I think our biggest disagreement is what counts as a nightmare scenario. For instance, while 3 Mile Island did involve a radiation release, it was very small. I don't consider another 3 Mile Island to be a nightmare scenario. And I believe that we learned from 3 Mile Island, so something that bad is highly unlikely, although within the realm of possibility.
Fukushima involved a major earthquake, a tsunami, a lack of power, and a plant that had reached its end of life. Even with that combination of bad luck, less radiation was released than Chernobyl. I don't worry about a similar disaster in the United States because we simply don't have many nuclear plants in areas that can actually be hit by tsunamis. Clearly we have reactors in earthquake-prone areas (and others in tornado-prone and hurricane-prone areas), but the plants were designed with those dangers in mind. While it is possible to have a similar disaster in the US, the chance of it happening is small enough that I don't lose sleep over the risk.
Chernobyl is the worst nuclear power plant accident ever. Chernobyl's design was below Western standards of the time, and well below current Western standards. There is no plant in operation in the US that could have a disaster as large as Chernobyl. And there is certainly no chance of a disaster larger than Chernobyl. It is literally impossible (for a larger disaster to occur).
Fukushima involved a major earthquake, a tsunami, a lack of power, and a plant that had reached its end of life. Even with that combination of bad luck, less radiation was released than Chernobyl. I don't worry about a similar disaster in the United States because we simply don't have many nuclear plants in areas that can actually be hit by tsunamis. Clearly we have reactors in earthquake-prone areas (and others in tornado-prone and hurricane-prone areas), but the plants were designed with those dangers in mind. While it is possible to have a similar disaster in the US, the chance of it happening is small enough that I don't lose sleep over the risk.
Chernobyl is the worst nuclear power plant accident ever. Chernobyl's design was below Western standards of the time, and well below current Western standards. There is no plant in operation in the US that could have a disaster as large as Chernobyl. And there is certainly no chance of a disaster larger than Chernobyl. It is literally impossible (for a larger disaster to occur).