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

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2*? 9
Generation of Doppler broadened Cross Sections for Pu,
238 U. 2 3 V 2ft0 PU. 2ttl Pu. 2 * 2 Pu. Fe. Cr. Hi. Mn. Mo. Na
for Hi^ier Temperature for use in Accident Analysis
(M.M. Ramanadhan, V. Gopalakrishnan and S. Ganesan)
Doppler broadened cross sections to temperatures
varying from 300 K to 4500 K were generated for various
fissile, fertile and structural materials usinp the preprocessing
code LINEAR-RECENT and SJGMA1 . Self shielded
2
cross sections were obtained by using the program REX2 .
Summarised below are the steps adapted for obtaining
the cross sections for various elements*
1* Using: code * LINEAR 1 , the evaluated cross sections of
the particular elements from the ENDF/B-IV file, were
linearised to high precision (0.1$).
2. The above linearised data was reconstructed to a reasonable
precision by using code 'RECENT 1 .
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3. For materials like J V and J? Pu which had large data
points, the output obtained from the code RECENT was
further thinned using LINEAR code to an acceptable
precision before going to step h. For the other materials
step h was directly followed.
k. Using the code SIGMA1 the above eross sections were Doppler
broadened to 300 K with 0.0 thinning criteria.
For broadening to temperatures higher than 300 K, one
thinned output for 300 K was taken as input and cross sections
were obtained at a number of temperatures. Since the running
time of code SIGMA1 depends on the number of points input to it
this method of going to higher temperatures was adapted. The
preprocessing experience in the case of U-238 is detailed by
• flow chart in Fig.l.
The doppler broadened outputs were input to the program
REX2 for obtaining the self shielded cross sections.