Re: More on those lousy missiles.
Also, the major heat source in a nuclear plant is the cooling tower, water outlet, or whatever they are using to dump waste heat. The actual containment building has no real heat source for a heatseeker to home in on. Knocking out a cooling tower might shut down the plant for safety reasons, but would do no serious damage to the nuclear core itself.
An antiaircraft missile would not be the weapon of choice for this.