Radiation safety considerations for ISAC, the accelerated radioactive ion beam facility at TRIUMF

There has been a steadily growing worldwide interest in generating accelerated beams of unstable nuclei for use in a variety of applications such as nuclear physics, nuclear astrophysics, atomic and condensed matter physics, and medicine. At ISAC, an intense proton beam from the TRIUMF 500 MeV cyclotron bombards a thick target which is raised to high temperature. Radioactive atoms are in this way driven off into an ion source and the ions are extracted at a suitable potential. A high-resolution mass analyzer then separates the undifferentiated ion beam and a particular species is selected. These low-energy ions can be delivered to experiments directly or a post-accelerator can further accelerate them. The most severe radiological problems arise out of the deliberate generation of volatile activities in the target/ion source only a small fraction of which are extracted as a usable ion beam. A wide spectrum of activity must be addressed as it is desirable to use a variety of target materials up to and including Z=92. This paper describes the methods for calculating the radioactivity production, the means of limiting and containing the contamination and the equipment and procedures for handling the highly radioactive targets.