This guide will show you how to complete the Brotherhood of Steel Quest: The Nuclear Option in Fallout 4. This quest involves the conclusion of the main story. If you want to know the end game consequences that come siding Brotherhood of Steel faction, then you’ve come to the right place.
This quest begins immediately after the conclusion of the Brotherhood of Steel Quest: Ad Victoriam. If you would like to know which Brotherhood of Steel quests led up to these events, you can find them on our Fallout 4 Walkthrough and Guide page.
Talk to Elder Maxson
At the end of the Ad Victoriam quest, you will find yourself inside the ruins of C.I.T. after successfully infiltrating through the roof with Elder Maxson and the other Brotherhood soldiers. Speak with Elder Maxson to discuss how you should proceed.
The plan is to target the Institute reactor. Elder Maxson’s orders are to reach the reactor by any means necessary, destroying anything or anyone that gets in the way.
Reach Institute Reactor
Go down the stairs and enter the door to Old Robotics. Be prepared to fight of a ton of Synths and some laser turrets as you enter the chamber. Head through the rooms leading down to a lower level of Old Robotics, eliminating Synths along the way. Go through the east hallway to locate a hatch on the floor.
Open the hatch, then drop down. If you’re quick enough, you should be able to just sprint past the Synths in the room and head straight for the hatch. Continue past the pipes through this lower level, until you reach a door leading to the Bioscience Lab.
Go down the stairs and pass through the doorway on the right leading to the main lab area. Take out the laser turrets along the ceiling, either by using the terminal or by shooting them. Clear the area of hostile Synths, then head through the door leading to the Institute lobby.
Use Terminal to Override Institute Lockdown
- Optional: Issue Evacuation Order
Once you reach the main lobby of the Institute, you’re told that the reactor is located in the Advanced Systems division. However, you must first activate the security override, which can only be done using the Director’s terminal. Ride the center elevator and make your way to Father’s quarters.
As you enter Father’s quarters, you can either hack the computer terminal behind his bed, or speak with him to obtain the override password if you have high enough Charisma. Once you access the terminal, activate the Master Security Lockdown Override. If you want to reduce the amount of Synths you encounter, then use the terminal to issue an evacuation as well.
Reach the Reactor
Exit Father’s quarters and head to the main lobby. Enter the door leading to the Advanced Systems division, taking out any Synths that get in your way. Pass through the lab area, and enter the door to the Institute Reactor. Watch out for the laser turrets as you continue through the long hallway. Reach the upper control room, and head through the door on the left leading down to the reactor.
Plant Fusion Pulse Charge Inside Reactor
The reactor room contains a high level of radiation. Be sure to have some Rad-X and RadAway handy before entering this area. Clear out the enemies, then head up the scaffold to approach the reactor silo. Quickly open the reactor door, and plant the Fusion Pulse Charge on the reactor. Your Rads will rapidly increase once you enter the reactor, so don’t take too long.
Talk to Elder Maxson
Once you have planted the charge on the reactor, speak with Elder Maxson. He will call for Proctor Ingram to teleport both of you to her location in the relay control room.
Talk to Shaun
At the control room, Proctor Ingram informs you of an unexpected person that needs to be dealt with before your group can leave. Speak with Shaun, and decide how you wish to proceed.
Talk to Proctor Ingram
It’s time to head out and watch the sparks fly. Speak with Proctor Ingram, and inform her of your decision regarding Shaun. Afterward, she will teleport everyone out of the Institute to a safe location.
Step Into the Relay
Walk forward into the Relay just west of the control panel. Wait a few moments as Proctor Ingram teleports your crew to the rooftop of the Mass Fusion building.
On the rooftop, you will find the detonator switch upon some metal containers ahead. When you’re ready, push the detonator button to complete the Brotherhood’s mission.
Talk to Elder Maxson
Your work here is done. Speak with Elder Maxson once more regarding the future of the Commonwealth, and the quest will conclude. Completing the Nuclear Option quest brings the main storyline to a close. Nice work, Paladin!