Abstract
With current and ongoing interest in high temperature gas reactors (HTGRs), the U.S. Nuclear Regulatory
Commission (NRC) anticipates the need for nuclear data libraries appropriate for use in applications for
modeling, assessing, and analyzing HTGR reactor physics and operating behavior. The objective of this
work was to develop a broad-group library suitable for production analyses with SCALE for HTGR
applications. Several interim libraries were generated from SCALE fine-group 238- and 999-group
libraries, and the final broad-group library was created from Evaluated Nuclear Data File/B Version
ENDF/B-VII Release 0 cross-section evaluations using new ORNL methodologies with AMPX, SCALE,
and other codes. Furthermore, intermediate resonance (IR) methods were applied to the HTGR broadgroup
library, and lambda factors and f-factors were incorporated into the library’s nuclear data files. A
new version of the SCALE BONAMI module named BONAMI-IR was developed to process the IR data
in the new library and, thus, eliminate the need for the CENTRM/PMC modules for resonance selfshielding.
This report documents the development of the HTGR broad-group nuclear data library and the
results of test and benchmark calculations using the new library with SCALE. The 81-group library is
shown to model HTGR cases with similar accuracy to the SCALE 238-group library but with
significantly faster computational times due to the reduced number of energy groups and the use of
BONAMI-IR instead of BONAMI/CENTRM/PMC for resonance self-shielding calculations.