What you will need is a (reputable) school that offers engineering degrees online. As far as I know, there are only 2 ABET accredited engineering programs available online. ASU offers electrical engineering 100% online. UND offers chemical, civil, electrical, and mechanical online, although you have to go to the school for 1-2 weeks in the summer for labs. I know TA covers the full tuition for UND (although you're on your own when you have to go out there), but I'm not sure about ASU.
Once you get through that Penn State offers a MS in Nuclear Engineering online.