The six-factor formula is used in nuclear engineering to determine the multiplication of a nuclear chain reaction in a non-infinite medium.
Symbol | Name | Meaning | Formula | Typical thermal reactor value |
---|---|---|---|---|
Thermal fission factor (eta) | neutrons produced from fission/absorption in fuel isotope | 1.65 | ||
Thermal utilization factor | neutrons absorbed by the fuel isotope/neutrons absorbed anywhere | 0.71 | ||
Resonance escape probability | fission neutrons slowed to thermal energies without absorption/total fission neutrons | 0.87 | ||
Fast fission factor (epsilon) | total number of fission neutrons/number of fission neutrons from just thermal fissions | 1.02 | ||
Fast non-leakage probability | number of fast neutrons that do not leak from reactor/number of fast neutrons produced by all fissions | 0.97 | ||
Thermal non-leakage probability | number of thermal neutrons that do not leak from reactor/number of thermal neutrons produced by all fissions | 0.99 | ||
The symbols are defined as: [2]
The multiplication factor, k, is defined as (see nuclear chain reaction):