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.
Richard Sanchez, Norman J. McCormick
Nuclear Science and Engineering | Volume 147 | Number 3 | July 2004 | Pages 249-274
Technical Paper | doi.org/10.13182/NSE04-A2432
Articles are hosted by Taylor and Francis Online.
The limitations of asymptotic methods for numerically solving highly forward peaked scattering (HFPS) problems are reviewed before resorting to a discrete ordinates solution for such problems based on biased angular quadrature formulas to increase the precision of the angular representation and on source evaluation from cell-averaged angular fluxes to reduce memory requirements. Also, a twice-collided source is introduced to avoid numerical representation of singularities in the solution. As an example the propagation and spreading of a collimated particle beam in an HFPS medium has been calculated with a discrete ordinates diamond-differenced numerical solution of the transport equation in two-dimensional curvilinear cylindrical coordinates. The calculation was carried out for a strongly forward peaked Henyey-Greenstein scattering law for which Fokker-Planck asymptotic models are not valid. The results show promise for numerically calculated reference solutions based on accurate spatial representations for checking the accuracy of standard asymptotic models for these types of problems.