France is at an energy crossroads. To meet future electricity needs, the country could extend the operating lives of nuclear power plants beyond 40 years, accepting the safety challenges and costs of such a move, or it could change its energy mix, moving away from nuclear power and toward energy-efficiency measures and other energy sources. Until recently, the French government had refused even to examine the possibility of reducing the country’s reliance on nuclear power. But a study by independent French experts suggests that staying the nuclear course would be more expensive and less environmentally beneficial than authorities make it out to be. . .