Power plants are among the first targets in a war, and a nuclear reactor blast by a weapon would release its radioactivity accumulated in normal use just as an accident like Chernobyl does. A country with many reactors transformed into dirty bombs would be uninhabitable. Unfortunately, weapons capable of bursting the domes of a nuclear reactor already exist or are easily extrapolated. Description of a kinetic energy penetrator - the small version designed to break the armour of a battle tank: http://en.wikipedia.org/wiki/Kinetic_energy_penetrator such arrows weigh 5kg of uranium or tungsten and impact at 1.5km/s, piercing 0.3m of steel. More speed makes kinetic penetrators more efficient. They travel then outside the atmosphere and fall on the target from above. Such penetrators are already designed; they're said not to be in operation because of treaties. For instance, starting at 3km/s and 45°, a penetrator would climb to 200km, travel 800km, and fall at 3km/s in the atmosphere. A single-stage rocket with solid propellants gives this initial speed to about 1/4 of its lift-off mass. A 20t rocket, fitting on a truck, a fishing boat, a submarine... would propel a 5t penetrator. Such a massive, plain and passive arrow is extremely difficult to destroy or divert. Atmospheric re-entry wouldn't brake it, as 10km air aren't heavy compared to several meters steel, and the arrow is pointy. And it's about as easy to build as a V2 (but 65 years later), much easier than the rockets Iran has already built, as an example. The higher speed more than compensates the density of an arrow of steel instead of uranium. With 1000 times more mass and a higher speed, it pierces an armour more than 10 times as thick, or over 3m armour steel - much thicker than the domes of existing or planned reactors. So I urge everyone to find an affordable way to protect future reactors (and existing ones, even more difficult) against such weapons, or bigger ones. If no way exists, nuclear power plants are such a huge military weakness that a country better would have none.