Mini Nuke (Fallout 3)

The Mini Nuke, or micro-nuke, is a small tactical nuclear warhead designed for use in a nuclear catapult weapon $$

Gameplay
Mini Nukes are the most expensive type of ammunition due to their rarity, ranging from 250 to 400 Caps each, depending on the player's Barter skill. They are the ammunition for the two most powerful weapons in the game: the Fat Man and the Experimental MIRV. The explosion when fired is powerful, causing a characteristic mushroom cloud and leaving residual radioactivity. The users themselves may absorb radiation if they are close to the projectile, even after detonation.

Weapons using this ammunition

 * Fat Man
 * Experimental MIRV

Locations
There are a total of 70 Mini Nukes found openly in the world. Two more can be obtained by doing various quests. Another two are in random encounters, one of which only occurs after completing the Reilly's Rangers quest. Another can be found in Operation: Anchorage, 13 in Broken Steel, eight in Point Lookout and two in Mothership Zeta, making for 98 in total with all add-ons.