Containers for storing sealed sources
A sealed radioactive source is considered to be waste when, because of decay, it is no longer sufficiently radioactive to be used as originally intended. Sealed sources can contain a wide range of radionuclides: 192I, 60Co, 137Cs, 90Sr (short-lived); 226Ra, 227Ac, 235U, 238U, 238Pu, 239Pu, 242Pu, 241Am, 244Cm (long-lived alpha-emitters). The majority of spent sealed sources contain alpha radionuclides