Vault 116 is located in the Columbia Commonwealth about 20 miles from the Capitol wasteland it was the home of Lachlan Hoffmann and many other Vault Dwellers.
Background
The main objective of Vault 116 was testing the affects of Nuka Cola products over many generations this resulted in most of the Vault inhabitants having Nukamania each having a unique version of it. It also may or may not of had a Garden of Eden Creation Kit.
The Meltdown
Since the Vault has been closed for over 200 years the equipment started getting old and rusted and the risks of malfunction was high. The Reactor couldn't take it anymore and went into a meltdown almost all the inhabitants got out safely with only a few not making it. The Reactor exploded causing the vault to become heavily radiated and damaged.
What Lachlan knows about the Vault
Lachlan learned many things about the Vault when he lived in it. He even learned about the Garden of Eden Creation Kit or G.E.C.K he almost learned if Vault 116 had a G.E.C.K but was interrupted by the Overseer coming back into his office.
(WIP)