The mayor of Okuma, a town near the Fukushima Daiichi plant that was hastily evacuated when a huge earthquake and tsunami crippled the reactors’ cooling systems on March 11, 2011, has vowed to lead residents back home as soon as radiation levels are low enough. But the slow pace of the government’s cleanup efforts, and the risk of another leak from the plant’s reactors, forced local officials to admit in September that it might be at least a decade before the town could be resettled...