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
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
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
Oct 2025
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
November 2025
Nuclear Technology
Fusion Science and Technology
Latest News
Japan gets new U for enrichment as global power and fuel plans grow
President Trump is in Japan today, with a visit with new Prime Minister Sanae Takaichi on the agenda. Takaichi, who took office just last week as Japan’s first female prime minister, has already spoken in favor of nuclear energy and of accelerating the restart of Japan’s long-shuttered power reactors, as Reuters and others have reported. Much of the uranium to power those reactors will be enriched at Japan’s lone enrichment facility—part of Japan Nuclear Fuel Ltd.’s Rokkasho fuel complex—which accepted its first delivery of fresh uranium hexafluoride (UF₆) in 11 years earlier this month.
C. B. Mills, G. I. Bell
Nuclear Science and Engineering | Volume 12 | Number 4 | April 1962 | Pages 469-473
Technical Paper | doi.org/10.13182/NSE62-A26093
Articles are hosted by Taylor and Francis Online.
In this paper we present calculated critical masses of homogeneous water-moderated assemblies containing low enrichment uranium. The calculations were made using the multigroup DSN code with eighteen energy groups. Effective absorption cross sections for U238 were computed with the “infinite mass” and “narrow resonance” approximations. The calculations have been compared with various experiments and rather good agreement was found. The results are presented as a parametric survey for U235/U atom ratios from 0.014 to 0.300 and for all H/U235 ratios for which criticality is possible. The decrease in critical radius with an infinite water reflector is also shown. We find that a bare homogeneous system with U235/U < 0.010 cannot be made critical at any H/U235 ratio.
