Good morning everyone, can someone explain the difference between HEATING and HEATING-LOCAL tallies?
When a neutron undergoes a capture reaction (n,γ), the energy released is split between the recoiling nucleus and the emitted gamma photon. HEATING uses KERMA coefficients that explicitly subtract out the photon energy, expecting it to be deposited wherever the photon actually transports — so if you’re not running coupled neutron-photon transport, that energy is never scored at all. HEATING-LOCAL uses a different set of coefficients that assume the photon is absorbed on the spot, folding its energy directly into the local tally regardless of where it would actually travel.
The distinction matters because a gamma photon can travel a significant distance from its birth site before depositing energy — or escape the geometry entirely. HEATING is the right choice for coupled neutron-photon simulations where photons are explicitly tracked, while HEATING-LOCAL is intended for neutron-only runs where you still want a complete energy deposition estimate without simulating photon transport.
For a more detailed breakdown of how OpenMC handles this under the hood, see the Energy Deposition section of the OpenMC docs.
Thanks for your explanation. Excuse me for this stupid question: what is the best way to approac the number of fission per second between kappa-fission and heating -local?