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
Aerospace Nuclear Science & Technology
Organized to promote the advancement of knowledge in the use of nuclear science and technologies in the aerospace application. Specialized nuclear-based technologies and applications are needed to advance the state-of-the-art in aerospace design, engineering and operations to explore planetary bodies in our solar system and beyond, plus enhance the safety of air travel, especially high speed air travel. Areas of interest will include but are not limited to the creation of nuclear-based power and propulsion systems, multifunctional materials to protect humans and electronic components from atmospheric, space, and nuclear power system radiation, human factor strategies for the safety and reliable operation of nuclear power and propulsion plants by non-specialized personnel and more.
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.”
A. F. Henry
Nuclear Science and Engineering | Volume 20 | Number 3 | November 1964 | Pages 338-351
Technical Paper | doi.org/10.13182/NSE64-A19579
Articles are hosted by Taylor and Francis Online.
For a large power reactor it appears possible to describe nonseparable space-time kinetics transients in terms of a particular set of spatial harmonics to be called inhour modes. These modes are defined as a subset of the period modes obtained by assuming a separable time variation ewt for all variables in the source-free, time-dependent neutron and neutron-precursor equations. Their use is appropriate whenever details of the neutron energy and angular behavior are not required. Inhour modes are shown to occur in clusters of seven, the seven eigenvalues of a given cluster being obtained as the roots of an inhour equation appropriate to the cluster. The neutron flux shapes associated with a particular cluster of seven modes are all approximately the same. It is shown that if these shapes are assumed to be identical, certain useful orthogonality relations and certain identities involving the roots of the inhour formula for a given cluster are obtained. Use of these results simplifies the extension of the conventional equations of reactor kinetics to the nonseparable case. Inhour modes are also useful in analyzing certain experiments involving subcritical assemblies. As an illustration, application to the source-jerk and pulsed-source experiments is made.