I love to hear good news like this. It's tough for kids out there these days. Even with college or military background. I've had great luck hiring ex military guys, and would try to get them for their discipline and just because I appreciate their service. Its pretty pathetic to see a good kid come looking for a job who has just served his country and no one will hire him.
Anyway, NDT testing is good experience to have. To tie it in to what other people have said about the oil and gas business, there is a lot of NDT testing that needs to be done in gas plants and refineries for mechanical integrity programs. Its the kind of experience that lends itself to starting one's own business. Almost all those facilites use 3rd party contractors for NDT testing. Get set up to be the contractor for a few facilities and you would be making huge bucks. Oil companies pay out the ass for that kind of service. To do it right you would need to be able to analyse the data and get a pressure vessel inspector cert etc, but its all doable, looking at the big picture.