Energy deposition for coupled neutron-photon calculations

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1

Hi all,

I tried to reproduce the simulation of this notebook, attached in the Pull Request #1449, and I’ve got different values for the photon heating (the values for the neutron heating are the same, but the ‘heating’ tally gives 180 MeV/fission and ‘heating-local’ gives 198 MeV/fission when used them to the determine the average amount of fission energy deposited per fission).

Also, I simulated an infinite medium of U235 with a monoenergetic photon source of 5 MeV, mentioned as an older issue in the Pull Requests #1453 and #1462, and I’ve got different values for the heating tally with TTB (6.28e5 eV) and LED (6.14e5 eV), which are not only different from each other but also different from the energy of the source.

I’m using the develop version of the code and the official nuclear data libraries (endfb71_hdf5). So, I’d like to know if the Pull Request #1462 is the reason why I get different results than the mentioned notebook, and how I can get the total energy deposition in an infinite medium.

Thanks in advance,

Norbert

2

Hi Norbert,

If you want the total energy deposition, you should either 1) not use a particle filter or, 2) if you use a particle filter, make sure you list neutron, photon, electron, and positron. One of the changes resulting from #1462 is that the code is now able to differentiate between the energy deposited from photon collisions and electron/positron collisions. Thus, using a particle filter with only neutrons and photons won’t actually give you all the energy deposited (most of the energy deposited on the photon side is really from electrons).

Best,
Paul

3

Thanks Paul, it works perfectly!

Norbert