"Windows NT 4.0 machine running as late as 2007"

lol. I know a ... factory, that had a BBC model B (with a rather complicated wiring loom) still doing a job around that time.

The IT supplier at the same factory went to a museum in Cambs. around late '90s, early '00s to ask if they could buy an exhibit because something had failed locally. The museum gave them the part.

That was just aerospace and nothing fancy like your nuke plant!