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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.
Robert E. Rothe, D. C. Hunt
Nuclear Science and Engineering | Volume 54 | Number 3 | July 1974 | Pages 360-366
Technical Note | doi.org/10.13182/NSE74-A23427
Articles are hosted by Taylor and Francis Online.
Thirteen previously unpublished critical measurements on enriched (93.16 wt% 235U) uranium metal spheres, which are radially but not axially centered in cylinders of enriched (93.16 wt% 235U) uranium solution, are presented and compared with the results of Monte Carlo calculations. The average reproduction factor calculated for experimentally critical systems was k = 0.989, and this bias showed no systematic variation with the amount the sphere was displaced from center. The sphere size was increased, keeping other parameters constant, until criticality was calculated, at which point the average sphere radius and mass were 2.8 and 8.8%, respectively, greater than the experimental cases. For a given solution cylinder, the minimum critical metal sphere mass occurs when the sphere is centered in the solution. The increase in this critical mass with position along the cylinder axis is also presented parametric in two tank diameters and five solution concentrations. For like asymmetries and at the same concentration, a greater change in the critical sphere mass with position is seen for tanks of large diameter than for smaller tanks. If the tank diameter is fixed, the greater change occurs for solution of high uranium concentration.