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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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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.
Robert G. Cockrell, R. B. Perez and G. R. Dalton
Nuclear Science and Engineering | Volume 19 | Number 4 | August 1964 | Pages 423-430
Technical Paper | doi.org/10.13182/NSE64-A18999
Articles are hosted by Taylor and Francis Online.
The one-speed, time-dependent, source-free Boltzmann integro-differential neutron-transport equation is used to study the time dependence of monoenergetic neutrons in a spherical homogeneous medium. By applying the Marshak boundary condition at the outer face instead of the usual vanishing of the scalar flux at some extrapolated boundary, two coupled characteristic equations are derived which relate the time constants and space eigenvalues of the sphere in terms of its geometric radius and the nuclear parameters of the medium. Tables and graphs of the fundamental space eigenvalue and time constant are given for 0.82- and 1.24-MeV neutrons in lead. Numerical values of the time constant as a function of the size of the system are compared for several PN approximations ranging from P1 to P15. The results of fitting experimental data with the characteristic equation of the P7 approximation are given; they compare favorably with published values obtained by others. A method is given for determining the angular moments of a Legendre polynomial expansion of the scattering kernel from pulsed-neutron data.
