It was a warm spring evening as I set off in a kayak from a boat ramp in Middletown, Pennsylvania, about an hour north of Baltimore, into the still waters of Swatara Creek.A family of ducks, with a dozen ducklings, paddled in the river. A pair of kayakers, father and son, came in off the waterway, dragging their boats up and laughing with each other. Children in their bathing suits splashed in the shallows at the boat launch.As the sun set, illuminating the clouds, I passed around a bend and, beyond the trees, saw the four enormous cooling towers of the Three Mile Island nuclear power plant.It was 40 years ago, in 1979, that a partial meltdown at Three Mile Island triggered the evacuation or flight more 140,000 people from south central Pennsylvania. The incident – and the authorities’ bungled response to it -- generated so much fear that the nuclear industry never recovered in the U.S.