Chernobyl: The very name conjures the catastrophe that the world feared could happen someday at a nuclear power plant. On April 26, 1986, a power surge caused the core of one of the reactors to explode, spewing a cloud of radioactive steam into the air. More than four thousand people died, as many as a half-million suffered potentially cancer-causing exposure, and the city around the plant became a toxic wasteland in which nothing could live. Before...