While working for Bechtel 10+ years ago, I was involved in some refinery work. The difference was night and day. The refineries didn't have accurate drawings, things like valves were unlabeled, procedures were non-existent or outdated, and lots of equipment was broken (hopefully, the refinery industry has improved significantly since then!). The refinery guys were astounded to hear how much safer we thought nukes were.
From an operator's standpoint, they are probably roughly comparable. Both have lots of pumps, valves, heat exchanger, and pipes. Refineries have lots of chemical issues and concerns to deal with, nukes have radiation concerns and lots and lots and lots of regulations, regulators, and people looking over your shoulder. Both have national security/terrorism issues to deal with. Both facilities run 24/7, and represent a significant financial asset for the company involved and the local community.
