Dr. Kelstrup's Office, accessible through the Atirum, contains a safe with a randomly generated code. This means it is different for everyone in every Prey playthrough. However, where to find this safe code is the same every time.
The code for Dr. Kelstrup's safe will be given to you by Alex in the Atrium, and he'll send you on a mission to his office to retrieve certain Neuromods.
Prey (2017) Dr. Kelstrup's Safe Code - GameRevolutionWATCH GALLERY