Pretty much what I figured. An email the other day came across my desk that talked about having work classified at secret or above. So, I decided to go to my mentor group and ask about clearances in academia. Pretty much the same as I'd been led to believe. I could do a lot of work, a promotion committee would never see it, and that would be sad. Not as career ending since I have tenure, but not good for the next step. The other piece is that they have done dissertations (I'm a student and faculty) that were classified or had that kind of information. They produced redacted versions for publication. That though was a anecdote the veracity can't be checked unless we knew which one it was.