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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.
C. R. Richey
Nuclear Science and Engineering | Volume 31 | Number 1 | January 1968 | Pages 40-48
Technical Paper | doi.org/10.13182/NSE68-A18006
Articles are hosted by Taylor and Francis Online.
Experimental data to establish criticality control specifications for enriched uranium rods undergoing dissolution are extremely limited. A principal difficulty in treating the problem theoretically is that the resonance absorbing 238U is admixed in the aqueous solution in which the rods are immersed. The “narrow resonance” and “infinite mass” approximations are applied; and from this application, expressions are developed for treating resonance capture by an absorbing lump embedded in a moderator admixed with the absorber. The computed change in the critical buckling of a heterogeneous array on replacing the water moderator by a uranyl nitrate solution is in good agreement with experiment. Results from survey calculations for 3 and 5 wt% 238U rods latticed in uranium-water mixtures are given. It was concluded that for enrichments up to 5 wt% 235 U, dissolver vessels designed geometrically safe for water-moderated arrays of uranium rods will remain safe during the dissolution process.
