[jjk166]

It doesn't matter if it's an evolution or a revolution - a change of any sort means new tooling to produce the components, new procedures to assemble them, new analysis to certify that they will all work together, and new training for everyone involved to do all the above.

[natmaka]

All this was known before starting the building process, and the builder planned to deliver the reactor in 2012. It is late (right now: not delivered) mainly because project management and quality insurance were abysmal: https://en.wikipedia.org/wiki/Flamanville_Nuclear_Power_Plan...