Release fraction

For discrete or single events the airborne release fraction (ARF) is the coefficient used to estimate the amount of radioactive material suspended in air as an aerosol and thus available for transport due to a physical stresses from a specific event.

For the mechanisms that continuously act to suspend radionuclides (e.g., aerodynamic entrainment), the airborne release rate (ARR) and the release time are required to estimate the potential airborne release fraction from the postulated event conditions:

ARF = ARR * release time