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Reactor Physics
The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
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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.”
Masaki Goto, Tadafumi Sano, Kunihiro Nakajima, Takashi Kanda, Atsushi Sakon, Kengo Hashimoto
Nuclear Science and Engineering | Volume 197 | Number 8 | August 2023 | Pages 1814-1822
Technical papers from: PHYSOR 2022 | doi.org/10.1080/00295639.2022.2143707
Articles are hosted by Taylor and Francis Online.
Feynman-α analyses for a critical state and several subcritical states of the UTR-KINKI reactor have been carried out using two Bi14Ge3O12 (BGO) gamma-ray detectors free from radioactivation of the scintillator. As a statistical index of the analyses, the covariance-to-mean ratio of gamma counts between these detectors instead of the variance-to-mean ratio of each of the detectors is employed to get rid of a large negative correlation originating from the counting loss of a signal processing circuit. In the gate width dependence of the covariance-to-mean ratio measured at each reactor state, not only a familiar neutron-correlation component but also another small positive correlation between prompt gammas can clearly be observed. The prompt-neutron decay constant α determined considering the positive gamma correlation agrees very well with that obtained from a conventional Feynman-α analysis based on neutron detection. Neglecting the gamma correlation term, the decay constant is much overestimated with an increase in subcriticality, and the maximum overestimation reaches about 24% at a shutdown state with a subcriticality of 1.49%Δk/k.