Hi all,

I wonder if there is a way to get the fast neutron fluence in the depletion calculation? I learned from forums how to normalize neutron fluence. Although I have some guesses on how to calculate the fast neutron flux, I am not sure of its correctness. So I hope someone can teach me how to get the fluence of fast neutrons knowing the power. I would be very grateful for any advice

Zhiying

You can create a tally for the fast neutron flux (this example doesn’t have a spatial filter but you may want to include one):

```
tally = openmc.Tally()
tally.filters = [
openmc.EnergyFilter([E_low, E_high])
]
tally.scores = ['flux']
...
model.tallies.append(tally)
```

Then, when you run a depletion calculation, each statepoint file (`openmc_simulation_n#.h5`

) will have the result of that tally. You can multiply the tally result (flux) by the depletion timestep length to get a fluence. Also, it is up to you to define what “fast” is, that is, you would need to select `E_low`

and `E_high`

.