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
Nuclear Nonproliferation Policy
The mission of the Nuclear Nonproliferation Policy Division (NNPD) is to promote the peaceful use of nuclear technology while simultaneously preventing the diversion and misuse of nuclear material and technology through appropriate safeguards and security, and promotion of nuclear nonproliferation policies. To achieve this mission, the objectives of the NNPD are to: Promote policy that discourages the proliferation of nuclear technology and material to inappropriate entities. Provide information to ANS members, the technical community at large, opinion leaders, and decision makers to improve their understanding of nuclear nonproliferation issues. Become a recognized technical resource on nuclear nonproliferation, safeguards, and security issues. Serve as the integration and coordination body for nuclear nonproliferation activities for the ANS. Work cooperatively with other ANS divisions to achieve these objective nonproliferation policies.
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
Mar 2025
Jul 2024
Latest Journal Issues
Nuclear Science and Engineering
March 2025
Nuclear Technology
Fusion Science and Technology
April 2025
Latest News
Nuclear News 40 Under 40 discuss the future of nuclear
Seven members of the inaugural Nuclear News 40 Under 40 came together on March 4 to discuss the current state of nuclear energy and what the future might hold for science, industry, and the public in terms of nuclear development.
To hear more insights from this talented group of young professionals, watch the “40 Under 40 Roundtable: Perspectives from Nuclear’s Rising Stars” on the ANS website.
Harvey Amster
Nuclear Science and Engineering | Volume 21 | Number 2 | February 1965 | Pages 206-216
Technical Paper | doi.org/10.13182/NSE65-A21045
Articles are hosted by Taylor and Francis Online.
The spatially-independent spectrum of neutrons slowing down in an infinite medium with constant cross sections is calculated from both the Laplace transform exactitude (LTE) and a generalized synethtic kernel approximation (SKA). The fluxes are expressed as sums of exponentials in lethargy and compared asymptotically. For hydrogenous mixtures, two of an infinite number of terms from the LTE are non-oscillatory, both dominate all others at large lethargies, and one vanishes whenever hydrogen is a sole or missing constituent. The SKA yields a solution consisting of as many exponentials as isotopes present. The longest-lived terms are generally most accurate, but even the dominant one can be exact only if there is no absorption or if hydrogen is the sole moderator. For binary mixtures, both terms in the SKA fluxes are non-oscillatory, and the secondary one vanishes for the same concentrations that make the corresponding term in the LTE vanish. Analytic expressions for errors in the asymptotic flux from the SKAs are given as a function of lethargy, all the cross sections, and masses. For every instance observed, the exact asymptotic flux is bounded on different sides by values from the Greuling-Goertzel and Selengut-Goertzel SKAs.