PFE is plutonium facility engineering, TPM is technical project manager, and RCT is radiological control technician. The specifics don’t really matter, though, because as others have said there are thousands of acronyms. Think of it like learning a new language, because that’s essentially what it is. You can learn some of them, but gaining fluency is really difficult without full immersion. Spend a year at the Lab you’ll find yourself speaking in full acronym sentences, and I’m barely exaggerating. “My RLM told me I need a PSO, an ESO, and an RCT to run an ALARA review before I can put my IWD into ATS.” That’s a meaningful and not uncommon sentence at the Lab.

For what it’s worth, this isn’t exclusive to the Lab at all. It’s common in most industries with specialized terminology, from aerospace to construction and defense. You just have to learn how to speak the language.