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Conference Spotlight
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
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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!
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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.
L. A. Hageman, J. B. Yasinsky
Nuclear Science and Engineering | Volume 38 | Number 1 | October 1969 | Pages 8-32
Technical Paper | doi.org/10.13182/NSE38-8
Articles are hosted by Taylor and Francis Online.
Alternating-direction implicit (ADI) time-differencing approximations are developed for the two-dimensional neutron group-diffusion equations. These methods are analyzed for accuracy and stability relative to the implicit-difference approach used in the TWIGL program. It is shown that for model problems (bare homogenous reactors with constant material properties) the ADI method is as accurate as the TWIGL method and much faster computationally. However, several numerical comparisons show that the ADI approach is asymptotically unstable for non-model problems unless extremely small time-steps are used. Such comparisons show the ADI methods (considered in this paper) to be inferior to the TWIGL method for realistic reactor-dynamic problems. A variant on the ADI scheme (ADI-B2) is developed and for a class of delayed supercritical problems shown to be potentially superior to all methods considered.
