Solar does not replace nukes because nukes are base load, 24 hours. Solar competes with natural gas peaking units. Peaking units are something like $0.18/kwh and solar is nearly 1/2 as much.
Nukes might cost $4/Watt, but they recoup installation costs 4 times faster than solar because they run 24 hours instead of an average 6 peak hours/day. In today's world of scarce capital, $2/Wpeak BOS solar is not cheaper than $4/W nukes because in terms of kWh per day, you only have to spend half as much on nukes because they give 4 times more per day. This is American thinking. In China where the long run is important and game with money are not so prevalent, solar is now cheaper than nukes under all scenarios.