A Shift in Nuclear Powers, Popular Science

We recently published a data visualization on Nuclear Reactors' constructions and decommissioning over time and in several countries on the September Issue of Popular Science.
The main point of the data visualization is to illustrate how the world's nuclear reactors are aging, and being decommissioned more quickly than they're being built, producing a “nuclear energy gap”.
you can find a high-res pdf of the visualization here.








As Jessie Geoffray from Popular Science wrote on the introduction:
“Nuclear energy provides 11 percent of the world’s electricity, but most reactors are now decades old. Many are approaching—or have surpassed—their initial 30- to 40-year lifespans (though upgrades can extend their lives to 60 years). Early nuclear adopters like France and Germany are curtailing their programs, even though analysts—including the authors of a recent report from the Intergovernmental Panel on Climate Change—say nuclear is necessary to keep worldwide carbon emissions in check. Emerging economies may take up the mantle: Planned reactors in China, Russia, and India could keep the world’s inventory stable”

Nuclear is particularly important because it's a steady power source, unlike wind and solar, which are variable, thus the main visual features of the graphic makes this point.

Some curiosities around:
“Since late 2012, the U.S. has announced the retirement of five reactors, and several planned units are currently on hold.

Just before the Fukushima disaster in 2011, nuclear power provided about 29 percent of Japan’s electricity. As of late 2013, all of its reactors were shut off and producing no power—though many were still technically operational. Japanese utilities are importing natural gas and oil to satisfy electricity demand.

Russia has aggressively pursued nuclear power, following a post-Chernobyl hiatus that lasted more than a decade.
In June, the French prime minister Germany introduced a bill that would cap nuclear at its current capacity.”

And, as you can see, there isn't a growing nuclear energy gap in China
(online version here).

We purposely didn't highlight those reactors which melted down, for Russia and Japan we wrote some notes on it above the countries,but we didn't want to focus the pice on that: visualizing those cases would have eventually shifted the topic and focused the attentions of the readers on those few milestones.

As for the decommissioning we grouped decommissioning and permanent shutdowns and treated them as events (and not as periods): this, to avoid confusions at first since we already have so many statuses, plus the decommissioning of a reactor is the signal of its status of dismiss.

As we approached the visualization a timeline approach seemed the most appropriate to show the reactors' aging over time, we decided to visualize all of the countries in a comparable way. 
The images show an overview of the steps from the first sketch to the final piece.