Vault 81 Vault 81 is a fallout shelter developed by Vault - Tec , located in the Commonwealth in 2287 . Background . Vault 81 is unlike almost any other known vault in the Commonwealth , in that it still contains sane and active dwellers . The old overseer ' s terminal ( which is stored in the generator room ) makes a heavy implication that this success is not due to them having a more benign experiment to conduct ( like with Vault 101 ) , but rather because the original overseer actively sabotaged Vault - Tec ' s original mandate by refusing to carry out the initial experiments . After a simple quest requiring either three fusion core s or a successful speech check , the Sole Survivor can gain entrance and meet the vault dwellers . Vault - Tec created Vault 81 with the purpose of developing a single , universal cure for every sickness that humanity could possibly suffer from , using the residents as human test subjects . The vault was divided into two separate areas ; the main vault , where up to 96 residents would make their home for the foreseeable future and the secret vault , where Vault - Tec scientists would conduct their research and observe the residents as they were unknowingly exposed to different diseases and cures . The diseases were released via propellant nozzles hidden within the resident ' s rooms . In the case of an evacuation of the vault , all main vault residents were to be incinerated with the same propulsion nozzles . The first vault overseer , Dr . Olivette was skeptical of Vault - Tec ' s goal and possible use of human experimentation . She planned to blow the whistle if it was found to be unethical . However when she received her full briefing she found out the true nature of the experiment she also discovered that Vault - Tec had major backers in the federal government , rendering blowing the whistle as moot . Dr . Olivette was determined to not let the residents of the vault be used as guinea pigs and tried to think of a plan . On the morning of the Great War , Dr . Olivette received the " call " to start the notification of staff and residents , but sabotaged the call list so the science staff wouldn ' t be notified and report in . Her plan mostly worked ; however , three of the science staff turned up . Kenneth Collins and Jim Flint came over with the general population and the third one Burrow , was visiting to ask when the next drill would be . As the three scientists worked to create their cure , Olivette watched over all of their data and personally had to approve the scientists moving onto Phases II and III , animal testing and human testing on unknowing participants respectively . Before human testings could begin , Olivette disabled the delivery systems , cutting off the scientists from infecting the vault dwellers . Additionally , she also sealed all access points to the secret vault , leaving the three scientists to die . To prevent any commotion within the general population , Olivette kept the vault ' s true purpose and the existence of the secret vault , a closely guarded secret . Isolated from the other side of the vault the scientists continued to use animal testing with their last remaining population of mole rats . To help with the research , Dr . Collins modified a Miss Nanny lab assistant to take on greater responsibilities due to the staff shortage , creating Curie . When the scientists eventually died of old age , Curie remained and worked on the cure alone , spending decades conducting trial after trial . She achieved the vault ' s objective in 2204 , perfecting the universal cure . Although Curie had reached a level of self - awareness over the years she was unable to overcome her original programming , which required authorization from a Vault - Tec employee in order for her to leave the vault and begin a new line of research . She patiently idled in the secret vault for decades , awaiting a response from vault security . Meanwhile the residents in the main vault went on with their lives completely unaware that anything was amiss , or that they had been intended as test subjects . In 2277 Overseer Baht opened the vault for the first time , allowing communication and trade with the outside world . Although this provided a badly needed source of food and other vital supplies , especially parts and tools to repair the vault ' s deteriorating systems many residents maintained an isolationist or even xenophobic mindset , distrusting any outsider who was allowed to enter . In 2287 Bobby De Luca , one of Vault 81 ' s dwellers had discovered one of the entrances into the secret vault and used it to store his drugs . Austin Engill witnessed Bobby opening the door and went in to investigate . He was bitten by one of the lab mole rats , which had escaped containment and started a colony in the secret vault decades before . This nest was still infected with the various diseases used in the experiment , resulting in Austin acquiring an unknown lethal disease . When Bobby revealed the existence of the secret vault , the Sole Survivor agreed to search it for a potential cure . Inside , the Sole Survivor discovered Curie who handed over the last unexpired dose of her universal cure . The Sole Survivor could either use it on themself , leaving Austin to perish and earning the animosity of the vault dwellers , or turn it over to save Austin and be granted a room in the vault by Overseer McNamara and appreciation throughout the vault . Layout . Vault 81 is divided into two main areas : the regular vault , where the residents live , and the secret observation area , where the scientific team used to observe the vault dwellers and conduct research . By 2287 , the secret area is overrun by a special breed of mole rats while the regular vault is still functional and inhabited by vault dwellers . There are two entrances from the main vault to the secret vault : an elevator located in the lobby , and a secret door in the reactor room . Although the elevator cannot be used until the end of the quest Hole in the Wall and the secret door is not unlocked before the beginning of the same quest . Appearances . Vault 81 appears only in " Fallout 4 " .