Vaults

A Vault is a type of subterranean installation designed by Vault-Tec. Officially, they were designed for the sole purpose of sheltering up to one thousand dwellers from a nuclear holocaust. But in reality, they were used as a secret experiment for the government.
Background
Commissioned by the United States government as part of "Project Safehouse", Vault-Tec built 122[1] vaults across the country. However, when the storm of nuclear war came in 2077, the vaults were sealed without many of their dwellers due to the "Cry Wolf" effect training drills had on the populace.
The first vault was built in Los Angeles, intended to demonstrate the viability of such a facility. The demonstration vault was built beneath the city, within its limits. Unlike other vaults, it wasn't part of the experiment. Most vaults were completed by 2063, except for Vault 13 and Vault 112. Vault 112 was the last Vault to be completed, in June of 2074.
Overview
The vaults were one of the most expensive shelters in the pre-War world. According to the Vault Dweller's Survival Guide for Vault 13 (otherwise known as the Fallout manual), the intended budget for that particular installation was $400 billion dollars, and by the end of its construction reached $645 billion (although it should be mentioned that prices in the Fallout setting are highly inflated; there are advertisements for vehicles in Fallout 3 loading screen slides for "'Only' $1,000,000,"). The vaults were located in various locations, and little information is available as to why those particular sites were chosen.
Each vault was designed to hold one thousand occupants at any given time, although hot-bunking was required at maximum capacity, and equipped with all facilities and supplies needed by them to survive in isolation for the designated time. According to the Vault 101 PA System, the life support system could work for over 900 years without failure. The facilities and supplies for Vault 13 included complete construction equipment, hydro-agricultural farms, a water purification system, defensive weaponry to equip 10 men, communication systems and surface monitors, social, and entertainment files (for total duration). Waste management was conducted by burning trash on scheduled "burning days". Larger incinerator receptacles were used for the destruction of human corpses. In addition, some vaults received one or two G.E.C.K.s, intended to help the inhabitants create a viable civilization in the post-nuclear world after the All Clear signal is sent.
Different types of power sources were utilized for the vaults. Vault 13 relied primarily on geothermal energy, with backup power available from a General Atomics nuclear power generator, enough to sustain the vault for two hundred years. Vault 8 on the other hand, relied on an inefficient nuclear reactor,[2] which, while enough for Vault City to emerge, could only support a relatively small, highly advanced settlement, and in 2241 was nearing its capacity, after which further growth would be impossible.
All vault dwellers wear blue-and-yellow jumpsuits, although the design varied between different vaults. The typical vault dweller living in a properly maintained vault could expect to live an average of 92.3 years.[3]
Needless to say, most vaults in the experiment failed and had results completely different than those advertised. Many who exited successful vaults seem to suffer from xenophobia (fear of strangers) and/or agoraphobia (fear of open places); notable examples would be Michael Angelo, who doesn't dare leave the Strip even for inspiration, the Boomers who shoot artillery at anything that comes close to them, and the Vault 101 citizens, who still don't exit the vault even after the Lone Wanderer opens its door. Notable exceptions would be the Vault Dweller, the Lone Wanderer, Butch DeLoria, and Doc Mitchell.
Layout
The vaults are all very similar in their basic functions, but sometimes were constructed according to different designs. The vaults of the West Coast differ from those constructed in the vicinity of Washington, DC and the Mojave area.
It should be noted that due to scaling, the size of vaults in games shouldn't be taken at face value. None of the explorable vaults in the games have enough space or facilities to actually house 1000 people (or rather 500, as hot-bunking is used at maximum capacity). However, many doors within in-game vaults are inaccessible, which allows for the possibility that the vault is far larger than the areas the player can access.

Entrance

The entrance houses the Vault's only connection to the outside world - the airlock (with the exception of Vault 19 and Vault 87). A Vault computer It is closed from the inside by a reinforced high-security door and from the outside by a massive, gear-shaped, four-foot thick vault door, which Three Dog claims "weighs, like, thirteen tons". For most vaults this the only means of entering or leaving. (Only Vault 87 and Vault 19 had any other entrances.) Most vaults have consoles located on both the inside and outside, either of which requires a security code to open the outer door. These codes are usually only known to a handful of people within the facility so as to prevent unauthorized exits.
The automated narrator in Washington DC's Museum of Technology states that the vault doors had a projected 2% failure rate in case of a direct hit by a nuclear missile. The only known vault to have been hit by a nuclear weapon is Vault 87, and according to the logs of its overseer, that blast damaged the door beyond repair. This could have been merely a "lucky shot" falling within the 2% failure, but it seems more likely that Vault-Tec's strength projections were incorrect or exaggerated.
Vault 15 townmap Most vaults use a Seal-N-Safe Vault Door Model No. 343[4] to secure the airlock. Some older vaults (such as Vault 101) use a different, cruder blast door model. Vault 8, the control vault, had also a second, much larger, blast door built, securing the entry hallway leading to the entrance to the vault.
The entrance level also houses the Emergency Medical Lab complete with an Auto-Doc. A vault medic was required to be present at the EML 24 hours a day. The lab had the equipment to treat nearly all injuries and illnesses, ranging from simple bruises to irradiation.

Living Quarters

Standard pre-War design of the living quarters was that of a single room with a sanitary annex. Vault 13 had one hundred living quarters, and at maximum capacity, ten people would be assigned to a single living quarter, in a hot- bunking system. A standard level had 20,000 square feet of usable area.
The lights in the vaults used Simu-Sun technology, making it feel just like the outdoors, with only a fraction of a sunburn risk. The lights in Vault 101 were kept on all the time to prevent a radroach infestation.
New Entertainertrons were used to play holotapes, and used as a slide projector in the classroom of Vault 101.

Command Center

Vault 13 Overseer Command Post A Secret Vault Command Post Heart of the vault, the command center was where the overseer's seat was located. The operations center, apart from the seat of power, included the computer lab, where the water purification system was located, and an armory, where the vault's weapons, ammunitions and armor were stockpiled. A security guard was posted in the command center at all times, to ensure that the armaments were properly secured and handed out only to people possessing the proper clearance from the overseer.
Apart from that, the level also contained the computer core (with the vault's AI monitoring the shelter 24/7), housing data processing units, a library playing an important role in educating vault dwellers, a common meeting room, and the primary store room, where the most important supplies would be stored.
The overseer is also able to see anyone inside the vault with the Eye-on-You cameras.
Equipped with dual 5mm miniguns in some vaults, the overseer's command post can be considered the last line of defense in case vault security is breached.
In the Secret Vault, there are several command posts for the various sections. The command posts mainly contain buttons to control things like locking of doors and laser protection.

Differences

• Vault 29 (Van Buren) was outfitted with a ZAX AI, which replaced the Overseer.
• Vault 12 had its Overseer's room sealed due to the fact that the main door of the vault was doomed never to close.
• East Coast vaults and Mojave vaults (3, 11, 19, 21, 22, 34, 87, 92, 101, 106, 108, 112) use a different, older door mechanism (as evidenced by extensive rusting and meager safety precautions). These vaults employ an opening mechanism that is contained entirely within the vault itself, pulling the door inwards and simply rolling it to one side. The doors seen on West Coast vaults, however, pull the seal outwards and use an external clamp to slide it aside.
• East Coast and Mojave vaults lack storage rooms in the overseer's office; they are instead located near the Atrium.
• Vault 0 and the Secret Vault had an entirely different layout than other vaults.