ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Division Spotlight
Human Factors, Instrumentation & Controls
Improving task performance, system reliability, system and personnel safety, efficiency, and effectiveness are the division's main objectives. Its major areas of interest include task design, procedures, training, instrument and control layout and placement, stress control, anthropometrics, psychological input, and motivation.
Meeting Spotlight
ANS Student Conference 2025
April 3–5, 2025
Albuquerque, NM|The University of New Mexico
Standards Program
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!
Latest Magazine Issues
Apr 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
May 2025
Nuclear Technology
April 2025
Fusion Science and Technology
Latest News
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.”
Harvey J. Amster, K. Cheuk Chan
Nuclear Science and Engineering | Volume 61 | Number 3 | November 1976 | Pages 388-398
Technical Paper | doi.org/10.13182/NSE76-A26925
Articles are hosted by Taylor and Francis Online.
An elementary function for the collision density of neutrons slowing down from a plane source in hydrogen is synthesized through a set of schemes incorporating several known explicit features of the exact solution. First, the Marshak distribution is assigned a distorted lethargy variable that makes its zeroth and second spatial moments exact at all lethargies while automatically preserving its detailed accuracy at large lethargies. The same exact moments are also required of a specific functional form able to assume the correct spatial dependence at small lethargies. Then, a linear combination of these functions is constructed with coefficients making the two moments and the first spatial derivative at the source plane exact at all lethargies. The resulting distribution automatically becomes correct at both lethargy extremes. In addition, a remaining lethargy-dependent parameter makes the fourth spatial moment exact at all lethargies except within a finite interval of intermediate values, where its error must reach a maximum of 2.7%. Extraneous roots from multiple bifurcations of the parameter are identified by their unphysical implications. For computational simplicity, both this parameter and the incorporated function for the exact spatial derivative at the source plane are replaced by fitted elementary functions. The resulting expression for the collision density agrees very closely with McInerney's Monte Carlo calculations. Some extensions are described in a separate Note.