EPR was made after decades of mostly stagnant French nuclear reactor orders. A lot of the people who worked on the reactor projects have since long retired. Lots of institutional knowledge was lost.
The Olkiluoto EPR nuclear reactor project in Finland has been nothing but an unmitigated disaster. It is supposed to finally begin operations in February 2022. Construction began in 2005. That is 17 years to build a nuclear reactor.
I don’t know what it was like in the 70’s nuclear heyday, but let me tell you my short experience in the 2000’s.
The early “nuclear renaissance” looking for CO2-free power generation coincided with the end of the useful life of early reactors. Now there is a lot of work to undertake to extend the life/upgrade power plants. This work pulled a lot of old engineers out of retirement, since basically nothing was built since the 70’s/80’s outside of China.
Everything taking a long time because it’s these old guys teaching young people half the time. The other big time suck is half the suppliers are out of business or not making that part anymore. So one way or another you are paying up to get what you need. However because of the “green” aspect, everyone is willing to invest this time and money.
Then Fukushima happens and the companies fire everyone once again and work pace is crawling