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
2026 Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
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
Dec 2025
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
January 2026
Nuclear Technology
December 2025
Fusion Science and Technology
November 2025
Latest News
What’s the most difficult question you’ve been asked as a maintenance instructor?
Blye Widmar
"Where are the prints?!"
This was the final question in an onslaught of verbal feedback, comments, and critiques I received from my students back in 2019. I had two years of instructor experience and was teaching a class that had been meticulously rehearsed in preparation for an accreditation visit. I knew the training material well and transferred that knowledge effectively enough for all the students to pass the class. As we wrapped up, I asked the students how they felt about my first big system-level class, and they did not hold back.
“Why was the exam from memory when we don’t work from memory in the plant?” “Why didn’t we refer to the vendor documents?” “Why didn’t we practice more on the mock-up?” And so on.
B. R. Merk, D. G. Cacuci
Nuclear Science and Engineering | Volume 151 | Number 2 | October 2005 | Pages 184-193
Technical Paper | doi.org/10.13182/NSE05-A2539
Articles are hosted by Taylor and Francis Online.
The derivation of a closed-form expression is presented for a three-timescale approximation of the point-kinetics equations with two effective groups of delayed neutrons. The results produced by this three-scale approximation are shown to be practically as accurate as the numerical results produced by the Kaganove-type algorithms used in production codes, yet at significantly less cost in computational time and resources. Potential uses of this approximation for increasing the efficiency of production codes for computing the space-time distribution of neutrons in reactors are also indicated.