A Model Citizen

A Model Citizen is a quest in the Fallout 4 add-on Vault-Tec Workshop.

Detailed walkthrough
After reaching Valery Barstow, she will ask you to follow her as she explains her situation. There are several feral ghouls nearby who used to be the construction team working inside the Vault. The nearest one, Julian, will become hostile if you get too close to him. Barstow will ask him to stop, before realizing he no longer responds, and will request that you put the rest of the construction team out of their misery. Once all the ghouls are dead, Barstow will explain that Stanislaus Braun tasked her with a vital experiment for Vault 88.

If you choose the 'Vault-Tec are bastards' option, she will understand, and put you in charge of the experiment to change its ethical parameters as you see fit. (May need verification further in the questline). You also have an option to expel Barstow from the vault, permanently failing and ending the questline, but giving you control of the entire vault and granting access to all of the prototypes. The achievement Oversight may also be gained here.

If you agree to her wishes, you must then build the Overseer's Desk with the workshop for her. Once she has consulted the terminal, she will ask you to turn on the radio beacon in the entranceway where Andersen was encountered. Its switch is on the large control board in the middle of the room. After that is completed, you will be told to explore the rest of the vault, triggering a sidequest. This requires clearing rockfalls that have blocked up entrances to passages beyond the main chamber.

Once enough of the vault has been explored (not all sectors are required for this to happen) the next stage is to help Barstow interview new candidates into the vault. A group of Settlers will have appeared at the entrance to the Vault, summoned by the radio beacon.