I worked on airframe design in the 1970s. The ethos of design to withstand failure was well-entrenched then, and goes back a long way in the airframe industry.
The key idea is nobody has managed to design parts that won't fail. But they have figured out how to design highly reliable systems out of parts that fail.
Sure. The American nuclear industry kinda caught up with that after Three Mile Island, when they figured out that one nuclear accident put them all at risk. They developed an extreme culture of safety after that.
Current designs use lots of redundant safety systems. New designs depend more on simple physics...eg., fuel that expands enough when it heats to damp down the reaction, or large quantities of coolant with very high thermal capacity and conductivity. At Argonne's IFR project, they shut down coolant circulation and electric power, and the reactor quietly shut down with no damage.
The key idea is nobody has managed to design parts that won't fail. But they have figured out how to design highly reliable systems out of parts that fail.