I am running a very simple fixed source simulation:
- Geometry: spherical shell (r_min = 800cm, r_max = 1050cm)
- Material: Li17Pb83
- Source: isotropic at 14.1MeV
- settings.photon_transport = True
I am trying to compute the radial distribution of the neutron flux and power deposition. To do so I wrote the following tallies
radial_mesh = openmc.SphericalMesh(name='Radial Mesh', r_grid=r_coords)
mesh_filter = openmc.MeshFilter(radial_mesh)
particle_filter = openmc.ParticleFilter(['neutron', 'photon'])
radial_tally = openmc.Tally(name='Radial')
radial_tally.filters = [mesh_filter, particle_filter]
radial_tally.scores = ['flux', 'heating']
tallies.append(radial_tally)
The odd behaviour that I am noticing is that the resulting flux distribution changes if I don’t score the heating, but only the flux, i.e. radial_tally.scores = ['flux']. The changes are not minimal but clearly visible when plotting the radial distribution.
Interestingly, this discrepancy doesn’t appear if I filter over the entire Cell instead of using the mesh_filter.
Intuition leads me to think that the cleanest and correct result is obtained separing the scores in different tallies. However, only if I include the heating score then the average flux (weighted by the volumes) obtained from the radial distribution matches the one from filtering over the entire Cell.
Thank you in advance!