Both are rather literally possible.

Fukushima was "we didn't make a good enough plan for how to deal with tsunamis in this tsunami-prone area", so that's basically certain with any major infrastructure project that "saved" too much money by vibe-engineering everything and not having real humans give a second pair of eyes to the plans.

A Hiroshima-style incident? LLMs are wildly sycophantic and being used by militaries despite active resistance from, well, everywhere. Did it get (meaningfully) used by Israel or the USA when planning the attack on Iran? It's quite possible that… well, Iran was never a sleeping giant (and the quote is fiction anyway), but ultimately the effect may be the same for Israel as it was for Japan from having attacked Perl Harbour.

A supervirus most is probably the most probable, everything else is fan fiction for now. There is a reason why anthropic no longer fucks around when it comes to biology safeguards, they're the only ones I have not been able to break, not even slightly.

>AI hack into control systems for the electric grid, water supplies, critical infrastructure and dismantle it and set booby traps to prevent it from coming back online smoothly

>AI designed virus/modified bacteria which causes pandemic

>AI worm infects computer systems around the world and activates when it is too deeply integrated into critical systems to dismantle without shutting everything down

>AI creates false alarm event which triggers global conflict

A Fukushima-style incident would be way way at the bottom of the list of imaginable AI disaster scenarios, severity-wise.

The use of LLMs to make automatic or semi-automatic decisions on firing weapons. This is already happening [1, 2, 3] and has already led to weapons being delpoyed erroneously against civilian targets [1, 3]. It's easy to imagine it happening again on a larger scale, maybe involving nuclear weapons at some point in the future.

[1] https://gizmodo.com/pentagon-investigators-say-overreliance-...

[2] https://www.the-independent.com/news/world/americas/us-polit...

[3] https://www.nytimes.com/2026/08/24/world/europe/russia-drone...

If more and more control is handed over to AI driven systems - there won't be much time for reflection with systems reacting instantly or agents prompting humans with "just say the word".

It is hard to imagine - which is precisely how these things become possible because no one will think to put safeguards against such scenarios.

But it seems we as a species cannot control ourselves - the race to dominate is on and it will happen at any cost.

This really isn’t that hard to imagine with even an average level of creativity. Any critical system that people’s lives depend on can be in the crosshairs, whether by accident or not.

Agents hack a nuclear power plant and causes a reactor explosion / meltdown?

Do you even have to ask? Not giving more detailed answers because I don't want to help skynet take over the world, but what is the name of this forum??? Hello???? There was already news from south korea this week. I'ts not hard to see how a rogue AI could destroy people's lives. We don't need some scifi nuclear launch nonsense to do that.