[mikeash]

This is something of a nitpick, but they really ought to refer to it as a nuclear bunker, not a fallout shelter. A fallout shelter is just something that can shield people from fallout radiation. You need thickish walls but nothing too special. Some places in the US you can still see the "fallout shelter" sign on schools and such. However, it doesn't offer much protection from a nuclear blast. The intent is that the survivors of a near miss would stay in fallout shelters for a few days after the explosion to wait out the worst of the radiation.

It sounds like this thing is a purpose-built bunker built to withstand a nuclear explosion, so much more robust than the title would imply, at least to me.