Nuclear Science and Engineering -- ANS / Publications / Journals / Nuclear Science and Engineering

About ANS
- ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
About Nuclear
- Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Communities
- Division Spotlight
  Young Members Group
  The Young Members Group works to encourage and enable all young professional members to be actively involved in the efforts and endeavors of the Society at all levels (Professional Divisions, ANS Governance, Local Sections, etc.) as they transition from the role of a student to the role of a professional. It sponsors non-technical workshops and meetings that provide professional development and networking opportunities for young professionals, collaborates with other Divisions and Groups in developing technical and non-technical content for topical and national meetings, encourages its members to participate in the activities of the Groups and Divisions that are closely related to their professional interests as well as in their local sections, introduces young members to the rules and governance structure of the Society, and nominates young professionals for awards and leadership opportunities available to members.
Events
- Meeting Spotlight
  Nuclear and Emerging Technologies for Space (NETS 2025)
  May 4–8, 2025
  Huntsville, AL|Huntsville Marriott and the Space & Rocket Center
Standards
- 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!
Publications
- Latest Magazine Issues
  May 2025
  Jan 2025
  Latest Journal Issues
  Nuclear Science and Engineering
  June 2025
  Nuclear Technology
  June 2025
  Fusion Science and Technology
  May 2025
- Latest News
  U.S. nuclear capacity factors: Stability and energy dominance
  Nuclear generation has inertia. Massive spinning turbines keep electricity flowing during grid disturbances. But nuclear generation also has a kind of inertia that isn’t governed by the laws of motion.
  Starting—and then finishing—a power reactor construction project requires significant upfront effort and money, but once built a reactor can run for decades. Capacity factors of U.S. reactors have remained near 90 percent since the turn of the century, but it took more than a decade of improvements to reach that steady state. The payoff for nuclear investments is long-term and reliable.
Search

In neutron chain systems with material symmetries, various k-eigenvalues of the neutron balance equation beyond the dominant one may be degenerate. Eigenfunctions can be partitioned into several classes according to their invariance properties with respect to the symmetry operations (mirror symmetries and rotations) keeping the material distribution in the system unchanged. Their calculation can be limited to a fraction of the system (sector) provided that innovative boundary conditions matching the symmetry classes are used, and whole-system eigenfunctions can then be unfolded from the solutions obtained over the sector. With power iteration as the method for searching k-eigenvalues, this use of the material symmetries to split the global problem into a variety of smaller-sized problems has several computational advantages: lower computation times and memory requirements, increased dominance ratios, lowered possible degeneracies in each subproblem, and possible parallel (separated) treatment of the subproblems. The implementation is discussed in a companion paper using diffusion and transport theories.