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
Education, Training & Workforce Development
The Education, Training & Workforce Development Division provides communication among the academic, industrial, and governmental communities through the exchange of views and information on matters related to education, training and workforce development in nuclear and radiological science, engineering, and technology. Industry leaders, education and training professionals, and interested students work together through Society-sponsored meetings and publications, to enrich their professional development, to educate the general public, and to advance nuclear and radiological science and engineering.
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.
Satoru Katsuragi
Nuclear Science and Engineering | Volume 13 | Number 3 | July 1962 | Pages 215-229
Technical Paper | doi.org/10.13182/NSE62-A26156
Articles are hosted by Taylor and Francis Online.
The thermalization of neutrons in a finite medium is investigated to give a foundation for reactor calculations. The theory has been made free from the assumption that the energy spectrum of the flux is uniform throughout the medium. The flux is composed of several components, each having a definite spectrum and an associated diffusion length which are to be determined as an eigenmode and a corresponding eigenvalue respectively. It is seen that the Hurwitz-Nelkin spectrum derived under the assumption of flux separability corresponds to the component having the largest diffusion length, which is reached asymptotically in the region far from the source or the boundary. In the case of a noncapturing medium the eigenvalue problem determining diffusion lengths has been solved rigorously, and for weak absorbers a perturbation method has been developed. It is pointed out that the spectrum in a reactor is constituted by superposing the Hurwitz-Nelkin spectrum upon the others having smaller diffusion lengths, the latter being the contribution from the source distributed continuously near the point considered.