[natmaka]

> They're not the same buildings

Not exactly the same but same generation, architecture and design (Westinghouse), slightly (not fundamentally) enhanced. Stating that new features add such a large amount of work (relatively to the total amount) that it compensates for the knowledge gained thanks to previous projects is debatable.

Between the oldest (CP0) and newest (N4) aren't the key differences limited to a same machine and command room shared (CP0) or not (N4) between reactors, scale (CP0's nominal power being lower), and details related to fuel rods and pipes? In which way are they dissimilar to the point of absorbing the effect of gained knowledge and adding such delays?

Even the shiny new EPR is a mere enhancement of the core design dating back ~1970.

Sorry, I don't know enough about SpaceX to have an opinion.

[pyrale]

> Even the shiny new EPR is a mere enhancement of the core design dating back ~1970.

If you push this logic to its end, even a tesla car is a mere enhancement of the electric cars produced in 1900. There is no breaking change like wings, the ability to teleport or supersonic speed.

If you look in details what changed between CP0's and N4's though, there's quite some change [1]: N4's have a double containment enclosure while CPO's have a single one, the vessel contains 400m3 vs. 270m3 and weights almost 50% more, sustains 15 mor bars and 15 more °Cs, and it produces almost 60% more power.

Enough progress for Westinghouse to value Framatome's experience to the point that they became a partner, stopped paying license fees and earned the right to export their design[2].

[1]: https://fr.wikipedia.org/wiki/Centrale_nucl%C3%A9aire_en_Fra... [2]: https://www.lemonde.fr/archives/article/1981/01/24/framatome...

[natmaka]

Before the N4 there is no question, read page 12 (first paragraph) and 13 (first paragraph): https://archive.wikiwix.com/cache/index2.php?url=http%3A%2F%...

The N4 double containment is a mainly quantitative change, as are all the other changes you mentioned: the very architecture remains the same, as do the associated exploitation processes.

Those modifications were big enough to justify seeing the N4 as a "new design" because the French worked hard to master this design, and since 1981 (Nuclear Technical Cooperation Agreement, NTCA) Westinghouse & the French formally exchanged know-how. Moreover Westinghouse didn't work on the N4 and it escaped the Westinghouse license (which expired in 1992). However the very design isn't disruptive. As for this approach efficiency the note #17 seems pertinent.

The newest design ('EPR') also is a mere evolution, as officially stated: https://www.irsn.fr/savoir-comprendre/surete/presentation-hi...