SCALE Software Coordinator
This topic has been migrated from the SCALE 5 ORIGEN notebook.
Date: Wed Feb 24 20:21:04 2010
I am new to using OrigenArp and have previously used Origen 2.1 for calculations of spent fuel and cladding inventories. I have run some test cases for Magnox, AGR and PWR reactors to compare the results from the 2 programs. We have a list of 112 radionuclides that we are interested in. Most of the radionuclides are comparable (within a factor of 2), but some are very different and I am wondering if this is correct, or if I am doing something different in the new OrigenArp. For each case I have used the same total burnup, the same power basis, total irradiation time, and similar timesteps.
I attach an Excel file containing the results of the comparison, where they are greater than a factor of 2 different. Please could you help in identifying the reasons for the differences.
Jayne Povall
SCALE Software Coordinator
Dear Jayne
This is a complicated question. First of all, when you did the calculations with ORIGEN2.1, what libraries did you use? The library set available with ORIGEN2.1 is fairly limited particularly for non-LWR designs. Also, this version of the code is no longer supported and the libraries have not been updated in many years. Some differences are likely a result cross sections being out of date or not being applicable to the reactor. Some specific examples -- the Se-79 half life is incorrect in ORIGEN2.1 because newer measurements resulted in a large correction to the value. Some Pu isotopes, like Pu-236, are likely a result of missing capture cross section data for Pu-243. Isotopic differences in Am, Cm, Cf may be due to fact that the concentrations are very sensitive to the cross section values. Is there a cross section library for AGR with ORIGEN2.1? Substituting approximate libraries can sometimes lead to large differences.
Many of these differences need to be looked at on a case-by-case basis since the reasons for differences are not always the same. The causes are generally nuclear decay data, completeness of the chains, and cross section values. Some differences, particularly for several metastable activation products, may be a result of deficiencies in the ORIGEN-ARP cross sections. A data processing problem resulted in the base library for ORIGEN being updated (see description in http://www.ornl.gov/sci/scale/origen_update.htm ) While this corrects the newer libraries (like W17x17), some older libraries like AGR and MAGNOX still contain the older data since they have not been remade.
Don't hesitate to contact me if you have any questions or would like to pursue specific discrepancies further.
Regards
Ian Gauld