Can't read the article because it's paywalled but I can't imagine they are actually building power stations with AI, that will just be a snappy headline. Maybe the AI is laying out the floor plans or something, but nuclear power stations are intensely regulated. If you want to build a new reactor design, or even if you want to change an existing design very slightly, it has to go through no end of safety checks. There's no way that an AI or even a human would be allowed to design a reactor, and then have it be built with no checks.