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Isotopes & Radiation
Members are devoted to applying nuclear science and engineering technologies involving isotopes, radiation applications, and associated equipment in scientific research, development, and industrial processes. Their interests lie primarily in education, industrial uses, biology, medicine, and health physics. Division committees include Analytical Applications of Isotopes and Radiation, Biology and Medicine, Radiation Applications, Radiation Sources and Detection, and Thermal Power Sources.
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ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
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The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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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.”
Jeffrey C. King, Leonardo de Holanda Mencarini
Nuclear Technology | Volume 208 | Number 7 | July 2022 | Pages 1137-1148
Technical Paper | doi.org/10.1080/00295450.2021.2004870
Articles are hosted by Taylor and Francis Online.
A low-enriched-uranium (LEU)–fueled space reactor could avoid the security and proliferation concerns inherent with highly enriched uranium (HEU)–fueled space nuclear reactors. Recent LEU-fueled space reactor designs include a moderator to reduce the size and mass of the reactor core. This paper considers shadow shield options for an unmoderated HEU-fueled space reactor and a moderated LEU-fueled space reactor. Both reactors are kilowatt-class reactors, producing 15 kW(thermal) of thermal power over a 5-year operational lifetime. Based on the shielding required to meet established dose limits [a neutron fluence of less than 1014 n/cm2 (1 MeV equivalent in silicon) and a gamma-ray dose of less then 1 Mrad in silicon], the moderated LEU-fueled space reactor will require a thicker shadow shield than the unmoderated HEU-fueled space reactor. The thinner reflector of the moderated LEU-fueled reactor results in more neutrons reaching the shadow shield at higher energies compared to the unmoderated HEU-fueled reactor. The presence of a significant reflector in most space reactor designs means that the core spectrum is relatively unimportant in terms of shadow shield design, as the reflector thickness has a much stronger impact on the neutrons and gamma rays reaching the shadow shield. Based on the results presented in this paper, the mass optimization of moderated LEU-fueled space nuclear reactors should always consider the coupled effects of the core, the reflector, and the shielding.