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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.
E. E. Lewis, C. B. Carrico, G. Palmiotti
Nuclear Science and Engineering | Volume 122 | Number 2 | February 1996 | Pages 194-203
Technical Paper | doi.org/10.13182/NSE96-1
Articles are hosted by Taylor and Francis Online.
The variational nodal formulation of the neutron transport equation is generalized to provide spherical harmonics approximations of arbitrary odd order. The even angular parity trial functions within the nodes are complemented by new odd angular parity trial functions at the node interfaces. These are derived from the spherical harmonic continuity conditions presented in the classical work of Rumyantsev. The Yn±n terms are absent for all odd n in the resulting odd-parity trial function sets. This result is shown to be equivalent to requiring the variational nodal matrix that couples even- and odd-parity angular trial functions to be of full rank and yields vacuum and reflected boundary conditions as well as nodal interface conditions within the framework of the variational formulation. Nodal P1, P3, and P5 approximations are implemented in the Argonne National Laboratory code VARIANT, utilizing the existing spatial trial functions in x-y geometry. The accuracy of the approximations is demonstrated on model fixed source and few-group eigenvalue problems. The new interface trial functions have no effect on P1 approximations and yield P3 results that differ very little from those obtained with existing trial functions, even where the P5 approximation leads to further improvement. More significantly, the new trial functions allow P5 or higher order algorithms to be implemented in a consistent straightforward manner.