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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.”
Masao Yamanaka, Cheol Ho Pyeon
Nuclear Science and Engineering | Volume 193 | Number 4 | April 2019 | Pages 404-416
Technical Paper | doi.org/10.1080/00295639.2018.1525978
Articles are hosted by Taylor and Francis Online.
To elucidate the accuracy of benchmarks of criticality at the Kyoto University Critical Assembly (KUCA), uncertainty analysis is conducted for manufacturing tolerances in highly enriched uranium (HEU) plates and modeling of core configurations in addition to nuclear data. For evaluation of eigenvalue bias, eigenvalue calculations are conducted using MCNP6.1 and SCALE6.2/KENO-VI together with ENDF/B-VII.1. The modeling of reference core configurations and material properties with average values is validated through a comparison between calculated and measured results. The uncertainty induced by nuclear data is evaluated with SCALE6.2/TSUNAMI-3D together with ENDF/B-VII.1 for sensitivity calculations and 56groupcov.7.1 for the covariance matrix. In the breakdown of the uncertainty induced by nuclear data, the impact of 235U shows significant dominance, about 900 pcm in hard and soft spectrum cores. Furthermore, uncertainty evaluation by manufacturing tolerances in HEU plates and reproducibility of control rod positions demonstrates that the impact of variation on measured reactivity is minor. Through experimental analyses, the index of accuracy in benchmark experiments of criticality is conducive to the reliability of benchmarks at KUCA.