Had you read my link you'd know that "fault tolerant" means the system which continues to do its job even when some components of it already failed. The system designed to "fail early" simply fails by default. There's simply no attitude of "do as much of the work no matter how many components already failed" or "making my part failing as seldom as possible." Not the mention actually designing the active recovery process, the complete opposite of "fail early":

https://www.youtube.com/watch?v=KgTs8ywKQsI

Compare that approach with the handling of the water in the Fukushima electrical generators, situated on the edge of the ocean.

But even with all the possible care, accidents do happen. Some possibility will remain unaccounted.

So the only good approach is to have so little nuclear weapons that the accidents, when they happen, and they surely will happen, still don't destroy the humanity. The goal must be "fault tolerance" on the civilization level.

Or there won't be any civilization left.

The same stands for handling the global warming.