the nuclear industry seems to be caught in the multiple "9"s trap : it costs enormous amounts of money (and thus provide motive for taking shortcuts) to build a

the nuclear industry seems to be caught in the multiple "9"s trap : it costs enormous amounts of money (and thus provide motive for taking shortcuts) to build a device with 0.999999999... reliability. That sucks in all the money what could otherwise have been spent on multiple, yet built to less "9"s and thus cheaper, additional levels of protection, say several more metal containment/enclosing vessels instead of the current 2 - the reactor's vessel itself and the containment structure. There are a lot of examples when the same or less amount of money spent on cheaper components allowed to organize them into more reliable or performant system.