Nuclear power has always been controversial, but the debate perhaps has never been so polarized. One camp argues that the planet needs it more than ever and champions the rapid expansion of capacity in countries such as China and India. The other side says now’s the time to get rid of nuclear energy and celebrates the shuttering of reactors in the U.S. and Europe. It’s a collision between concerns over global warming — which give nuclear power appeal as carbon-free energy — and anxieties about safety, which were heightened by three reactor meltdowns at the Fukushima plant in northern Japan after an earthquake and tsunami in 2011.