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 ANS Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
Latest Magazine Issues
May 2026
Jan 2026
2026
Latest Journal Issues
Nuclear Science and Engineering
June 2026
Nuclear Technology
Fusion Science and Technology
Latest News
NRC proposes changes to its rules on nuclear materials
In response to Executive Order 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” the NRC is proposing sweeping changes to its rules governing the use of nuclear materials that are widely used in industry, medicine, and research. The changes would amend NRC regulations for the licensing of nuclear byproduct material, some source material, and some special nuclear material.
As published in the May 18 Federal Register, the NRC is seeking public comment on this proposed rule and draft interim guidance until July 2.
L. C. Leal, G. de Saussure, R. B. Perez
Nuclear Science and Engineering | Volume 109 | Number 1 | September 1991 | Pages 1-17
Technical Paper | doi.org/10.13182/NSE91-A23840
Articles are hosted by Taylor and Francis Online.
A detailed evaluation of the R matrix resonance parameters describing the interaction of neutrons with 235U has been performed up to 500 eV using the most recent high-resolution measurements of the 235U neutron cross sections. The availability of 235U spin-separated neutron cross-section data, in conjunction with the use of the Δ3 statistics of Metha and Dyson, has made possible a detailed study of the statistical distribution of the resonance parameters and their average values. The present R matrix resonance parameters have been converted into equivalent sets of Adler-Adler parameters and multipole momentum space expansion parameters. Extensive validation of this evaluation has been performed by comparing self-shielded fission rates computed with these R matrix parameters with the measurements of Czirr; a test of the ENDF/B unresolved resonance formalism for the calculation of 235U self-shielding factors is also presented.
