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NRC to add new items to categorical exclusions list
The Nuclear Regulatory Commission has identified five categories of action to add to its list of categorical exclusions to reduce its documentation work under National Environmental Policy Act (NEPA) procedures.
These revisions are included in the final rule, “Categorical exclusions from environmental review,” which was published in the Federal Register on March 30. The final rule will become effective on April 29.
Joshua J. Jarrell, Marvin L. Adams, Joel M. Risner
Nuclear Technology | Volume 168 | Number 2 | November 2009 | Pages 424-430
Shielding | Special Issue on the 11th International Conference on Radiation Shielding and the 15th Topical Meeting of the Radiation Protection and Shielding Division (Part 2) / Radiation Protection | doi.org/10.13182/NT168-424
Articles are hosted by Taylor and Francis Online.
A widely used numerical method for discretizing the direction variable in the transport equation is the discrete ordinates technique. Here, we test various discrete ordinates quadrature sets on two three-dimensional (3-D) (X-Y-Z) shielding problems: the doglegged void neutron model and the pool critical assembly model. Commonly used quadrature sets, including the standard level symmetric sets and double Gauss-Chebyshev sets, produce significant ray effects associated with material discontinuities in both models. Abu-Shumays designed the quadruple range (QR) sets specifically for these types of problems and showed that they perform well in two-dimensional X-Y geometry. Here, we show that compared to more commonly used quadrature sets, the 3-D QR sets substantially reduce ray effects associated with material discontinuities in 3-D X-Y-Z discrete ordinates calculations.