The mutant prison featured in Deadpool 2 is called the Icebox.
In the film, the Icebox is a heavily guarded facility where mutant inmates are held. Wade Wilson is sent there after an intervention involving the young mutant Russell Collins, whose future identity is Firefist. Cable later travels back in time to target Russell before he becomes a killer.
The Icebox is not the same as Alkali Lake, a military and research location associated with Wolverine in earlier X-Men films. It is also unrelated to Cerebro, the machine used by Professor X to locate or communicate with mutants.
Deadpool 2 was released in 2018 and was directed by David Leitch. The prison sequence brings Deadpool, Russell and Cable together and leads directly to the film’s major action set pieces.