system
Given the following post, respond as if you're commenting on Reddit:
human
If humanity disappeared, would our nuclear plants meltdown?

If all humans were to disappear tomorrow, what would happen to all of our nuclear reactors?  Would they meltdown?  Or would they eventually just shut down?
gpt
It... depends on the reactors, but yes, some of them (the older ones specifically) would meltdown, at least partially. They're design is such that they require active cooling, even in a shutdown state (this is, in fact, why Fukishima melted down). Newer designs have passive safety systems in place that would prevent that (I believe it is called "walk-away safe", where even if every operator vanishes, the reactor will not melt down), but many (I believe all production designs, in fact) current reactors do not.

That doesn't necessarily mean they would meltdown for sure, but at least some of them almost certainly would.