Nuke expert here.
Most of the generating plants are running on equipment so old that Stuxnet - SCADA controller attacks wouldn't work. This is a priority and has been since 9/11. There is a lot of hype since a virus getting into the office side might reveal sensative things (like dates of nuclear fuel shipments and such) but the controls are pretty old-school. Three Mile Island was a big wake-up call (and this was in 1979).