Mini nuke (Fallout 3)

The mini nuke or micro-nuke is a football-sized tactical nuclear warhead designed for use in a nuclear catapult weapon in Fallout 3.

Characteristics
Mini nukes are the most expensive type of ammunition, ranging from 250 to 400 caps a piece to buy, depending on your Barter skill. They are the ammunition for the two most powerful weapons in the game: the Fat Man and the experimental MIRV, doing many times more damage than any other weapon even at low Big Guns skills. Despite having nuclear qualities, outside influences besides firing it from the Fat Man will not cause it to detonate.

Weapons using this ammunition

 * Fat Man
 * Experimental MIRV

Locations
There are a total of 70 free mini nukes in Fallout 3. Two more can be obtained by doing various quests. Another two are in random encounters, one of which only occurs after you complete Reilly's Rangers. Another one can be found in Operation: Anchorage, 13 in Broken Steel, 8 in Point Lookout and two in Mothership Zeta, making for 98 in total with all add-ons.

Available infinitely

 * One way of obtaining mini nukes is to kill super mutant overlords which are found throughout the Capital Wasteland. Super mutant overlords can only be found with Broken Steel installed.
 * Flak 'N Shrapnel's in Rivet City frequently restock with mini nukes, to the extent that one can acquire up to five of them with every visit.