I had no idea where in Nevada Yucca Mountain is, which is why I asked.

There is no comparison between the Japanese bombings and the amount of waste planned for Yucca Mountain. It's tens or hundreds of times the amount released in the Chernobyl or Kyshtym disasters. A geological event that disrupted the repository beyond repair so the waste could break loose would make half the US uninhabitable and have global consequences once it got to the oceans. It might take decades but there wouldn't be a thing anybody could do about it.

So far, the only contained major nuclear accident is the Kyshtym one (Lake Karachai) and that's just by geographic fluke. Nobody has a clue how to improve the containment for the longer term, or has any plans to try. Meanwhile we have a lakeful of sludge that will kill you with an hour's exposure just waiting for a change in hydrology to dump it all in the Arctic Ocean.