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
Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
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.”
S. B. Degweker, Imre Pázsit
Nuclear Science and Engineering | Volume 168 | Number 3 | July 2011 | Pages 248-264
Technical Paper | doi.org/10.13182/NSE10-08
Articles are hosted by Taylor and Francis Online.
Invariant imbedding theory is an alternative formulation of particle transport theory. Until very recently, this theory was used only for deterministic calculations, i.e., for calculations of the first moment of the particle distribution. In a previous paper we set up a probability balance equation in the invariant imbedding approach. An equation was also obtained for the probability generating functional (pgfl) of reflected particles from which equations for the first- and second-order densities were derived. The approach was illustrated by a simple forward-backward scattering model with and without incorporating energy dependence to describe sputtering due to an external source of energetic particles on a medium. In this paper we extend these results to the case of a distributed internal source of particles. Among the possible applications, we discuss the problem of internal sputtering. We derive equations for the pgfl and the first- and second-order densities and show their connection with the external source problem. We treat the finite slab problem in addition to the semi-infinite slab geometry considered in our previous paper.