# Normalization of Fission reaction rates **URL:** \ **Category:** User Support\ **Created:** [March 5, 2022, 3:23pm UTC](https://openmc.discourse.group/t/normalization-of-fission-reaction-rates/1763 "2022-03-05T15:23:18Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![imtiaj\_hossain](https://avatars.discourse-cdn.com/v4/letter/i/90db22/32.png) [@imtiaj\_hossain](https://openmc.discourse.group/u/imtiaj_hossain)\ **Post date:** [March 5, 2022, 3:23pm UTC](https://openmc.discourse.group/t/normalization-of-fission-reaction-rates/1763/1 "2022-03-05T15:23:18Z")
Hi , i’m trying to find cell average fission reaction rates using DistribcellFilter which gives the value in reactions/source . By multiplying it with the normalization factor (P_nu)/(Q_k) which has the unit source/sec i’m able to get the reaction rates value in fission reactions/s.But here, P= power in J/s nu=nu-fission/fission (neutrons/fission) Q=200MeV (3.2e-11J/fission) k=eigenvalue obtained by running the simulation (neutrons/source) so, by multiplying it with fission score i get the value in fission/sec. but if R is the normalized fission reaction rate & f is the scored fission rate then R=f\*(P_nu)/(Q_f_k) =\> R= (P_nu)/(Q\*k) [f got eliminated] So, To find the fission rates i’m not using the fission reaction rate score at all. Is this correct? But the value i obtained doesn’t match with the existing solution? Can anyone clear my doubt? ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [March 7, 2022, 5:44pm UTC](https://openmc.discourse.group/t/normalization-of-fission-reaction-rates/1763/2 "2022-03-07T17:44:16Z")
I generally don’t recommend using (P_ν)/(Q_k) as a normalization factor. Please see the user’s guide section on [tally normalization](https://docs.openmc.org/en/latest/usersguide/tallies.html#normalization-of-tally-results) that describes a better approach based on the `heating` or `heating-local` score. ---
**Author:** ![imtiaj\_hossain](https://avatars.discourse-cdn.com/v4/letter/i/90db22/32.png) [@imtiaj\_hossain](https://openmc.discourse.group/u/imtiaj_hossain)\ **Post date:** [March 7, 2022, 5:48pm UTC](https://openmc.discourse.group/t/normalization-of-fission-reaction-rates/1763/3 "2022-03-07T17:48:10Z")
@paulromano thank you for your reply. If the power produced by core is unknown (in case it’s not in operating state) then what value should be used for P here? ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [March 7, 2022, 8:04pm UTC](https://openmc.discourse.group/t/normalization-of-fission-reaction-rates/1763/4 "2022-03-07T20:04:05Z")
If the power produced by the core is unknown, then it’s also not physically possible to know what the absolute fission reaction rates are either. ---
**Author:** ![imtiaj\_hossain](https://avatars.discourse-cdn.com/v4/letter/i/90db22/32.png) [@imtiaj\_hossain](https://openmc.discourse.group/u/imtiaj_hossain)\ **Post date:** [March 7, 2022, 8:16pm UTC](https://openmc.discourse.group/t/normalization-of-fission-reaction-rates/1763/5 "2022-03-07T20:16:13Z")
@paulromano i got it. Thank you. ---
**Author:** ![imtiaj\_hossain](https://avatars.discourse-cdn.com/v4/letter/i/90db22/32.png) [@imtiaj\_hossain](https://openmc.discourse.group/u/imtiaj_hossain)\ **Post date:** [March 9, 2022, 6:53am UTC](https://openmc.discourse.group/t/normalization-of-fission-reaction-rates/1763/6 "2022-03-09T06:53:06Z")
hi @paulromano can you tell me if there is a way to get the isometric plot of the flux density plot mentioned is this example? [https://nbviewer.org/github/openmc-dev/openmc-notebooks/blob/main/post-processing.ipynb](https://nbviewer.org/github/openmc-dev/openmc-notebooks/blob/main/post-processing.ipynb) Best Regards Imtiaj ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [March 9, 2022, 1:31pm UTC](https://openmc.discourse.group/t/normalization-of-fission-reaction-rates/1763/7 "2022-03-09T13:31:01Z")
@imtiaj_hossain I’m not aware of any easy way to do that. @pshriwise has been working on some capabilities to take mesh tallies and export them to VTK files, which could them be visualized in 3D using ParaView or a similar program, so that might be an option in the future.