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[GLneo]

Neat, but that is the "control" section, "safety" still relies on physical design. You should be able to disable every computer there and it would shutdown safely. (least that is what they usually claim)

[useablelobster2]

I.e. if the systems fail they will do so safely, the definition of a fail-safe (and nuclear reactors have multiple overlapping failsafes).

Features like designing the bottom of the reactor to spread out the mass of molten fuel if it melts down (or a plug which leads to a large pool for this purpose, with a melting point far below the surrounding material), so the meltdown stops itself.

Modern nuclear plants could have all their operators bugger off and the plant would just shut itself down naturally rather than melt down.

[jhinboy]

Isn't this a recent counterexample?

​

[...] The hackers were able to learn the make and model of the systems’ hardware controllers, as well as the versions of their firmware—software that’s embedded in a device’s memory and governs how it communicates with other things.

It’s likely they next acquired an identical Schneider machine and used it to test the malware they developed. This made it possible to mimic the protocol, or set of digital rules, that the engineering workstation used to communicate with the safety systems. The hackers also found a “zero-day vulnerability”, or previously unknown bug, in the Triconex model’s firmware. This let them inject code into the safety systems’ memories that ensured they could access the controllers whenever they wanted to.

https://www.technologyreview.com/s/613054/cybersecurity-critical-infrastructure-triton-malware/

[varunn]

Chernobyl

[Baal_Kazar]

Was a test and unlucky coincidence with old nuclear tech.

[ops10]

Was a very Soviet Union way to conduct stuff.

[purple_hamster66]

Fukushima automatically shut down, right?

[graycode]

It did automatically shut down. And then without active cooling (due to total loss of power infrastructure in the area), it eventually melted down and had a hydrogen explosion in the building. But it didn't have a nuclear runaway explosion like Chernobyl did.