@ulrichOK, I may have been a bit loose there, but there have...

@ulrich

OK, I may have been a bit loose there, but there have been some very drawn out timeframes as the following extracts demonstrate, even up to 43 years. Planning and approval times can be very drawn out but are part of the equation. One of the advantages of new SMR reactor designs is that they are intended to be put in place more quickly and cheaply using pre-fabricated components and standardised designs. SMRs are still in development and evaluation phases and so yet to be proven.

Apparently.Finland's Olkiluoto 3 finally began regular production after a 14-year delay from the original plan. Construction of Olkiluoto 3 began in 2005 (https://www.independent.ie/world-news/europes-most-powerful-nuclear-reactor-begins-production-in-finland/42434756.html)

The average construction time is almost exactly seven years. This figure comes with a large spread, however: while the shortest construction time was just under two years, the longest took almost 43 years to complete! ... What we looked at is the construction time only — it does not take into account the excessive planning and approval phase prior to construction. If we were to want to start construction of new nuclear reactors now, we would also have to take into account this preliminary delay. (https://radiyozh.medium.com/how-long-does-it-take-to-build-a-nuclear-reactor-c2a0c6b29116).