It is typically required for radiograhpers and users of fixed and portable gauges (all examples of folks using using sealed sources) to attend some form of training. The extent is typically dictated on the users materials license. It seems your potential employer would send you to this training.......but oh well.
Try Ohmartvega in Cininnati, OH. And I think Dave Warren was looking for a 40 hour course a while back, try doing a search of his posts or for 40 hour courses.