On a flat, low-lying island nestled in crisp waters off the west coast of Finland, the first nuclear power plant ordered in Western Europe since 1986 is inching toward start-up.

Over 4,000 builders and engineers are at work on the sprawling Olkiluoto 3 project, whose turbine hall is so cavernous it could house two Boeing 747 jets stacked on top of each other.

When it is dark, which in winter