Shock Value

 is a Fallout 3 quest and achievement that is added to the game in the Broken Steel add-on.

Talk to Paladin Tristan
Right after completing Death From Above you are told to talk to Paladin Tristan in the Citadel. Tristan briefs you on your next mission, which is to retrieve a pre-war experimental device called Tesla Coil from the remains of Olney Powerworks. The scribes need the coil to finish a little surprise for the Enclave, the Tesla Cannon.

(Optional) Use Enclave-controlled Deathclaws to your advantage
If you ask Tristan for a little help, he tells you to talk to Scribe Vallincourt in the Citadel Lab. She gives you a Deathclaw Control Scrambler which allows you to "hijack" Enclave-controlled Deathclaws so long as you are within range of an Enclave transmitter.

South-east of Old Olney is an Enclave camp where you can test the controller. All you have to do is unlock the Deathclaw Cage and let it kill the Enclave soldiers. You can also sneak up the nearby collapsed bridge and get within range of the Deathclaw and watch it attack the Enclave soldiers.

Find the ruins of Olney Powerworks
Once you get to Olney, bring up the local map on your Pip-Boy and look for the entrance to the sewer. Once you get into the sewer, find the ladder which leads to Old Olney Underground. Arriving there, you are greeted by the ghouls Wint and Kidd who are the last survivors of a group of ghouls which tried to establish a settlement here - a plan the Deathclaws apparently did not approve of. The ghouls leave after your conversation, deducing that it's safe to leave the way you came.

From here on, the way to Olney Powerworks is pretty linear. Navigating the Deathclaw-infested Old Olney Underground, you find Wint's and Kidd's dead comrades and eventually reach a door to Old Olney S. Wilson Building. In the building you encounter a couple of Enclave Soldiers and a door on the second level (behind two Enclave Soldiers) that leads to Olney Powerworks.

Find a Tesla Coil
The old power plant is guarded by Sentry Bots which can be deactivated from a couple of security terminals. You can either take the short way by hacking the very hard terminal through the door to your left a bit after you enter or the long way to the right of the fork. Either way, you eventually reach the room with the Tesla Coil which is inside a still-functioning electrical device. Removing the coil results in sustaining a large amount of damage unless you first go down to the room adjacent to the chamber and use the Hard-locked terminal outside the door to the Tesla chamber to shut off the power. Alternately, you can jump into the Tesla Coil chamber from above and activate the three emergency switches inside the chamber. You still receive a small shock, but greatly reduced.

Bring the Tesla Coil to Paladin Tristan
Once done, a nearby ladder takes you out to a street north of Old Olney. Here you are likely greeted by a couple of Deathclaws and upon defeating them you can fast travel back to the Citadel. Hand the coil over to Tristan and receive your next assignment, Who Dares Wins.

Trivia

 * The ghouls Wint and Kidd are possibly named after the henchmen Mr Albert Wint & Mr Charles Kidd from the James Bond film Diamonds Are Forever.

Bugs

 * In some cases, the Deathclaw Cage Key may not unlock the Deathclaw Cage.
 * This editor found that upon entering the Enclave Base, South of Old Olney, even when the Deathclaw was allowed to kill every single Enclave enemy, from max health, the Optional quest was still not completed. Reloading did not fix this problem.
 * I also had the problem of the (Optional) quest not completing. When I arrived at the Enclave camp, the Deathclaw was already free and killing the soldiers.  I did approach from the broken bridge above though, so maybe that's the problem.  Edit: The (Optional) quest completed when I entered the sewer at Old Olney.