Vault-Tec Corporate Vault

Vault-Tec's Secret Vault is the company's private Vault, where its members intended to survive the apocalypse and later enter the world having all the useful technologies possible. It was located under the ghoul town of Los. The Vault serves as a major research and production facility and, among its many technological artifacts, housed a special version of Forced Evolutionary Virus.

History
Like many major military contractors, as Vault-Tec grew in finances and responsibility, it began to develop highly experimental and secure technologies. In time, Vault-Tec was so thoroughly integrated with top-secret military research, it was practically a division of the U.S. government … almost. The company still retained some elements of privatization. So the principals of Vault-Tec - executives, scientists, and so on - had to be aware of the true function of the Vaults, and they had access to the technology. They were the developers. Regardless of the U.S. government's directives, Vault-Tec was not going to submit to a lottery and live underground with a bunch of human cattle in facilities that were intentionally defective. Thus Vault-Tec created their own facility, removed from the larger Vault network - and kept secret from the U.S. government. This facility is now known as the Secret Vault.

Vault-Tec didn't stop there. This secret, private installation was used to research the latest technologies that would benefit mankind in a post-nuclear environment. This included some extensive research with a "forced evolution virus" (FEV) which, unlike the government-controlled research at Vault 87, was kept secret from the government. It is known that the FEV in Secret Vault was highly modified to achieve its original goals and avoid sterility, however, unsuccessful.

Other Vault-Tec projects that they intended to use for themselves were their own robotic systems, special biological weapons program (the results are probably a unique race of radroaches and a variation of Deathclaw), medical researches on cell regeneration, and an attempt to create their own Power Armor model.

The robots were implemented successfully and a special AI called CALIX was developed to control the Vault's systems. The Power Armor project resulted in creation of several special armor sets, including Tesla Armor and Power Armor itself, though they were far less protective than T-51b Power Armor or Enclave's variants. The scientists experimented with animals and humans, and probably had a prototype of the government's biological weapon - the Deathclaw, which were affected by their FEV research and heavily mutated.

The inhabitants of the Secret Vault not only lived in safety, but also attempted to study the new world above. There is evidence that they at least captured some Brahmin and used them for both food and experimentation.

Some time after the war, the Secret Vault was torn apart by a local civil war between Vault-Tec scientists and Blake, the chief security officer, who believed the researches with FEV and radiation, conducted on living subjects, including humans, are "evil". Their battles led to a major explosion that devastated a large portion of the Vault and enabled some species of radroaches and Deathclaws, native to the Vault, escape into the wasteland, at the same time allowing radscorpions and rats invade the Vault. CALIX also suffered a malfunction, and lost control over majority of the security robots. The people of the Vault were divided. While many of them now resides in the Garden, other separated groups could be found all around the Vault, including the main residence level, where the majority of people still lived. However, many died due to monster attacks.

After the defeat of the Master, part of his army remained together, under the command of a lieutenant (now a general) named Attis. Highly intelligent and vindictive towards the Brotherhood of Steel, Attis took his group into hiding, searching for clues regarding the history of the FEV virus. Learning about a secret Vault-Tec installation with new and possibly improved versions of the FEV virus, Attis led his group to the area where the rumors started, the ruined city of Los. His ultimate goal, of course, is the continuation of The Master's plan and an attempt to fix the main problem of the super mutants - sterility. Attis take over Vault, but, in the end, it led only to his and his army deaths and the Vault destruction. The majority of human population who survived the mutant attack were able to escape the Vault, however.

The Secret Vault consisted of five main parts: the laboratories, the facilities, the residence area, the garden and the ruins. A nuclear warhead was located underneath the Vault in order to use it to destroy the Vault and all its dangerous researches if the need arises.

The Vault was destroyed when the nuclear warhead was activated by the Initiate. With the Vault, all its researches, all the deathclaw, radroaches, Super Mutants, robots and, more important, heavily mutated Attis, were destroyed. Only a number of Vault inhabitants managed to survive using the auxiliary vent shaft to escape. The Initiate himself used the monorail located in the lab to evacuate quickly to a secret exit in mountains.

Appearances in games
The Secret Vault appears only in Fallout: Brotherhood of Steel.