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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.
J. J. Rush, G. J. Safford, T. I. Taylor, W. W. Havens, Jr.
Nuclear Science and Engineering | Volume 14 | Number 4 | December 1962 | Pages 339-345
Technical Paper | doi.org/10.13182/NSE62-A26240
Articles are hosted by Taylor and Francis Online.
Recent neutron cross-section measurements have shown that certain ammonium salts and methyl substituted compounds may be useful as moderators for cold neutron sources. In the present experiments slow-neutron total cross sections for polycrystalline NH4PF6, (NH4)2S2O8, and (NH4)2CrO4 have been measured at 80°K and 296°K as a function of neutron wavelength. In addition cross sections have been measured at 23°C for NH4SO3F and CH3C≡CCH3. Cross sections vs. temperature for NH4PF6 and (NH4)2S2O8 were also obtained at λn = 8 A (0.0015 ev) from 80°K to room temperature. The long-wavelength slopes in b/A of the scattering cross sections per hydrogen atom at 23°C are: NH4PF6, 12.7; (NH4)2S2O8, 9.6; NH4SO3F, 10.0; (NH4)2CrO4, 5.5; CH3C≡CCH3, 12.4. The slope for NH4PF6 approaches that for free NH3 gas indicating a rotational barrier of ∼0.2 kcal/mole for the ammonium ion. The high slope for CH3C≡CCH3 indicates a low barrier to rotation of the methyl groups in this compound. The lower slopes for (NH4)2S2O8 and NH4SO3F show that the ammonium ions in these compounds have higher barriers of the order of O.7 to 1 kcal/mole. Slopes measured at 80°K are: NH4PF6, 2.5 b/A-H; (NH4)2S2O8, 1.0 b/A-H; (NH4)2CrO4, 0.0 b/A-H. In addition the cross section vs. temperature curve for NH4PF6 indicates no abrupt change in rotational barrier down to 80°K. These low-temperature results show the presence of significant rotational freedom in NH4PF6 even at 80°K. The presence of rotational states at low temperature for exchange of energy with neutrons, together with the comparatively low absorption cross sections, make ammonium salts such as NH4PF6 (N15 enriched) and methyl substituted compounds like CH3C≡CCH3 of interest as moderators for cold neutron sources.
