Slip a large enough conventional device under the fuel coolant tower, then one or two next to the reactor to breach it. You will end up with wind dispersion of dirty material and a meltdown which will effect the local area for 10,000 years. That's pretty much the scenario most likely to happen if it was attempted. A MIRV would be more efficient to devastate a region or a single load warhead for half a state. Setting off a nuke at a nuclear power plant is over kill and a dumb waste of effort. The plant is not in a high value area and the single warhead itself has greater damage potential.
No one wants to nuke anything, a single nuke by a bad actor would start a chain of events that would not work out well for for the third world, middle east, NKorea and any small bad actor nation once the first world used the incident to clamp down on the rest of the world. You can already see the spheres of influence the first world nations would clamp down on by looking at the current globalization trade treaties. And unless the EU wakes up, no nukes will be needed to had Western Europe over to Islam. A nuke event would wake the world up and get in the way of the current great under reported migration event.
