A source changer may contain multiple sources, typically housed in U-shaped tubes. In addition to its function as a transportation package, a source changer is used to move sources either from or to an exposure device. Although the remainder of this appendix specifically addresses exposure devices, the review of a source changer is similar. A sketch of a typical radiographic exposure device is presented in Figure A1-1 . The principal safety function of these packages is to retain the radiographic source and to provide gamma shielding.
Containment is provided primarily by the special form source itself.
These packages do not contain fissile material. A lead or depleted uranium shield provides gamma shielding. A securing lock mechanism positions the source pigtail within the S-tube in the shield during transport to prevent high radiation fields and radiation streaming. A safety plug assembly at the opposite end of the tube provides a redundant mechanism to prevent movement of the source. The housing, foam, and other structural materials protect the shield and S-tube from damage.