The Nuclear Option Main Story, Brotherhood of Steel Quest

1. Talk to Elder Maxson

Elder Maxson will give you Fusion Pulse Charge.

2. Reach Institute Reactor

We'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.

First, you need to proceed through the old part of the Institute. There is fusion core generator here.

When you get to the central part of the Insitute, the next stage will begin.

3. Use Terminal to Override Institute Lockdown

The only way to reach the Institute's reactor is through a terminal in the Director's quarters.

Terminal is in Father's quarters. Use the main elevator to get there. Unlock it and select Master Security Lockdown Override.

You can also talk to dying Father and you can try to convince him to help you. If you succeed, he will give you access code to turn off some of the synths. To do it, use his terminal and select Director Access: Synth Shutdown.

4. Reach the Reactor

The path to the Institute reactor is now unlocked; I need to pass through the Advanced Systems lab to reach it.

5. Plant Fusion Pulse Charge Inside Reactor

We've arrived at the Institute reactor. Once the Fusion Pulse Charge has been planted, we can finally destroy the Institute once and for all.

6. Talk to Elder Maxson

The charge is in place; we need to get out of the Institute and reach a safe distance before it can be detonated.

7. Talk to Shaun

You can let the boy to go with you or you can leave him in the Institute.

8. Talk to Proctor Ingram

9. Step Into the Relay

10. Activate Detonator

We've successfully made it out of the Institute. All that's left to do now is push the button that will destroy them completely.

11. Talk to Elder Maxson

It's over. The Institute has been destroyed, and the Brotherhood of Steel is victorious.

Next / new quest is A New Dawn (Main Story, Brotherhood of Steel).