Editing Little Boy (section)

===Radiation===
[[Nuclear fallout|Local fallout]] is dust and ash from a bomb crater, contaminated with radioactive fission products. It falls to earth downwind of the crater and can produce, with radiation alone, a lethal area much larger than that from blast and fire. With an [[air burst]], the fission products rise into the [[stratosphere]], where they dissipate and become part of the global environment. Because Little Boy was an air burst {{convert|1900|ft|m|order=flip|sp=us}} above the ground, there was no bomb crater and no local radioactive fallout.{{sfn|Glasstone|Dolan|1977|page=409 "An air burst, by definition, is one taking place at such a height above the earth that no appreciable quantities of surface material are taken up into the fireball. ... the deposition of early fallout from an air burst will generally not be significant. An air burst, however, may produce some induced radioactive contamination in the general vicinity of ground zero as a result of neutron capture by elements in the soil." p. 36, "at Hiroshima ... injuries due to fallout were completely absent."}}

However, a burst of intense [[neutron radiation|neutron]] and [[gamma radiation]] came directly from the fission of the uranium. Its lethal radius was approximately {{convert|0.8|mi|km|order=flip|sp=us}},{{sfn|Glasstone|Dolan|1977|pages=Chapter VIII and the 'Nuclear Bomb Effects Computer'}}<ref>{{cite web |url=https://nuclearsecrecy.com/nukemap/?&kt=15&lat=34.39468&lng=132.45462&hob_opt=2&hob_psi=5&hob_ft=1968&psi=20,5,1&zm=13 |title=NUKEMAP |last=Wellerstein |first=Alex |website=nuclearsecrecy.com |publisher=[[Alex Wellerstein]] |access-date=2021-07-28}}</ref> covering about half of the firestorm area. An estimated 30% of immediate fatalities were people who received lethal doses of this direct radiation, but died in the firestorm before their radiation injuries would have become apparent. Over 6,000 people survived the blast and fire, but died of radiation injuries.{{sfn|The Atomic Bombings of Hiroshima and Nagasaki, 1946|page=21}} Among injured survivors, 30% had radiation injuries{{sfn|Glasstone|Dolan|1977|pages=545, 546}} from which they recovered, but with a lifelong increase in [[Radiation-induced cancer|cancer]] risk.{{sfn|Richardson RR 2009}}<ref>{{cite news |url=http://www.radionetherlandsarchives.org/50th-anniversary-of-the-a-bomb-attacks-the-ongoing-research-into-the-effects-of-radiation/ |title=The ongoing research into the effects of radiation |newspaper=Radio Netherlands Archives |date=31 July 2005 |access-date=16 December 2018}}</ref> To date, no radiation-related evidence of heritable diseases has been observed among the survivors' children.{{sfn|Genetic Effects}}{{sfn|Izumi BJC 2003}}{{sfn|Izumi IJC 2003}}

After the surrender of Japan was finalized, Manhattan Project scientists began to immediately survey the city of Hiroshima to better understand the damage, and to communicate with Japanese physicians about radiation effects in particular. The collaboration became the [[Atomic Bomb Casualty Commission]] in 1946, a joint U.S.–Japanese project to track radiation injuries among survivors. In 1975 its work was superseded by the [[Radiation Effects Research Foundation]].<ref>{{cite journal |last=Putnam |first=F. W. |title=The Atomic Bomb Casualty Commission in retrospect|journal=Proceedings of the National Academy of Sciences of the United States of America |date=12 May 1998 |volume=95 |issue=10 |pages=5426–5431 |doi=10.1073/pnas.95.10.5426|pmid=9576898 |pmc=33857 |bibcode=1998PNAS...95.5426P |doi-access=free }}</ref>

In 1962, scientists at Los Alamos created a mockup of Little Boy known as "Project Ichiban" in order to answer some of the unanswered questions about the exact [[dosimetry|radiation output]] of the bomb, which would be useful for setting benchmarks for interpreting the relationship between radiation exposure and later health outcomes. But it failed to clear up all the issues. In 1982, Los Alamos created a replica Little Boy from the original drawings and specifications. This was then tested with enriched uranium but in a safe configuration that would not cause a nuclear explosion. A hydraulic lift was used to move the projectile, and experiments were run to assess neutron emission.{{sfn|Coster-Mullen|2012|pp=86–87}}