Dear openMC team,
This question does not concern any issue in the code but is more linked with my curiosity.
I am trying to understand about the fission bank in eigenvalue calculation.
The power iteration method is used and the fission source is converged by UFS.
In the code, I see that fission sites are sampled but I do not understand exactly what is a fission site. Is it related only to the position of fissions from previous generation or is it also including direction and energy of fission neutrons.
When choosing a new fission site for next generation, sampling is done independently for position, direction and energy ?
Thank you for your clarification.
Best,
Thomas
Hi @FroZ and welcome to the forum! A “fission site” does include a position, direction, and energy that were sampled. Here is the data structure that is used:
Fission sites are created at collision sites along a neutron’s path, so the collision sites determine the position. The energy is sampled from the fission spectrum given for whatever nuclide is sampled, and the direction is sampled isotropically.