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Press that button and you not only defeat our enemy, you restore order and decency to the Commonwealth. It's time, Paladin. The Institute and their synth abominations must be eradicated.Arthur Maxson

The Nuclear Option is the final Brotherhood of Steel main quest and an achievement/trophy in Fallout 4.

Quick walkthrough

Brotherhood of Steel main quest: The Nuclear Option
Speak with Elder Maxson.
Go to Father's quarters.
(Optional) Speak to Father.
(Optional) Issue evacuation order.
(Optional) Activate synth deactivation code.
Use terminal to override Institute lockdown.
Reach the reactor.
Plant fusion pulse charge inside reactor.
Talk to Elder Maxson.
Get to the Relay.
Talk to Proctor Ingram.
Take Shaun with you.
Leave Shaun behind.
Step into the Relay.
Activate the detonator.
Talk to Elder Maxson.
Reward: 1500+ XP
Leads to: A New Dawn

Detailed walkthrough

After dropping into the hole made by Liberty Prime (completing Ad Victoriam), the Brotherhood insertion team will find itself around the corner from the teleportation room where the Sole Survivor first entered the Institute. Elder Maxson will hand out an explosive charge to place on the Institute reactor. Proctor Ingram stays behind to get the teleporter working, and the rest of the team proceeds forward.

The Sole Survivor must go through the old Robotics wing, now a ruined section of the Institute, eventually coming out in Bioscience. If the Sole Survivor has not retrieved the experimental serum for Virgil yet, they should do so now as it will be their last chance.

Once in the main section of the Institute, they must clear it of enemies. Once done, they must go to speak to Father. Father can be persuaded with a Speech check to reveal the password to disable a part of the synths that protect the Institute. Once finished, they can do as they wish with Father, and issue the evacuation order if they wish to. Afterwards, they must enter Advanced Systems, then clear the section of enemies, and get to the reactor. After doing so, they must activate the terminal, activate the radiation sweep, and then disable the reactor's shielding. Then, they must plant the explosive. They will then be teleported out of the reactor section. Ingram will explain that Shaun, the synth child, showed up. The Sole Survivor must decide what to do with Shaun, and must then step into the molecular relay.

Afterwards, Maxson will tell them that the honor should be theirs to activate the explosive. After doing so, Maxson will tell them to return to the Prydwen and the quest will be completed.

Quest stages

Quest stages
StageStatusDescriptionLog Entry
300 Talk to Elder Maxson
400 Reach Institute ReactorWe've entered the Institute. I need to reach the reactor and place a Fusion Pulse Charge on it so we can destroy the entire facility remotely.
430 Use Terminal to Override Institute LockdownThe only way to reach the Institute's reactor is through a terminal in the Director's quarters.
450 (Optional) Issue Evacuation Order
475 Reach the Reactor
500 Plant Fusion Pulse Charge Inside ReactorWe've arrived at the Institute reactor. Once the Fusion Pulse Charge has been planted, we can finally destroy the Institute once and for all.
600 Talk to Elder MaxsonThe charge is in place; we need to get out of the Institute and reach a safe distance before it can be detonated.
700 Talk to Proctor Ingram
710 Talk to Shaun
740 Step into the relay
800 Activate detonatorWe've successfully made it out of the Institute. All that's left to do now is push the button that will destroy them completely.
900 Talk to Elder MaxsonIt's over. The Institute has been destroyed, and the Brotherhood of Steel is victorious.
1000Quest finishedQuest complete


  • If Paladin Brandis was convinced to rejoin the Brotherhood ranks after the Lost Patrol, he will be part of the forces entering the Institute. Be warned, he can die during this mission.
  • With 10 Intelligence and Idiot Savant rank 2 triggering, this quest can yield a staggering 9750 XP upon completion.
  • After this quest has been completed several synth soldiers (along with a suit of power armor) will occasionally appear floating above the now cratered remains of the C.I.T. ruins. They are not hostile unless shot and even then don't pose much of a threat since they are swimming.
    • The armor can be retrieved, without the use of console commands, by exploiting the physics glitch related to engine blocks. Though difficult, one can position themselves over the armor, let go of the block, and get in, thus depositing the player and power armor in the water below. Due to the rarity of engine block models in the world, and the considerable distance they must be carried to the Institute crater, this method is a considerable undertaking.
  • Shortly after the explosion, the ending cutscene will start.


  • PCPC After blowing up the Institute one may find themselves unable to talk to Elder Maxson to continue the quest, or he may be absent. For the PC, open the console and use commands prid 1cc18, recycleactor and then moveto player to teleport Elder Maxson to the player's location. [verified]
    • One may not need to use recycleactor, just prid & moveto.
  • PCPC Playstation 4Playstation 4 Entering and exiting the FEV lab may cause several synths to become allied to the Brotherhood and attack other synths. [verified]
  • PCPC Quest may become stuck on "Speak with Shaun" with no way to move forward without using the console. [verified]
    • SetStage MQ302BOS 720 (taking Shaun) or SetStage MQ302BOS 730 (leaving Shaun) will fix this issue.

See also