As Japan began its workweek Monday morning, the trains ran exactly on time, the elevators in thousands of Tokyo high-rises efficiently moved between floors, and the lights turned on across cities with nary a glitch.

What makes this Monday so remarkable is that for the first time in four decades, none of the energy is derived from a nuclear reactor.

Over the weekend, Japan's last remaining nuclear reactor shut down for regular maintenance. In the wake of the Fukushima Daiichi nuclear disaster, reactors have not been allowed back on. Japan is now the first major economy to see the modern era without nuclear power.