But if we're going to talk about the 3 accidents, we should note that they are quite different.
Chernobyl was a positive pressure reactor. Only the Russians were ~~dumb~~interested in building these. Everyone else was afraid because their ability to explode and instead chose reactors that couldn't explode. The accident happened not just because of this, but because the xenon spike and not a great understanding of the science.
TMI had a bunch of things go on at once. Relief valve stuck open but indicating close. Not enough water during SCRAM. Turning off ECCS due to bad indications. Then the hydrogen explosion. Resulting in about a dental x-ray's worth of radiation for a limited number of people. We now have hydrogen absorbers and have upgraded reactors to ensure these events don't happen again. [0] (this channel also talks about all the events).
Fukushima was caused by the largest earthquake and tsunami ever recorded in the region (so lower bounding to 1k year event) and one of the largest ever recorded anywhere. The reactors were designed to withstand quakes and tsunamis. The tsunami and earthquake were much larger than anyone expected to ever happen in the region. Reactor got destroyed and it is hard to track where all the material went, which is why they have the region closed down (background radiation levels aren't so bad, but you don't want to risk consumption of reactor material. Similar to why the surrounding area of Chernobyl is closed).
The reason I bring all these up is because we should note that even Gen 2 reactors have been retrofitted with improvements from these events, and have been this way for a long time.