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.
Explore membership for yourself or for your organization.
Conference Spotlight
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
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
Nov 2025
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
December 2025
Nuclear Technology
November 2025
Fusion Science and Technology
Latest News
Nuclear News 40 Under 40—2025
Last year, we proudly launched the inaugural Nuclear News 40 Under 40 list to shine a spotlight on the exceptional young professionals driving the nuclear sector forward as the nuclear community faces a dramatic generational shift. We weren’t sure how a second list would go over, but once again, our members resoundingly answered the call, confirming what we already knew: The nuclear community is bursting with vision, talent, and extraordinary dedication.
G. R. Keepin
Nuclear Science and Engineering | Volume 5 | Number 2 | February 1959 | Pages 132-136
Technical Paper | doi.org/10.13182/NSE59-A25566
Articles are hosted by Taylor and Francis Online.
Reactor period-reactivity relations may be determined directly by numerical integration of “prompt-burst” neutron decay data without analysis into delayed neutron period and abundance values. Period-reactivity relations obtained by this method for six fissile species are compared with the corresponding relations calculated from the customary “inhour” equation. Application of this method to mixtures of fissile materials in various neutron energy spectra is discussed.
