I tell you what might help. If you can find any info about the specific plant you are going to, that would probably help. Like knowing what components do what and where they are. Big things like where the core spray pump is and the basic function of core spray. You will get all that as an NLO, but when the instructor starts rattling off stuff it is helpful to already know a bit about the thing so you aren't reeling from the info. A lot of it is visualization, so if you have a correct vague vision to start off with, it could help. Coming from the Navy straight into NLO I had an idea about most stuff, but when they started talking refuel activities I totally got lost because I couldn't visualize what they heck they were talking about. Even if you can't find info about the specific plant, you could just do basic research on a BWR or PWR and most of the stuff will fit. Everyone has a fuel pool, right? Well what are the basic functions of a fuel pool? Stuff like that, gives you a basic "anchor point" to start learning from for each major system. don't go too in depth though it will increase the chance you are learning incorrect information.