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
Apr 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
May 2025
Nuclear Technology
April 2025
Fusion Science and Technology
Latest News
First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
K. M. Case, Joel H. Ferziger, P. F. Zweifel
Nuclear Science and Engineering | Volume 10 | Number 4 | August 1961 | Pages 352-356
doi.org/10.13182/NSE61-A15377
Articles are hosted by Taylor and Francis Online.
It is first shown that the results of “asymptotic reactor theory” may be derived simply from the condition that an infinite medium rather than the correct finite medium diffusion equation be used to describe the thermal neutron flux in a reactor. In an asymptotic (bare, homogeneous, thermal) reactor, it is possible to describe the thermal flux through such an equation if the kernel of the infinite medium equation is defined properly, even when the reactor is not “large.” The relation between the kernels of the two equations is explicitly derived, and the conditions examined under which the kernel of the infinite medium equation can be interpreted physically as the Green's function of the infinite medium slowing-down problem. It is found that this interpretation is not restricted to the case in which the finite medium, slowing-down problem can be treated accurately by diffusion theory. Rather, the restriction is that the “asymptotic” portion of the flux give a reasonably accurate description of the finite medium Green's function. Thus, the use of transport kernels in asymptotic reactor theory is meaningful, a result which has been observed, but not explained, by a number of authors.