Getting Nuclear Information From 90 Year Old Relative

I have a family member who is above 90 years old who worked on things of a Nuclear nature right out of college [I presume]. Whenever I broach the subject, which is about once a year, at a family function, he usually tactfully steers the conversation away to other things. But I have gotten this out of him. He definitely made at least parts for nuclear "things". He graduated from college in 1940-41 and went on to work for GE in their Neutron Devices Dept. It's those early years, the "beginning years" of the atomic age that I am fascinated by and want to hear his story... whether he was involved, even indirectly, in those developmental stages of the A-bomb. Does anybody have good, solid questions that I can ask him to get his history without having him reveal any classified information? This is crucial to my family history. Edited to add that he did work for GE all his life but it's those first few years right out of college that I am missing. Those are the "mystery years" that I long to uncover for my family history.