# Power Peaking Factor

Hi forum,

I’m relatively new to OpenMC and working on a research about reactor’s power peaking factor. Could I calculate power peaking factor (both radially and axially) from fission-q-prompt tally score?

Best regards,

Hi @fadilnaufalwahas and welcome to the forum. I would recommend using the `fission-q-recoverable` score because it includes energy from delayed neutrons, photons, and electrons whereas `fission-q-prompt` does not. Be aware that these scores don’t account for non-fission energy deposition (such as production of photons from (n,γ) reactions and their subsequent deposition), so if you really want to do this rigorously, you need to run a coupled neutron–photon simulation and tally the `heating` score.

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Thank you @paulromano
Referring to the posts you made [1] [2], I would like to know if I understood the calculation. The power of fuel (in watt) could be calculated by:

P (watt) = ( F * Pr * (vf / f) * c ) / ( Q * keff )

with
F = tally `fission-q-recoverable` (eV/source)
vf = tally `nu-fission` (neutron/source)
f = tally `fission` (fission/source)
Pr = known reactor power (J/s)
Q = 3.2E-11 J/fission (for U-235)
keff = neutron multiplication factor (neutron/source)
c = 1.6E-19 watt.s/eV

Is my interpretation correct?

Best regards,