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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.
Mohamed Ouisloumen, Abderrafi M. Ougouag, Shadi Z. Ghrayeb
Nuclear Science and Engineering | Volume 179 | Number 1 | January 2015 | Pages 59-84
Technical Paper | doi.org/10.13182/NSE13-99
Articles are hosted by Taylor and Francis Online.
The resonance scattering transfer cross section has been reformulated to account for anisotropic scattering in the center of mass of the neutron-nucleus system. The main innovation over previous implementations is the relaxation of the ubiquitous assumption of isotropic scattering in the center of mass and the actual effective use of scattering angle distributions from evaluated nuclear data files in the computation of the angular moments of the resonant scattering kernels. The formulas for the high-order anisotropic moments in the laboratory system are also derived. A multigroup numerical formulation is derived and implemented into a module incorporated within the NJOY nuclear data processing code. An ultrafine-energy-mesh cross-section library was generated using these new theoretical models and then was used for fuel assembly calculations with the PARAGON lattice physics code. The results obtained indicate that this new model makes a significant difference to predictions of reactivity, multigroup fluxes, and isotopic inventory during depletion.