and other nuclear facilities. It encourages and assists with the dissemination of knowledge pertinent to the safe and efficient operation of nuclear facilities through professional staff development, information exchange, and supporting the generation of viable solutions to current issues.
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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.”
Dean Wang
Nuclear Science and Engineering | Volume 193 | Number 12 | December 2019 | Pages 1339-1354
Technical Paper | doi.org/10.1080/00295639.2019.1638660
Articles are hosted by Taylor and Francis Online.
The SN transport equation asymptotically tends to an equivalent diffusion equation in the limit of optically thick systems with small absorption and sources. A spatial discretization of the SN equation is of practical interest if it possesses the optically thick diffusion limit. Such a numerical scheme will yield accurate solutions for diffusive problems if the spatial mesh size is thin with respect to a diffusion length, whereas the mesh cells are thick in terms of a mean free path. Many spatial discretization methods have been developed for the SN transport equation, but only a few of them can obtain the thick diffusion limit under certain conditions. This paper presents a theoretical result that simply states that the mesh size required for a finite difference scheme to attain the diffusion limit is , where is the order of accuracy of spatial discretization, is the “diffusion” mesh size that can be many mean free paths thick, and is a small positive scaling parameter that can be defined as the ratio of a particle mean free path to a characteristic scale length of the system. Numerical results for schemes such as the Diamond Difference method, Step Characteristic method, Step Difference method, Second-Order Upwind method, and Lax-Friedrichs Weighted Essentially Non-Oscillatory method of the third order (LF-WENO3) are presented that demonstrate the validity and accuracy of our analysis.