Transport groups, radioactive materials

For transportation Surface-contaminated objects (SCOs) are of special interest SCO means a solid object which is not itself radioactive but which has radioactive material distributed on its surfaces. SCO is classified in one of two groups ... 

Transportation instmctions require DOT Hazard Class in which materials are divided into the following classes 1 - Explosives, 2 - Gases, 3 - Flammable and combustible liquids, 4 - Flammable spontaneously combustible solids, 5 - Oxidizers organic peroxides, 6 - Poisonous infectious materials, 7 - Radioactive materials, 8 - Corrosives, 9 - Miscellaneous. In addition UN number and packaging group is also given. 

The U.S. Postal Service has many restrictions on the shipment of radioactive materials by mail for example, no package may contain more than 0.1 millicuries of the most common tracer radionuclides (Transport Groups III and IV, see Table App. 3.2), and the exposure rate at the surface of the package must be less than 0.5 milliroentgens per hour. The package must also have no significant surface contamination (defined as less than 220 dpm per... 

---