My understanding is that the Therac-25 UI was essentially a CAD program that allowed the operator to design treatment programs.
The software failed to prevent the operator from entering invalid treatment programs which then killed patients.
I seem to remember that this was made worse by operators using a shortcut from a previous version which was safe because of some additional hardware, but the hardware lock was removed in the 25, and it killed people.
Clever comment! But wait, is that really the Therac-25 you're thinking of? The Therac-25 was basically just a bug-trap of assembly language race conditions, that's all.
There was another similar case of a radiation machine in which the dose was supposed to take into account the shield. The user could draw the shield with a CAD-like plannning program. The users tried to draw a shield with a cutout, and the CAD display led them to believe that the shapes were being subtracted. (The filled path was drawn with the in-out rule or whatever.) The actual dose calculation though ignored this and added the negative area as a positive. Whoa, you have lots of shielding, crank up the radiation! Or something like that.
This is not actually the radiation machine but the treatment "planning" software. (It meets the definition of CAD: it's computer software, and it's assisting in the design of something: the treatment.)
Gee what was this? Perhaps that circa 2000 incident in Panama?
You are seriously scaring the shit out of me. I'd be more scared, only my Uncle was in charge of a standards body in a certain nuclear research organisation several decades ago and a few of his old war stories would make your hair turn white.
Thankfully when I did work for that same organisation they had completely changed their culture, and things were considerably better, but still I suspect that if you explore the bush around the facility (which I doubt the police would allow...) you might see some unusual things.
The software failed to prevent the operator from entering invalid treatment programs which then killed patients.
I seem to remember that this was made worse by operators using a shortcut from a previous version which was safe because of some additional hardware, but the hardware lock was removed in the 25, and it killed people.
https://en.wikipedia.org/wiki/Therac-25