INDC(IND)-35G - IAEA Nuclear Data Services

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grouping such that the multigroup constants exactly reprsssnt
the evaluated data, Tnus improvements in processing has
resulted in the routines for direct numerical Doppler Broadening
oT cross sections in resonance region without using the J*
formalism,
The program REX2 calculates the self shielded cross
sections and the self shielding factors for a set of input
dilutions from the exactly Doppler broadened point cross
sections made available at a specified temperature by running
the preprocessing code SIGMAt. If the cross section data comes
a
from the original ENDP library at OK, then, SIGMA1 requires the
data to be preprocessed by the LINEAR -RECENT code system.
The program REX2 replaces the older routines of
RANBRA based on approximate J* method of Hwang in the resolved
resonance region.
Hie temperature (T) and dilution( (J" ) dependent
cross section known as the shielded cross section of any material
for • group g is computed using Bondarenko definition as
/
S C £
(Tg(BfT) is the cross section at energy point E and
temperature T for a process x; x it t, C, f or >,
S(S) is
l:
the slowly varying weighting function
for flux weighting used for It other than t
and H» , 2 for current weighting used when % is t.
N