SCALE Software Coordinator
This topic has been migrated from the SCALE 5 ORIGEN notebook.
Date: Wed Jul 15 07:39:26 2009
An error in the Cf-250 spontaneous fission neutron source term calculated by ORIGEN-S was identified. The problem affects versions of ORIGEN-S in SCALE 5.0 and later. These versions use neutron source routines from the SOURCES code (RSICC CCC-661). The cause is an incorrect value for the Cf-250 spontaneous fission branching fraction in the SOURCES decay data library used by ORIGEN-S, resulting in a specific Cf-250 spontaneous fission rate about 20 times too large. The branching fraction for Cf-252 in the neutron data library (3.092e-2) is incorrectly also used for Cf-50 (value should be 7.7e-4). The correction can be easily made by modifying the data file
\scale5\data\origen_data\origen.rev00.alphdec.data, by replacing lines
982500 4 , cf250
1.67928e-09 3.09200e-02 3.53000e+00
with
982500 4 , cf250
1.67928e-09 7.70000e-04 3.53000e+00
A new revision of the library will be posted shortly on the SCALE website.
Ian Gauld