Specification of a generally useful multigroup structure for neutron transport

Abstract

This report represents the work of a committee appointed and directed by the Codes and Formats Subcommittee of the Cross Section Evaluation Working Group and is parallel to that already completed for the thermal range. It is an attempt to suggest reasonable energy bouris, weighting function and output format for a "standardized" multigroup library in the fast energy range (>1 eV) to be prepared for general distribution. Although the emphasis is clearly directed toward the LMFBR program, the large number of groups (-250) has made it possible to include the majority of CTR, shielding, and weapons requirements with the notion that a problem dependent group structure can be obtained conveniently at run time by a simple collapsing procedure.The new structure is compatible with past design experience and incorporates detailed representation for specific cross section features known to be important in a wide range of nuclear design applications.

Integrated system for production of neutronics and photonics calculational constants. Volume XVI. Tabular and graphical presentation of 175 neutron group constants derived from the LLL evaluated neutron data library (ENDL)

“…The total mean free path is calculated from pN"a T where p = density in g/cm 3 ; ** N" = 0.6022169, <r T = total cross section in barns (10~2 4 where /%,, is the average elastic-scattering cosine in the laboratory system. In deriving Jim,, our starting point was the output from the CLYDE code.…”

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“…48B* c 3 3l~* z 9.240* 0 9.285* 0 7.052' 0 7 0!B 0 3 394-2 9 539-2! 2.267-2 1 665-1 .339- 4 9.260* 0 9.305* 0 7.036+ 0 7.003 0 3.392-2 9.532-2i 2.271-2 1 973-1 .406- 4 9.2B4* 0 9.329* 0 7.018* 0 6 984 0 3 389-2 9.523-2 2 275-2 2.097-1.511- 4 9.31! * 0 9.357* 0 6 998 + 0 6 964 0 3.3B6-2 9.514-2 2.279-2 2237-1 .601- 4 9.337' 0 9.393* 0 6.979* 0 6.945 0 3 383-2 9.505-2 2.283-2 2.369-1.694- 4 9.364.…”

“…2.267-2 1 665-1 .339- 4 9.260* 0 9.305* 0 7.036+ 0 7.003 0 3.392-2 9.532-2i 2.271-2 1 973-1 .406- 4 9.2B4* 0 9.329* 0 7.018* 0 6 984 0 3 389-2 9.523-2 2 275-2 2.097-1.511- 4 9.31! * 0 9.357* 0 6 998 + 0 6 964 0 3.3B6-2 9.514-2 2.279-2 2237-1 .601- 4 9.337' 0 9.393* 0 6.979* 0 6.945 0 3 383-2 9.505-2 2.283-2 2.369-1.694- 4 9.364. 0 9.409+ 0 6.959* 0 6.925 0 3.379-2 9.497-2 2288-2 2.504-1.789- 4 9.391* 0 9.437* 0 J.939+ 0 6.905 0 3 376-2 9.467-2 2.292-2 2.643-1.887- 4 9.419* 0 9.465+ 0 6.918+ 0 6.BB4 0 3.373-2 9.478-2 2.297-2 2 7B6-1.98B- 4 9.449* 0 9.495* 0 6.896+ 0 6.B63 0 3.369-2 9.468-2 2.302-2 2.933-2.091- 4 9.497.…”