On a visit to the site of the Fukushima nuclear plant meltdown in Japan in February, Representative Alexandria Ocasio-Cortez of New York did something refreshing: She discussed radiation exposure and nuclear waste without fanning fear. The radiation she got from her visit — about two chest X-rays’ worth — was worth the education she received on the tour, she told her 8.6 million Instagram followers. She then spoke admiringly of France, which, she said, “recycles their waste, increasing the efficiency of their system and reducing the overall amount of radioactive waste to deal with.”