Significant Difference b/w dose of Cell Tally and Mesh Voxel Result

User Support
1

i am modeling a shielding problem and my model includes tallies both with cell filter and mesh filter. but the difference of dose is about order of 3. Probably I am missing something while calulating dose using Mesh filter.

My Mesh tallies: Dose_tally_2 = openmc.Tally(name=“dose tally_2”)
Dose_tally_2.filters = [mesh_filter, energy_function_filter_p ,particle_filter]
Dose_tally_2.scores = [“flux”]
Dose_tally_2.estimator = ‘tracklength’
Dose_tally_2.id = 5

My Cell tallies: photon_filter = openmc.ParticleFilter([‘photon’])
dose_tally.filters = [cells_filter, energy_function_filter_p,photon_filter]
dose_tally.scores = [‘flux’]
dose_tally.estimator = ‘tracklength’
dose_tally.id = 6

For final result I am dividing cell-tally by respective volume. The Cell filter results matches with reference values.

3

Hello @Ghotme

I think the default tally unit in OpenMC is not divide by volume as this is also written in the documentation that unit of flux tally is n-cm. Can you please clarify if the flux tally is indeed divided by volume inherently

4

Hello @NrnAktr

How did you calcualate the final flux tally in mesh filter, i.e. did you divide by the individual mesh volume?

6

Thanks @yajat and @Ghotme . I got the error. I was extracting results in wrong way.

@Ghotme However, OpenMC tallies are not already normalized by the region or voxel volume like in other codes.