@steephie
Turning Pu-239 into a nuclear bomb is not a trivial process. Making a dirty bomb out of Pu-239, or even U-235 is certainly possible, but the reality is that there is already tons of this stuff all over the ex-Soviet bloc, if the terrorists wanted it. Further more, it's possible to use Th-232, which is OK for NPP, but not good for bombs.
Yes, they would be great target for terrorists, but, honestly, so would any power plant. Have any NPP in the world been the victim of a successful terrorist attack?
And, honestly, we shouldn't build NPP because we're worried about terrorists? That's letting them win, man!