Actually, nuclear power plants are designed to withstand failure. Typically there are multiple backup plans to safeguard against failure of any one system. One comment I sometimes hear is, "They had to pump seawater in to cool things down? That's crazy! They should have had a backup plan." It turns out that nuclear plants are intentionally built near bodies of water because external cooling is a backup, should the primary cooling systems fail.

Nothing, however, is designed to withstand systematic catastrophic failure of all of your backup plans.