(Disclaimer - I don't work at Hatch or for Progress)
Generally, an engineer at a nuclear plant will get a salary that is the same or higher than the other engineering scales in the utility. The utility pay scales I have seen (I've worked at two utilities) were at the upper half of the ranges you see in online estimates (salary.com, etc.). Utility benefits are typically very good compared to the private sector as a whole.
As far as job opportunities, your options are pretty much unlimited as far as the utility goes, depending on your interests and skills. The closer you are to operations (Ops versus Shift Technical Adviser, STA versus system engineer, system engineer versus design engineer) the more jobs on site you will be qualified for. Most utilities have internal job postings, where you can transfer from one group to another. A technical understanding of the plant (which you get through engineering) will never hurt you in your career (it may not help, but it certainly won't hurt in the nuclear field). Some companies will also pay at least partial tuition for a MS/MBA degree if you want to go that route.
Between the upcoming wave of retirements, and the potential for some new plants to be built, there should be plenty of opportunities for a young engineer to do well in the next decade or two.
