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ANS Student Conference 2025
April 3–5, 2025
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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.”
M. Assawaroongruengchot, G. Marleau
Nuclear Science and Engineering | Volume 157 | Number 1 | September 2007 | Pages 30-50
Technical Paper | doi.org/10.13182/NSE07-A2711
Articles are hosted by Taylor and Francis Online.
Generalized perturbation theory (GPT) is a technique used for the estimation of small changes in performance functionals, such as linear reaction rate ratios, eigenvalues, power density, etc., affected by small variations in reactor core compositions. Here, a GPT algorithm is developed for the multigroup integral neutron transport problems in two-dimensional fuel assemblies with isotropic scattering. We then use the relationship between the generalized flux importance and generalized source importance functions to transform the generalized flux importance transport equations into the integrodifferential equations for the generalized adjoints. The resulting adjoint and generalized adjoint transport equations are then solved using the method of cyclic characteristics (MOCC). Because of the presence of negative adjoint sources, a coupled flux biasing/decontamination scheme is applied to make the generalized adjoint functions positive in such a way that it can be used for the multigroup rebalance technique. After convergence is reached, the decontamination procedure extracts from the generalized adjoints the component parallel to the adjoint function. Three types of biasing/decontamination schemes are investigated in the study. To demonstrate the efficiency of our solution algorithms, calculations are performed on 17 × 17 pressurized water reactor and 37-pin Canada deuterium uranium reactor (CANDU) lattices. Numerical comparisons of the generalized adjoint functions and GPT estimates using the MOCC and collision probability method are presented as well as sensitivity coefficients of nuclide densities.
