Going Nuclear Without Blowing Up

In September, 2022, Rafael Mariano Grossi, an elegant Argentinean diplomat with tousled salt-and-pepper hair, led a convoy of nuclear experts toward the sprawling Zaporizhzhia power plant, in southeast Ukraine, which had been seized by Russia in the early days of its invasion. It is the largest nuclear facility in Europe and the first ever to be on the front line of a war. The dangers of a radioactive catastrophe were unprecedented. Explosions near the site had already damaged a high-voltage power line; Ukraine feared the failure of cooling systems that prevent nuclear fuel from melting down. Neither Ukraine nor Russia had promised full access to Grossi, the director-general of the International Atomic Energy Agency, the U.N. watchdog that has a mandate to secure nuclear plants and report