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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.
A. Dubi, T. Elperin, Donald J. Dudziak
Nuclear Science and Engineering | Volume 80 | Number 1 | January 1982 | Pages 139-161
Technical Paper | doi.org/10.13182/NSE82-A21411
Articles are hosted by Taylor and Francis Online.
Through a direct statistical approach, analytic expressions are derived for the second moment, the variance ratio, and benefit functions of a model for n-surface geometric splitting. The model is general in that it can be applied to many geometric and material conditions, energy dependence, and biasing methods besides splitting. The model applies to any detector, provided that the detector region is separated from the source region. The model has the following limitations: (a) every source particle reaching the detector must cross all splitting surfaces, (b) particles are allowed to split only once on each surface, (c) weight-dependent biasing schemes are not included, and (d) reactions that bifurcate the particle are excluded. The derived expressions depend linearly on n unknown constants that are bulk properties of the medium in a given problem. These constants may be estimated approximately from one small sample run invoking the point-surface approximation or from (n + 1) consecutive small sample runs. Numerical examples are given in verification of the theory, and the possibility of using the expressions in an in-code optimization or self-optimizing code is discussed.