Reactor Coolant (quest)

Reactor Coolant is a Brotherhood of Steel repeatable quest in Fallout 4.

Detailed walkthrough
This quest becomes available once the main questline of the Brotherhood of Steel has been completed. Proctor Ingram will ask the Sole Survivor to create some reactor coolant. Once reactor coolant has been crafted the player can return it to Proctor Ingram. She will reward the player with 100 caps per unit of reactor coolant.

Once the quest starts reactor coolant becomes available as a craftable item: