International Fusion Materials Irradiation Facility (IFMIF)-like fusion neutron source (FNS) produces fusion-like neutrons by injecting a 125 mA/40 MeV deuteron beam into a liquid lithium target in order to elucidate fusion neutron irradiation effects on fusion reactor materials. The engineering design activities for the FNS were performed by Japan during 2020–2025 under the IFMIF/Engineering Validation and Engineering Design Activities (EVEDAs) project. The activities consist of five tasks: (1) tritium migration estimation, (2) erosion/deposition modeling in the liquid Li target loop, (3) accident analysis in safety, (4) study on the optimization of the Li-Oil heat exchanger, and (5) use of LIPAc as testing facility. Through engineering design activities, this study evaluates the radiological risk for both workers and the public in the FNS facility and suggests radiological safety measures.