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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.
Takashi Nakamura, Toshiso Kosako
Nuclear Science and Engineering | Volume 77 | Number 2 | February 1981 | Pages 168-181
Technical Paper | doi.org/10.13182/NSE81-A21351
Articles are hosted by Taylor and Francis Online.
The skyshine of monoenergetic neutrons directed upward from sources both as a vertically collimated beam and as a point isotropic cone fixed on the ground has been calculated systematically by a Monte Carlo method for distances up to ∼2 km from the source. The energy of the neutrons ranged from 14 MeV to thermal. The calculated skyshine spectra approach an approximate equilibrium having an approximate 1/E dependence in the keV region beyond about a few hundred metres from the source. The total neutron flux Φ(r) and dose D(r) at a distance r from a source are well represented by a simple formula, and D(r) = QDexp(-r/λD)/r, and the constants , and λD are only dependent on the source-neutron energy. In respect to the dependence of , and QD on the upward aperture, θs, of the cone source and λD change very little with θs, but and QD increase with θs, when θs is larger than 30 deg. This simple formula was applied to evaluate the experimental results of skyshine neutron doses from a fast-neutron source-reactor facility and showed nice agreement.
