Sealed radioactive preparations emitting gamma radiation (e. g., 192Ir — and 60Co-sealed sources) are produced by placing reactor-irradiated metal pellets or cylinders into steel capsules, followed by sealing by welding. The overall activity
of the assembled source can be controlled by using the appropriate number of the individual pellets/cylinders of known (measured) activity. The activities of such gamma-emitting sealed sources are extremely high; they are in the range of TBq (terra-Becquerel).

Beta-emitting (e. g., 137Cs) sealed sources are produced by chemical processing of Cs extracted from fission mixtures to CsCl, followed by embedding these particles into glass beads and finally by sealing glass beads into metal capsules. Alpha-emitting (e. g., 241Am) sealed sources are produced by extracting the given radionuclide from fission mixture and deposited onto foils.

Sealed radiation sources are used both for medical and for industrial applications. In medical applications, external radiation therapy and brachytherapy, while in industrial applications radiography (e. g., testing welding seams) and gamma sterili­zation are generally known.