We are a university lab and so we rarely do work specifically for any government entity. There is the odd experiment for NASA where they want to know the effect individual medium-energy heavy ions can have on things, and we are very well setup to do those. But to address a common misconception, we don't work on bombs or anything related to bombs. We may be said to work on things that are related to things that are related to nuclear weapons, but we are in nuclear physics after all, and as we all know you are probably only five degrees away from Kevin Bacon.
I have to admit that I find this a daunting task, mainly because I don't know who you are (assuming you exist). Generally writers have the luxury of a bit more information about who their readers are likely to be. It's like being a teacher on the first day of class and walking into a room filled with a random selection of students from all grade levels. How do I talk to them about physics?