It's a good job we've got EASA and all that money being spent on SESAR in Europe (read this as NextGen if you're in the New World) because all the controllers who know anything about stopping aeroplanes from banging into each other while they've got their eyes shut will be retired soon!
........in around 22 years.........
The likelihood of any ATC system failing for any prolonged amount of time due to radar failure is so remote that teaching procedural just isn't worth the money. Just because a system fails it doesn't mean the radar goes.