Idea to isolate harmful reactors.

The reactor cores are the threat right now. They can become similiar to an armor piercing tank round, when they are in their final stages of meltdown.

If they meltdown in their current conditions, the ultra-toxic molten goo, will run in many a direction. This will make clean-up near impossible.

Now, if you use a small, tactical warhead, delivered by a ground penetrating system, you could create a cavern below the reactors of your choice.

You could then choose to keep the caverns there as a waste run off option, or you could further compromise the integrity of the ground beneath your respective reactor, and have it drop into the cavern.

You could then pour concrete into this cavern, preventing most of the contaminates from reaching the ocean water nearby. Not to mention it will never see the light of day again.