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
Accelerator Applications
The division was organized to promote the advancement of knowledge of the use of particle accelerator technologies for nuclear and other applications. It focuses on production of neutrons and other particles, utilization of these particles for scientific or industrial purposes, such as the production or destruction of radionuclides significant to energy, medicine, defense or other endeavors, as well as imaging and diagnostics.
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.”
Drew E. Kornreich
Nuclear Technology | Volume 181 | Number 2 | February 2013 | Pages 282-302
Technical Paper | Reactor Safety | doi.org/10.13182/NT13-A15784
Articles are hosted by Taylor and Francis Online.
This work involved estimating the homogeneous metal-water mixture critical mass curves of 34 fissionable nuclides from thorium to einsteinium. Calculations were performed using the discrete ordinates code PARTISN with ENDF/B-VII.0 69-group cross sections. Sample MCNP5 test cases indicate reasonable agreement between the two transport codes. In general, the results confirmed that there are three "forms" of the critical mass curves: (a) the traditional curve most well known as characterizing the "big 3" nuclides (233U, 235U, 239Pu), where the minimum critical mass is found in a dilute solution; (b) a simple monotonic curve characterized by a monotonically increasing critical mass as water is added to the metal, where the minimum critical mass is a metal system; and (c) a hybrid curve where the shape is similar to the traditional curve but the minimum critical mass is the pure metal. In general, the traditional and monotonic curves follow the "odd-even" rule of thumb that a nuclide with an even Z and an odd A or vice versa will have a traditionally shaped curve and that the other nuclides will have a monotonically shaped curve. The violations of this rule of thumb, i.e., the hybrid curves, in the set of nuclides analyzed are comprised of 232U and 252Cf. Plutonium-236 is especially interesting because it is a traditionally shaped curve with the minimum critical mass in a relatively dilute solution, but it violates the "odd-even" rule of thumb.