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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.
J. E. Morel, K. D. Lathrop
Nuclear Science and Engineering | Volume 147 | Number 2 | June 2004 | Pages 158-166
Technical Paper | doi.org/10.13182/NSE04-A2425
Articles are hosted by Taylor and Francis Online.
The integral transport equation clearly indicates that the angular flux in a void is constant along each characteristic. Yet, simple arguments can be used to demonstrate that there exist angular flux solutions in voids that have a delta-function angular dependence and a nonconstant spatial dependence. Such solutions can appear to be nonconstant along a characteristic. Using a simple example problem, we demonstrate that such solutions represent the limit of a continuous sequence of nonsingular solutions, each of which is constant along every characteristic. We also show that care must be taken in applying the integral transport equation to singular problems of this type because erroneous solutions are easily obtained. Two reliable approaches for obtaining proper solutions are presented. We also show that the differential form of the transport equation in one-dimensional spherical geometry requires less care than the integral form of the transport equation for problems of this type. Finally, we discuss the applicability of the Sn method to problems in curvilinear geometries with singular solutions of this type.