People forget just how much the US itself has in the way of ruins, old tunnel systems, shelters, etc. The Manhattan Project was able to run beneath a major city like Chicago because of the sheer scope of modern-ish ruins. It's also analogous to the catacombs of Paris, someday the tube system will be a ruin just like that, and probably a new city will be built on those ruins.

They use something called a refractory material to line the various containers, and these are a bit like the tiles on the space shuttle, very VERY resistant to heat. They do need to be replaced on a regular schedule, but they keep the containers from melting on the surface.

Specifically the torque converter uses a fluid coupling: https://en.wikipedia.org/wiki/Fluid_coupling

It's a good read!