The tape can be found in Vault 79, on the desk in the overseer's office.
AC: Just finished offloading before the Big Drop. Even here in the vault we can hear the nukes going off. Command says it should be safe to go top side in six to twelve months. Meanwhile, we'll start shuffling gold bars into the operations shaft. Even if we can go top side shortly, you can bet the former depository is just a slag heap. The gold is probably going to stay here for a long time.