Dear OpenMC users,
I am using OpenMC to calculate the shielding needed for a neutron source. I have a couple of quick questions that I would appreciate your help with:
1- I have different materials such as water, concrete, and HDPE in my simulation. I also want to calculate the dose from secondary photons. To do this, I have added “settings.photon_transport = True” to my code and defined a tally as shown below to post-process and get the dose from photons. I was wondering, will OpenMC automatically consider the interaction of neutrons with all the different materials and include all neutron-induced photons in the simulation, or do I need to add anything else?
Dose tally for photon
energy_bins_p, dose_coeffs_p = openmc.data.dose_coefficients(particle=“photon”, geometry=“AP”)
energy_function_filter_p = openmc.EnergyFunctionFilter(energy_bins_p, dose_coeffs_p)
energy_function_filter_p.interpolation = “cubic”
particle_filter_p = openmc.ParticleFilter(‘photon’)
dose_tally_p = openmc.Tally(name=“photon_dose_on_mesh”)
dose_tally_p.filters = [mesh_filter, particle_filter_p, energy_function_filter_p]
dose_tally_p.scores = [“flux”]
2- I am using the code below to calculate the dose. If I am not mistaken, the dose coefficients are in the unit of pSv·cm². When using a phantom (a cylinder with human body dimensions) to convert it to pSv, should I divide by the phantom volume as shown in this example (neutronics-workshop/tasks/task_09_CSG_instantaneous_dose_tallies/3_cell_dose_from_neutron.py at fc62845f081dbb125947f0700526054fe67f3e1c · fusion-energy/neutronics-workshop · GitHub), or should it be normalized by the phantom surface area? Similarly, when I calculate the dose on mesh elements, should I normalize the values by the volume of the mesh elements?
phantom_tally_n = openmc.Tally(name=f"phantom_neutron_dose")
phantom_tally_n.filters = [openmc.CellFilter(phantom_cell), particle_filter_n, energy_function_filter_n]
phantom_tally_n.scores = [“flux”]
phantom_tally_n = sp.get_tally(name=f"phantom_neutron_dose")
phantom_dose_n = phantom_tally_n.mean.flatten()[0]
phantom_volume = np.pi * 10.782 * 10.782 * 169.75
phantom_dose_n_rem_year = phantom_dose_n * (neutron_flux / phantom_volume) * 1e-9 * 60 * 60 * 24 * 364 * 0.1 // Convert to rem/year
3- I am defining dry air as below. If I want to add humidity (e.g., 80%), should I simply add the “H” element to the composition, or is there another method or library data I can use?
mat_air = openmc.Material(name=“Air”)
mat_air.add_element(“N”, 0.784431)
mat_air.add_element(“O”, 0.210748)
mat_air.add_element(“Ar”, 0.0046)
mat_air.set_density(“g/cc”, 0.001205)
Thanks for your help!