# Openmc 13.2 and FISPAC-II resulted in very different isotopes

**URL:** <https://openmc.discourse.group/t/openmc-13-2-and-fispac-ii-resulted-in-very-different-isotopes/2874>\
**Category:** User Support\
**Created:** [March 31, 2023, 3:41am UTC](https://openmc.discourse.group/t/openmc-13-2-and-fispac-ii-resulted-in-very-different-isotopes/2874 "2023-03-31T03:41:11Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Daniel](https://avatars.discourse-cdn.com/v4/letter/d/3ec8ea/32.png) [@Daniel](https://openmc.discourse.group/u/Daniel)\
**Post date:** [March 31, 2023, 3:41am UTC](https://openmc.discourse.group/t/openmc-13-2-and-fispac-ii-resulted-in-very-different-isotopes/2874/1 "2023-03-31T03:41:11Z")

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I am performing a benchmark depletion analysis comparison (for Fixed neutron Source Transmutation Calculations) between FISPAC-II and openmc 13.2. I have noticed that the two codes resulted in very different isotopes. FISPAC-II report activity for the following isotopes:  
[simulate\_NbVMoCr\_deple.py](https://openmc.discourse.group/uploads/short-url/z89UVSHDKgb5j2S6Pl6gpIkrQKX.py) (2.9 KB)

Nb 91, Nb 91m, Nb 92m, Nb 93m, Nb 94, Nb 95, Mo 99, Mo 93, Tc 99m, Y90, H3, Sc 48, V49, Cr 51

Where as Openmc report activity for the following isotopes:

Nb94, Nb95, Mo99, Mo100, Tc99, Y90, Y91, H3, Zr95, Zr93, Ru103, Sr89, Rb86, Sr90, Kr85,V50,Rb87, Zr96,K40

I then used different depletion chain files found at ([Depletion Chains | OpenMC](https://openmc.org/depletion-chains/)), for example 0.12 endfb71\_pwr.xml chains which made no difference.

Any insight on what might be going on will be much appreciated.

Thank you.