A proof-of-principle experiment for the irradiation testing of candidate reactor materials utilizing fast neutrons from a cyclotron as it produces clinical Positron Emission Tomography (PET) isotopes is presented. The reaction 18O(p, n)18F results in 18F for use in the radio-pharmaceutical fluorodeoxyglucose, as well as a significant flux of by-product fast neutrons. In this work, wrought forms of alloy Inconel 625 and its additively manufactured counterpart were placed in near proximity to the 18F producing cyclotron targets. The microhardness values were tracked periodically for over 25 weeks as the samples acquired fast neutron dose; up to approximately 9 × 1015 1-MeV-equivalent n/cm2. Hardness values for the wrought sample evolved with dose, by as much as ∼15% throughout the experiment. However, the additively manufactured samples remained relatively unchanged under identical dose. These results demonstrate the promising feasibility of using this irradiation method to explore mechanical property changes in nuclear-relevant alloys under low-dose conditions.