Student or Learner
Please set me clear on the following in red.
When most people argue about nuclear energy, they're arguing Three Mile Island and 1970s technology---which is about when the US nuclear industry ground to a halt. But research didn't die off, just new construction. We're two generations beyond that earlier tech, and the changes have been massive.
Is this saying "they just constructed new nuclear plants"?
Sort of. It was just the new construction (of additional power plants) that died off (stopped).
So, since then, no or very little new construction of power plants, but the nuclear research continued.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.