The residual activity induced in particle accelerators is a serious issue from the point of view of radiation safety as the long-lived radionuclides produced by fast or moderated neutrons and impact protons cause problems of radiation exposure for staff involved in the maintenance work and when decommissioning the facility. This is a generic study of induced activation in accelerator components, and the same methodology can be applied to any future study of element activation for other accelerators around the world. Taking the High Energy Beam Transport line of the European Spallation Source as a reference we present activation studies of the magnets and collimators due to the back-scattered neutrons from the target and also due to the direct proton beam losses along the beamline.