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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.”
Bobbi Riedel, Christopher M. Perfetti, Forrest B. Brown
Nuclear Science and Engineering | Volume 198 | Number 6 | June 2024 | Pages 1276-1287
Research Article | doi.org/10.1080/00295639.2023.2249787
Articles are hosted by Taylor and Francis Online.
The goal of this study is to evaluate the accuracy of different upper subcritical limit (USL) calculational methods for loosely coupled and novel neutronic systems. This study varied the separation distance over five center-to-center separation distance intervals for four loosely coupled models and explored seven single-system neutronic models. Each of these 27 systems was simulated using MCNP6.2 with 200 randomly perturbed, continuous-energy ENDF/B-VII.1 cross-section files that are in the TENDL 2019 library. The distribution of the values from these perturbed runs was used to calculate stochastic 99/99 USL values for each model iteration. USLs were also estimated for these 20 systems using the Whisper 1.1 code, and the Whisper-identified relevant benchmarks were used to further analyze the relationship between the region-wise USL calculation and the overall system USL calculations. Sensitivity data files were produced using MCNP6.2 and then used with the Oak Ridge National Laboratory TSURFER and USLSTATS methods to estimate USLs for a cross-method USL comparison. A windowing study was performed when using the USLSTATS method to determine the efficacy of the method using datasets with differing degrees of similarity to the given application case. The results show that USLs for each of the loosely coupled system models were higher USLs than the calculated stochastic USLs. The single-system uranium models also displayed a consistently lower stochastic USL as compared to the USL calculational methods, while the single-system plutonium models showed close agreement between the stochastic USLs and the other USL calculational methods.