SCALE Software Coordinator
This topic has been migrated from the SCALE 5 ORIGEN notebook.
Date: Tue Oct 28 11:28:57 2008
I know that OrigenARP is used mainly for burn-up calculations but I plan on using using OrigenARP not for burn-up calculations, but to decay and generate a gamma source term (mainly from actinides) to be used as an input for MCNP. Presently on the decay tab, I am turning off the bremsstrahlung but was wondering if there is there anything special I should be doing regarding the [alpha,n], [alpah,n] cutoff, or alpha groups to use OrigenARP in the manner I would like in order decay and generate an accurate source term. If I am way off base or have any suggestions with how I am intending to use OrigenARP, please let know.
Thanks in Advance!
Jerry George
SCALE Software Coordinator
Dear Jerry
These are good questions. The default cutoff values are sufficient for typical LEU spent fuel analyses, but for your application it is worth verifying. The values are used to eliminate low contributing sources and target nuclides. In addition, since the removal criterion are calculated for a given time (corresponding to step MSTAR), if the compositions change dramatically over the decay interval then the cutoff may not be suitable. To confirm this, simply reduce the cutoff to a much smaller value (orders of magnitude smaller) and confirm this does not have a significant impact on the resulting (alpha,n) source. The number of alpha energy groups used in the calculation is a parameter taken directly from the SOURCES code. The default in SOURCES is 2000, but we have found that results are fairly insensitive when using fewer groups. Simply increase NAG to verify that the default is adequate for your application. Note that these options are briefly discussed in the ORIGEN manual Section F7.2.8.2.
Feel free to contact me if you want to discuss or need more information.
Regards
Ian Gauld