Plenty! Among other things, they literally decay over time, and that's fundamental to and completely inseparable from the way they work. Plus for some reason people always want them to be smaller and cheaper and more reliable.
Plus, we're not allowed to actually blow them up to test any more, so they do all that in simulation on the world's biggest supercomputers. This leads to work in HPC system software, kernels, compilers, programming languages, HPC libraries, and so on.
probabl a lot of that stuff is very sensitive but are there any good books people can recommend on that type of work at the intersection of programming/ (nuclear) weapons development?
