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September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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NRC cuts fees by 50 percent for advanced reactor applicants
The Nuclear Regulatory Commission has announced it has amended regulations for the licensing, inspection, special projects, and annual fees it will charge applicants and licensees for fiscal year 2025.
John T. Mihalczo
Nuclear Science and Engineering | Volume 20 | Number 1 | September 1964 | Pages 60-65
Technical Paper | doi.org/10.13182/NSE20-60
Articles are hosted by Taylor and Francis Online.
Prompt-neutron lifetimes have been determined for unreflected and unmoderated critical assemblies of enriched-uranium metal (93.15% U235) in cylindrical geometry. Five solid cylinders ranging in diameter from 7 to 15 in. and three cylindrical annuli having outside diameters as large as 15 in. were assembled to delayed critical and their prompt-neutron decay constants measured by the Rossi-α technique. The prompt-neutron lifetimes were determined from the measured decay constants and effective delayed-neutron fractions obtained by Sn multigroup transport-theory calculations, which predicted the multiplication constants of all assemblies to within 1/2%. For the solid cylinders the lifetime value is 6.25 ± 0.04 nsec, which, within the limits of experimental errors, is independent of the dimensions of the cylinders and agrees with the lifetime of 6.2 ± 0.1 nsec obtained from earlier prompt-neutron decay-constant measurements with a uranium sphere (Godiva I). For the cylindrical annuli the lifetime varied from 7.0 to 8.0 nsec. The increase in the lifetime value over that of the solid cylinders is due to the time required for neutrons to cross the center void.
