[gchappel]

[The ones I've been in are constantly "on" and I'm told if they have to shut down it's a $25,000-$30,000 expense and a day to get it back up and running again.[/QUOTE]

I am not sure of the cost to restore these anymore- old fart out of the field.
They used to take a week or more to re-engage. They have to be refilled with liquid nitrogen, then slowly brought back up to power.
They "usually" but not always turn back on.
The quench is quite a catastrophic event with significant stresses to the electromagnetic coils. As they warm they develop resistance and much of the electric power is converted to heat.
In the US, the rooms have to be designed to safely vent the 2000L or so of Liquid nitrogen.
gary