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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.
M. Srinivasan, K. Subba Rao, S. B. Garg, G. V. Acharya
Nuclear Science and Engineering | Volume 102 | Number 3 | July 1989 | Pages 295-309
Technical Paper | doi.org/10.13182/NSE89-A27479
Articles are hosted by Taylor and Francis Online.
A number of interesting systematics and correlations have been deduced by analyzing the criticality data of special actinide nuclides using concepts embodied in the Trombay criticality formula (TCF). The k∞ of fast metal actinide nuclides gives a remarkable linear correlation with the fissility parameter Z2/A. The neutron leakage probability of all fast metal cores characterized using a constant parameter σstd enables computation of the critical mass value of any unknown fissile nuclide knowing only its Z2/A value. Since the neutron leakage probability from dilute fissile solutions is primarily governed by the scattering/slowing down properties of the hydrogen present in water, critical masses and subcritical limits can be predicted for any water-reflected system at any specified hydrogen-to-actinide atomic ratio knowing only the k∞ value of the given fissile solution. In the case of fast fissible actinide systems, the neutron leakage probability can be characterized by a single parameter σstd, but having a slightly different value from that of fast fissile systems. Due to their fission thresholds, however, attempts to deduce any systematics in their k∞ values have not been very successful. The importance of compiling not only critical radius/mass data but also k∞, the critical surface mass density , the degree of reflection parameter Y, etc., has been clarified while preparing criticality data tabulations for ready reference. These quantities can be used along with the TCF to compute core dimensions and fissile inventories required to yield any specified safe subcritical keff value.
