Origins Operation Sandstone

enewetak atoll

nuclear weapons developed during world war ii manhattan project, created network of production facilities, , weapons research , design laboratory @ los alamos national laboratory. 2 types of bombs developed: mark 1 little boy, gun-type fission weapon using uranium-235, , mark 3 fat man, implosion-type nuclear weapon using plutonium.

these weapons not far removed laboratory origins. great deal of work remained improve ease of assembly, safety, reliability , storage before ready production. there many improvements performance had been suggested or recommended during war had not been possible under pressure of wartime development. norris bradbury, replaced robert oppenheimer director @ los alamos, felt had, put bluntly, lousy bombs.

plutonium produced irradiating uranium-238 in 3 250 mw nuclear reactors @ hanford site. in theory produce 0.91 grams (0.032 oz) of plutonium per megawatt-day, or 20 kilograms (44 lb) per month. in practice, production never approached such level in 1945, when between 4 , 6 kilograms (8.8 , 13.2 lb) produced per month. fat man core required 6.2 kilograms (14 lb) of plutonium, of 21% fissioned. plutonium production fell off during 1946 due swelling of reactors graphite neutron moderators. known wigner effect, after discoverer, manhattan project scientist eugene wigner.

these reactors required production (by irradiation of bismuth-209) of polonium-210, used in initiators, critical component of nuclear weapons. 62 kilograms (137 lb) of bismuth-209 had irradiated 100 days produce 600 curies of polonium-210, little on 132 milligrams (2.04 gr). because polonium-210 has half-life of 138 days, @ least 1 reactor had kept running. oldest unit, b pile, therefore closed down available in future. investigation of problem take of 1946 before fix found.

uranium-235 derived enrichment of natural uranium @ y-12 plant , k-25 site in oak ridge, tennessee. improvements in processes , procedures of electromagnetic , gaseous isotope separation between october 1945 , june 1946 led increase in production around 69 kilograms (152 lb) of uranium-235 per month, enough 1 of wasteful little boys. fat man 17.5 times efficient little boy, ton of uranium ore yield 8 times uranium-235 plutonium, , on per-gram basis, plutonium cost somewhere between 4 , 8 times produce uranium-235, @ time cost around $26 per gram.