This definition appears very rarely
and is found in the following Acronym Finder categories:
Samples in periodicals archive:
3142, transient personnel unit (tpu) barracks at naval base, san diego, ca
This second message, (221323Z JUL 11, SUBJ/MISHAP REPORTING RESPONSIBILITIES FOR PERSONNEL ASSIGNED TO /MEDHOLD OR TPU//) is a message that specifies who is responsible for reporting injuries for personnel assigned to a medical hold unit (MEDHOLD) or to a transient personnel unit (TPU).
At one point I asked a young Sailor why he ended up on limited duty and was being assigned to the transient personnel unit.