question: Where were the explosive components of the weapon that detonated on Nagasaki, Japan on 8/9/145 made? 
answer: The Salt Wells Pilot Plant
context: Title: Fat Man
  Passage: "Fat Man" was the codename for the atomic bomb that was detonated over the Japanese city of Nagasaki by the United States on 9 August 1945.  It was the second of the only two nuclear weapons ever used in warfare, the first being Little Boy, and its detonation marked the third-ever man-made nuclear explosion in history.  It was built by scientists and engineers at Los Alamos Laboratory using plutonium from the Hanford Site and dropped from the Boeing B-29 Superfortress "Bockscar".  For the Fat Man mission, "Bockscar" was piloted by Major Charles W. Sweeney.
  Title: Gravel Gertie
  Passage: A Gravel Gertie is a type of bunker designed to provide containment during the nuclear weapons assembly process, when the plutonium or highly enriched uranium "pit" is mated with the high explosive components and wired into the electronics (the "physics package") of the warhead.
  Title: Salt Wells Pilot Plant
  Passage: The Salt Wells Pilot Plant was a facility established by the Manhattan Project at the Naval Ordnance Test Station (NOTS) at Inyokern, California, where non-nuclear explosive components of nuclear weapons were manufactured.  The first explosives were melted, mixed and poured on 25 July 1945.  Between 1945 and 1954, it manufactured explosive components of the Fat Man, Mark 4, Mark 5 and Mark 12 nuclear bombs.  The Salt Wells Pilot Plant also helped design, equip, and train workers for the Burlington AEC Plant in Iowa and the Pantex Plant in Texas.  The Salt Wells Pilot Plant closed on 30 June 1954.
citations: Salt Wells Pilot Plant Fat Man