Canada (mostly Ontario) built 25 reactors in 35 years:
* https://en.wikipedia.org/wiki/Nuclear_power_in_Canada#Power_...
From the 1980s to the 2000s, it took Japan roughly 4-5 years between start of construction and commercial operation for a number of reactors:
* https://en.wikipedia.org/wiki/List_of_commercial_nuclear_rea...