SCALE Software Coordinator
Date: Fri Feb 19 15:04:15 2010
In the description of standard composition libraries (M8.2), certain nuclides (MN,NI,FE,and CR) have special weighting functions for generating multigroup cross sections(MN, MNSS, NI-ESIGT, NIINCONEL, NISS, FE-ESIGT, FEINCONEL, FESS, CR-ESIGT, CR-INCONEL, CRSS). The weighting function used to generate multigroup cross sections is usually an assumed energy spectrum such as Chi(fission),1/E(intermediate),Maxwellian (thermal).
What is meant by the following explanation on M8.2.1?
"One special weighting function corresponds to 1/E ót(E), where ót(E) is the total cross section of stainless steel 304. In the other special weighting, ót(E) is the cross section for the referenced nuclide."
When is it appropriate to use special weighted nuclides (SS304 or INCONEL) instead of standard nuclides (SS304S or INCONELS)?
Peter Vescovi
SCALE Software Coordinator
Dear Pete,
The special weightings are appropriate to use for relatively thick zones of the material, especially if using a broad group library. They are also more important for shielding calculations involving these materials than for criticality problems. Note that these weightings have not been generated since the ENDF version 5 libraries 20 years ago. If they are requested in the input but are not available in the chosen library, the default weighted versions are automatically substituted.
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