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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.
R. L. French, L. G. Mooney
Nuclear Science and Engineering | Volume 47 | Number 3 | March 1972 | Pages 375-380
Technical Note | doi.org/10.13182/NSE72-A22425
Articles are hosted by Taylor and Francis Online.
The “last-collision” method for computing the air-ground interface effect on scattered neutron intensity is extended to give the effect on the intensity within individual polar angle groups at a detector near the ground. The method yields angle-dependent perturbation factors which can be used to adjust infinite-air angle distributions to account for the presence of an air-ground interface, or to adjust angle distributions from one detector height to another. To determine the factors, a uniform scattering distribution in the air about the detector is assumed, and the fractional contribution from each last-collision center in the air is calculated. In addition, the fraction scattered directly to the detector from the ground surface is calculated using a simplified albedo model. An evaluation of the angle-dependent last-collision model indicated that the results of discrete ordinate calculations for infinite air could be modified to give relative polar angle distributions of the scattered neutron dose near the air-ground interface within 10 to 20% of those calculated directly for the air-over-ground case by the discrete ordinate method.