Stop officer Jack from blowing up the power plant is a quest in Fallout 2.
The capital of the NCR relies on its power plant to supply electricity to street lights, forcefields, computers, and other amenities throughout the city. As the police assumed no one would try to destroy it, it was left unguarded. This backfired when Jack, an NCR police officer, snapped following a divorce with Mira, strapped himself with explosives, and threatened to blow up the power plant. The player can resolve the situation at the request of Dorothy, the city engineer.
Speaker or Speech 80% will allow the player to talk Jack down. The player has to antagonize Jack and coerce him to spill his guts, rather than try to appease him as it will backfire. The easiest dialogue path is 1,2,1,2,1,2,1,2.
Successfully talking him down will give a sizable bonus (6000 XP) on top of the 3000 XP and skill books received from Dorothy.
Otherwise, the player will have to gun Jack down. They have to wait for Jack to begin his routine ("Bite me! This is Jack!"), otherwise an attack will register as a hostile action and turn the entire town hostile.
Dorothy will grant 3000 XP and gift the player skill books, but only if the player answers there was no other way to avoid bloodshed.
The player can let Jack blow himself up, then repair the power plant (by targeting the bank of monitors next to Jack's remains) with Science or Repair. Note that while the player can only tell Dorothy they're good at fixing things with at least 65% in Repair, repairs can be attempted regardless of skill level.
This method grants the usual 3000 XP and the skill books, plus Jack's worldly possessions.
The player can always allow Dorothy to try to repair the computer and fail miserably. Doing so gives no other reward than a Scout Handbook and Dean's Electronics found on her body. While the forcefields in the city go down, guards will not appreciate trespassing.