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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. Z. Müller
Nuclear Science and Engineering | Volume 109 | Number 2 | October 1991 | Pages 200-214
Technical Note | doi.org/10.13182/NSE91-A28518
Articles are hosted by Taylor and Francis Online.
A one-dimensional method based on a combination of the “nodal equivalence theory” and response matrix homogenization methods was previously described for determining environment-insensitive equivalent few-group diffusion theory parameters for homogenized radial reflector nodes of a pressurized water reactor. This reflector model, called the NGET-RM model, yields equivalent nodal parameters that do not account for the two-dimensional structure of the baffle at core corners; this can lead to significant errors in computed two-dimensional core power distributions. A semi-empirical correction procedure is proposed for reducing the two-dimensional effects associated with this particular one-dimensional reflector model. Numerical two-group experiments are performed for a given reflector configuration (and soluble boron concentration) to determine optimal values for the two empirical factors defined by this model. It is shown that the resultant factors are rather insensitive to core configuration or core conditions and that their application yields improved two-group NGET-RM reflector parameters with which accurate nodal power distributions can be obtained. The results are also compared with those obtained with another one-dimensional environment-insensitive model that has an extra degree of freedom utilized here to reduce two-dimensional effects. Some practical aspects related to the application of the proposed correction procedure are briefly discussed.