The Nuclear Option (Brotherhood of Steel)

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

Quick walkthrough
Talk to Elder Maxson and use the terminal to override the Institute lockdown. Reach the reactor and plant the fusion pulse charge. Report back to Maxson, then step into the relay and activate the detonator.

Bugs
After blowing up the Institute you may find yourself unable to talk to Elder Maxson to continue the quest, or he may be absent. For the PC, open the console and use commands, and then  to teleport Elder Maxson to the you.