The Chinese CAP1400s took 5 years and that's a new design to them. The first NPP was built in 1951 (ish) and took 18 months from blackboard to grid interconnection. Some designs take longer, others are shorter. Some parts of Vogal were rebuilt 3x times due to the federal government changing the design requirements multiple times during construction. Another challenge is that NPPs are built rarely enough that its hard to be a supplier to the nuclear industry so many parts are custom built per project. That doesn't have to be the case. The idea there is a hard limit of 7 years, sorry...that just isn't so.