Radiation protection calculations for an Am-Be neutron source

When calculating dose rates around an Am–Be source, one typically focuses on the neutron emission. In high activity Am–Be sources, there is a need to consider two additional contributors to the dose: low-energy photon emission from the 241 Am decay (59.5 keV and an additional 4.4-MeV photon from the de-excitation of 12 C* (created by the nuclear reaction of the alpha captured by 9 Be). Usually, the dose rate constants (gamma factors) found in the literature provide a good estimation for the dose rates around a point source. For 241 Am however, the gamma-ray dose constant varies significantly (up to 50%) among different publications and is not reproducible by different methods. In order to overcome this challenge, we performed dose calculations using FLUKA – a multipurpose Monte Carlo code for the transport and interaction of elementary particles and heavy ions. This work shows the calculated dose rates around a 1.85-GBq Am–Be source and compared to analytical calculations and results from radiation measurements. It was discovered that the contribution of the photons to the dose rates is in the same order of magnitude as the dose rates from the neutrons.