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NRC proposes changes to its rules on nuclear materials
In response to Executive Order 14300, “Ordering the Reform of the Nuclear Regulatory Commission,” the NRC is proposing sweeping changes to its rules governing the use of nuclear materials that are widely used in industry, medicine, and research. The changes would amend NRC regulations for the licensing of nuclear byproduct material, some source material, and some special nuclear material.
As published in the May 18 Federal Register, the NRC is seeking public comment on this proposed rule and draft interim guidance until July 2.
F. H. Fröhner
Nuclear Science and Engineering | Volume 106 | Number 3 | November 1990 | Pages 345-352
Technical Paper | doi.org/10.13182/NSE89-177
Articles are hosted by Taylor and Francis Online.
Recent measurements define the prompt fission neutron spectrum of 252Cf from 25 keV to 20 MeV with sufficient accuracy to show that the standard representation by a Maxwell spectrum with the temperature parameter TM = 1.42 MeV is not adequate. The next simplest macroscopic representation, a Watt spectrum with the two parameters Tw = 1.18 MeV and Ew = 0.36 MeV, fits the recent data surprisingly well, at least as well as the best currently available microscopic models of fission neutron emission. The resulting chi-square does not indicate any need for a more sophisticated description, nor is the fit improved by refinements such as superposition of two Watt distributions (for a representative fragment pair), or relativistic corrections.
