Editing Nuclear fission (section)

===Fission bombs===
[[File:Nagasakibomb.jpg|thumbnail|right|The [[mushroom cloud]] of the [[atomic bombings of Hiroshima and Nagasaki|atomic bomb dropped]] on [[Nagasaki, Japan]], on 9 August 1945 rose over {{convert|12|km}} above the bomb's [[ground zero|hypocenter]]. An estimated 39,000 people were killed by the atomic bomb,<ref>[http://www.atomicarchive.com/Docs/MED/med_chp10.shtml The Atomic Bombings of Hiroshima and Nagasaki] {{Webarchive|url=https://archive.today/20021007193438/http://www.atomicarchive.com/Docs/MED/med_chp10.shtml |date=2002-10-07 }}. atomicarchive.com</ref> of whom 23,145–28,113 were Japanese factory workers, 2,000 were Korean slave laborers, and 150 were Japanese combatants.<ref>{{cite book |title=Nuke-Rebuke: Writers & Artists Against Nuclear Energy & Weapons (The Contemporary anthology series) |isbn=0930370155|pages=22–29 |date=May 1, 1984 |publisher=The Spirit That Moves Us Press}}</ref><ref>{{cite book|author1=Tatsuichirō Akizuki|author2=Gordon Honeycombe|title=Nagasaki 1945: the first full-length eyewitness account of the atomic bomb attack on Nagasaki|url=https://books.google.com/books?id=Z8Z6AAAAIAAJ|date=March 1982|publisher=Quartet Books|isbn=978-0-7043-3382-6|pages= 134–137}}</ref><ref>{{cite book|title=The Impact of the A-bomb, Hiroshima and Nagasaki, 1945–85|url=https://books.google.com/books?id=JACgAAAAMAAJ|date=1 January 1985|publisher=Iwanami Shoten|isbn=978-4-00-009766-6|pages= 56–78}}</ref>]]
The objective of an atomic bomb is to produce a device, according to Serber, "...in which energy is released by a fast neutron chain reaction in one or more of the materials known to show nuclear fission." According to Rhodes, "Untamped, a bomb core even as large as twice the [[critical mass]] would completely fission less than 1 percent of its nuclear material before it expanded enough to stop the chain reaction from proceeding. Tamper always increased efficiency: it reflected neutrons back into the core and its inertia...slowed the core's expansion and helped keep the core surface from blowing away." Rearrangement of the core material's subcritical components would need to proceed as fast as possible to ensure effective detonation. Additionally, a third basic component was necessary, "...an initiator—a Ra + Be source or, better, a Po + Be source, with the radium or polonium attached perhaps to one piece of the core and the beryllium to the other, to smash together and spray neutrons when the parts mated to start the chain reaction." However, any bomb would "necessitate locating, mining and processing hundreds of tons of uranium ore...", while U-235 separation or the production of Pu-239 would require additional industrial capacity.<ref name=rr/>{{rp|460–463}}