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Nuclear Criticality Safety
NCSD provides communication among nuclear criticality safety professionals through the development of standards, the evolution of training methods and materials, the presentation of technical data and procedures, and the creation of specialty publications. In these ways, the division furthers the exchange of technical information on nuclear criticality safety with the ultimate goal of promoting the safe handling of fissionable materials outside reactors.
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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.”
Samuel Carmona, Shimon Yiftah
Nuclear Technology | Volume 71 | Number 1 | October 1985 | Pages 289-295
Technical Paper | Material | doi.org/10.13182/NT85-A33727
Articles are hosted by Taylor and Francis Online.
Complete evaluations of the (n,2n) and (n,3n) reaction cross sections were carried out for the stable isotopes of lead and for natural lead, that element being a potential neutron amplifier for fusion blankets. The method of computation used is based on the Segev simple formalism for compound nucleus decay without branching. This method, which was already checked for 204Pb, was used for cross-section computation for all other stable lead isotopes. From these results, evaluated cross sections could be derived for natural lead. The results of the evaluations were in good agreement with experimental data. Small discrepancies with the measured data for 204Pb, 207Pb, and 208Pb at low excitation energies above threshold are overcome through the introduction of an “effective” threshold energy slightly higher than the real one. This single correction is sufficient for matching the shape of the evaluated curves to the measured data over the entire energy range for the second neutron emission.
