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Conference Spotlight
2025 ANS Winter Conference & Expo
November 8–12, 2025
Washington, DC|Washington Hilton
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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.
Tsahi Gozani
Nuclear Science and Engineering | Volume 36 | Number 2 | May 1969 | Pages 143-158
Technical Paper | doi.org/10.13182/NSE69-A19714
Articles are hosted by Taylor and Francis Online.
A detailed experimental study on the kinetics of a 238U sphere is described. The measurements involve the use of nanosecond electronics and silicon solid-state detector with two fission conversion foils: 235U and 237Np. Thus, some information on the time-energy coupling was obtained. The results show a nonexponential behavior over all time ranges. At longer times, the space and time coupling was small. At early times, the coupling between energy space and time was strong. The early time behavior of the high-energy neutrons (above 237Np threshold) appears to be exponential. The decay constant, however, is a function of position. It is shown that this exponential behavior is a result of a “pseudo-trapping” of neutrons between the fast fission threshold in 237Np and the large step in the inelastic scattering cross section of 238U.
