Multiple-unit probe pusher and system for driving eddy current inspection probes in the heat exchanger tubes of a nuclear steam generator

A system for driving inspection probes through heat exchanger tubes in a nuclear steam generator, said system comprising:

• a) a multiple-unit probe pusher including a housing containing a plurality of independently actuable drive means and a same plurality of inlets and outlets passing through said housing, thereby providing a plurality of probe drive paths, each having an inlet, an outlet, and a drive means;
• b) a control means for independently actuating each of said plurality of drive means of said multiple-unit probe pusher;
• c) a multiple-unit probe storage means located outside of the nuclear steam generator including a plurality of probe take-up means for feeding and receiving a probe to and from said multiple-unit probe pusher, wherein there is at least one take-up means for each probe drive path;
• and
• d) a guide means for receiving and directing selected probes from any one of said plurality of probe drive paths from said multiple-unit probe pusher to selected tubes for inspection,
• wherein said guide means is incapable of receiving all of said probes simultaneously such that at least one of said probes and its associated drive path is immediately available as a spare in the event that one of the selected probes fails.