Editing Little Boy (section)

==Post-WWII==
[[File: Spare Little Boy atomic bomb casing at the Imperial War Museum in London in November 2015.jpg|thumb|One of five casings built for the Little Boy bomb used on Hiroshima on display at the [[Imperial War Museum]] in London during 2015]]

[[File:Cumulative Shipments of U-235 from Y-12 to Los Alamos 1944-1946.png|thumb|Graph of cumulative shipments of U-235 from the Y-12 electromagnetic enrichment plant at Oak Ridge to Los Alamos, 1944–1946]]

When the war ended, it was not expected that the inefficient Little Boy design would ever again be required, and many plans and diagrams were destroyed. However, by mid-1946 the Hanford Site reactors were suffering badly from the [[Wigner effect]]. Faced with the prospect of no more plutonium for new cores and no more [[polonium]] for the initiators for the cores that had already been produced, the Director of the Manhattan Project, [[Major general (United States)|Major General]] [[Leslie R. Groves]], ordered that some Little Boys be prepared as an interim measure until a solution could be found. No Little Boy assemblies were available, and no comprehensive set of diagrams of the Little Boy could be found, although there were drawings of the various components, and stocks of spare parts.{{sfn|Coster-Mullen|2012|p=85}}{{sfn|Abrahamson|Carew|2002|pp=41–42}}

At [[Sandia Base]], three Army officers, [[Captain (United States O-3)|Captains]] Albert Bethel, Richard Meyer, and Bobbie Griffin attempted to re-create the Little Boy. They were supervised by Harlow W. Russ, an expert on Little Boy who served with [[Project Alberta]] on Tinian, and was now leader of the Z-11 Group of the Los Alamos Laboratory's Z Division at Sandia. Gradually, they managed to locate the correct drawings and parts, and figured out how they went together. Eventually, they built six Little Boy assemblies. Although the casings, barrels, and components were tested, no enriched uranium was supplied for the bombs. By early 1947, the problem caused by the Wigner effect was on its way to solution, and the three officers were reassigned.{{sfn|Coster-Mullen|2012|p=85}}{{sfn|Abrahamson|Carew|2002|pp=41–42}}

The Navy [[Bureau of Ordnance]] began in 1947 to produce 25 "revised" Little Boy mechanical assemblies for use by the nuclear-capable [[Lockheed P2V Neptune]] [[aircraft carrier]] aircraft (which could be launched from, but not land on, the [[Midway-class aircraft carrier|''Midway''-class aircraft carriers]]). Components were produced by the Naval Ordnance Plants in [[Pocatello, Idaho]], and [[Louisville, Kentucky]]. Enough fissionable material was available by 1948 to build ten projectiles and targets, although there were only enough initiators for six. However, no actual fissionable components were produced by the end of 1948, and only two outer casings were available.{{Sfn|Hansen|1995|pp=116–118}} By the end of 1950, only five complete Little Boy assemblies had been built. All were retired by November 1950.{{sfn|Hansen|1995|p=115}}

The [[Smithsonian Institution]] displayed a Little Boy (complete, except for enriched uranium), until 1986. The [[United States Department of Energy|Department of Energy]] took the weapon from the museum to remove its inner components, so the bomb could not be stolen and detonated with fissile material. The government returned the emptied casing to the Smithsonian in 1993. Three other disarmed bombs are on display in the United States; another is at the [[Imperial War Museum]] in London.{{sfn|Samuels|2008}}
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