W. Udo Schröder, 2004 Nuclear Weapons 1

W. Udo Schröder, 2004 Nuclear Weapons 2 Acknowledgements/Disclaimer All information in this presentation is in the public domain This information is insufficient to actually build a nuclear device Historical material, including video clips, has been taken mainly from US government websites, atomic weapons archive Guide to nuclear weapons, Federation of American Scientists, Membrane domain (garwain.membrane.com/hew) Some animations are taken from the website “HowStuffWorks”

W. Udo Schröder, 2004 Nuclear Weapons 3 Physical Foundation of Nuclear Fission Weapons Fission based “atomic” bombs Task: Initially stable, sub-critical configuration of fissile material produce prompt criticality, a self-sustained super-critical fission chain reaction with fast neutrons, produce exponential n multiplication  explosion explosive disassembly in short time, internal expansion+surface blow-off decreases density prevent premature rediation of energy to outside  tamper, using most of material  use U or Pu metal Typical conversion in a weapon: 1 kg U/Pu  17 kT TNT + 5·10 24 n

W. Udo Schröder, 2004 Nuclear Weapons 4 Critical Masses Critical Masses for Plutonium Compositions Total mass Pu (kg)/ 239 Pu (kg), density = Isotopic Composition Reflector. atomic % None 10 cm nat. U % 0% 10.5/ /4.4 90% 10% 11.5/ /4.3 80% 20% 12.6/ /4.3 70% 30% 13.9/ /4.3 60% 40% 15.4/ /4.2 50% 50% 17.2/ /4.0 40% 60% 20.0/ /3.7 20% 80% 28.4/ /2.6 0% 100% 40. / /0.0. Pu kg Pu kg Pu kg Pu kg Pu kg Am kg All Pu mixture have critical masses  all produce nuclear explosion, if supercriticality is reached fast enough  geometry, reflectors, tampers

W. Udo Schröder, 2004 Nuclear Weapons 5 Effect of Reflector

W. Udo Schröder, 2004 Nuclear Weapons 6 The US Manhattan Project 1941: Rudolph Frisch & Otto Peierls (in UK) calculate critical mass 235 U (~10 lbs) Dec. 1942: Fermi’s reactor in Chicago went critical April 1943: Site Y: Los Alamos/NM laboratory Industrial Scale Test Experiments Pu prod U enrichmt ORNL K-35 Plant

W. Udo Schröder, 2004 Nuclear Weapons 7 Atomic-Bomb Gun Design “fool proof” design, had not been tested before deployment

W. Udo Schröder, 2004 Nuclear Weapons 8 Trinity Site Atomic Bomb Tests July 16, 1945 First explosion of a nuclear device. North of Alamogordo/NM

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W. Udo Schröder, 2004 Nuclear Weapons 10 The Hiroshima Bomb 60 kg U 0.8 kg used in fission (=1.3%) rest dispersed into atmosphere

W. Udo Schröder, 2004 Nuclear Weapons 11 Pu Nuclear Fission Bomb Deployed in Nagasaki, 1945 ignition by n from Pu  Be internal initiator 6 kg Pu  22kt (fission of 1.3 kg Pu) more efficient:  = 20%

W. Udo Schröder, 2004 Nuclear Weapons 12 The Nagasaki Bomb Designed and built in Los Alamos

W. Udo Schröder, 2004 Nuclear Weapons 13 “LittleBoy” and “Fat Man” in Los Alamos Museum

W. Udo Schröder, 2004 Nuclear Weapons 14 Hiroshima, August 6, 1945

W. Udo Schröder, 2004 Nuclear Weapons 15 Memorable Events August 6, 1945 Hiroshima: “Little Boy” fission bomb (gun design, 60 kg 239 U, 14.5 kt TNT) dropped by Enola Gay B-29 bomber August 9, 1945 Nagasaki “Fat Man” (implosion design), 6.2 kg 239 Pu  22 kt TNT November 1, 1952, Eniwetok Atoll: “Mike” 10Mt thermo-nuclear (hydrogen) bomb (radiation implosion), 1961, Soviet Union: 60 MT hydrogen bomb Fat Man Mike

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W. Udo Schröder, 2004 Nuclear Weapons 17 Physical Foundations of Thermonuclear Bombs Fission bomb as ignition of hydrogen device Fusion based “thermo- nuclear” bombs t-”breeding” reactions t 1/2 = a

W. Udo Schröder, 2004 Nuclear Weapons 18 Boosted Thermonuclear Bombs X-ray radiation transfers energy to fusion chamber fission n render rod super-critical n+ 6 Li  4 He+t  ignites d-d, d-t fusion Staged radiation implosion Teller-Ulam design (1951): chemical explosive implodes kg-Pu charge exploding Pu produces many (80%) soft X rays transferring energy fast (10-8 s) to secondary Li/D fusion charge  s dd, dt reactions Edward Teller

W. Udo Schröder, 2004 Nuclear Weapons 19 2-Stage Radiation-Implosion Bomb

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W. Udo Schröder, 2004 Nuclear Weapons 21 Effects of Nuclear Weapons Radiation, direct and delayed (fall-out), soil contamination Thermal Blast effects, direct dame, material in atmosphere Electromagnetic pulse EMP effects

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