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I AM BECOME DEATH, THE DESTROYER OF WORLDS.
The Fundamentals of Nuclear Weapon Design
Some Key Facts
The USA is the only nation ever to use a nuclear weapon in combat against a civilian population.....
Twice
In those two events more 100,000 people died in within the blink of an eye.
Another 130,000 died within the month.
August 6, 1945 at 8:15AM
August 6, 1945, 8:15:01
Shadows and Dust
From 1945 to 1991• The US built over 70,000 warheads• In 1991 the inventory was over 23,000
Status of World Nuclear Forces 2009*
Country Strategic Non-Strategic Total Operational Total Inventory Full Report
Russia 2,790 2,050 4,840 13,0001
United States 2,200 500 2,700 9,4002
France 300 n.a. ~300 300
China 180 ? ~180 240
United Kingdom 160 n.a. <160 185
Israel 80 n.a. n.a. 80
Pakistan 60 n.a. n.a. 60
India 60 n.a. n.a. 60
North Korea <10 n.a. n.a. <103 TOTALS 5,850 2,550 8,190 23,335
Current US Population DensityPopulation
305 Million
Cold War Soviet Target Profile
US Population By Time
• 24 Hours Direct Effects ~145 Million
• 1 Week, Fallout & Injuries ~100 Million
• 1 Month, Disease & Starvation < 90 Million
NIKE AJAX AND HERCULESORDNANCE SUPPORT UNITSpecial Weapons Support Shop2800 S. 20th StreetPhiladelphia, Pennsylvania
What Is A Nuclear Weapon?
• Any device that uses fission or fusion to convert mass into vast amounts of energy.
• Such weapons use exotic isotopes of rare materials such as Uranium or Plutonium for fission and/or….
• Tritium and deuterium (or even Lithium) for fusion.
Einstein’s Equation
• E = mc2
• The Hiroshima weapon converted just .025oz of mass to energy and was equal to 1.25 minutes of US electricity production.
• A modern city killer weapon.....• Converts just 1.6oz of mass which is
equal to 70 minutes of electrical production.
Back To Basics
• An atom is made of 3 things.
• The force that holds the nucleus together is immense.
• The Strong Force.
Fission
Chain Reaction
Critical Mass
• Although two to three neutrons are produced for every fission, not all of these neutrons are available for continuing the fission reaction.
• If more neutrons are lost than produced the reaction will proceed very slowly or stop.
Critical Mass
• If the neutrons consumed = the neutrons produced the reaction will self sustain. This is how a commercial reactor works.
• THIS IS CRITICAL MASS• If more neutrons are produced than can be used
the reaction will run away explosively.• THIS IS SUPER CRITICAL MASS.• This is what is needed for a bomb.
Super Critical MassA Matter of Density
• A commercial reactor has tons of U-235.
• It’s spread out over a large volume and
• is mixed with things that keep the reaction going slow…these are called moderators.
• A bomb doesn’t need a lot of mass…
• but it does need to be very dense so the reaction moves quickly.
Size and Shape
• A sphere has the minimum possible surface area for a given mass, and hence minimizes the leakage of neutrons.
• By surrounding the fissionable material with a suitable neutron "reflector", such as beryllium or U-238, the loss of neutrons can be reduced and the critical mass can be reduced.
• By using a neutron reflector, only about 11 pounds (5 kilograms) of nearly pure or weapon's grade Plutonium 239 is needed to achieve critical mass.
Reflective Material
http://www.physics.umd.edu/lecdem/services/demos/demosp4/p4-62.htm
The Guts
• An actual Pu-239 ingot, alloyed with gallium for improved physical properties so it can be formed into a ball.
What Does It Take To Destroy a City?
• A scale model Pu-239 core, or pit, that destroyed the city of Nagasaki in 1945. The entire core assembly was the size of a bowling ball.
• This ball is
crushed to
the size of
Golfball.
Little Boy – Hiroshima~ 15Kt yield 60,000 killed.
• Rapid Assembly.
Fat Man – NagasakiYield 21Kt ~100,000 killed
• Inertial Confinement, aka implosion.
Faster Than A Speeding Bullet
• How to focus the blast on the pit.
• The shockwave moves at 26,700fps
The Added Power of Fusion
The A-Bomb Is Just Match
• A fission bomb, called the primary, produces a flood of radiation including a large number of neutrons.
• This radiation hits the fusion (thermonuclear) portion of the bomb, known as the secondary.
• The secondary consists largely of lithium deuteride. The neutrons react with the lithium in this chemical compound, producing tritium and helium.
The A-Bomb Is Just Match
This reaction produces the tritium on the spot, so there is no need to include tritium gas in the bomb itself unless you want to boost yield on demand.
Just Add One Styrofoam Cooler
• The shock waves produced by the primary (A-bomb) move too slowly to squeeze the fusion stage before the bomb blows itself apart.
• This problem was solved by Edward Teller and Stanislaw Ulam.
• They introduced a high energy gamma ray absorbing material (styrofoam) to capture the energy of the radiation and focus it on the fusion portion.
A Warhead before firing; primary (fission bomb) at top, secondary (fusion fuel) at bottom, all suspended in polystyrene foam.B High-explosive fires in primary, compressing plutonium core into supercriticality and beginning a fission reaction.C Fission primary emits X-rays which reflects along the inside of the casing, irradiating the polystyrene foam.D Polystyrene foam becomes plasma, compressing secondary, and plutonium sparkplug begins to fission.E Compressed and heated, lithium-6 deuteride fuel begins fusion reaction, neutron flux causes tamper to fission. A fireball is starting to form
One Last Bit
• U-238 makes up the casing....• Which when flooded with fusion neutrons then
fissions.• A modern nuclear weapon is thus…• 3 Bombs in one neat package.• The primary is about 10%• The secondary about 60%• The tertiary about 30%.
The Mark-7, 1956
State Of The Art
• A modern H-bomb’s yield can be set prior to use. (We called it dial a bang).
• A modern H-bomb is small!
• Think kitchen trash can.
• A large warhead is just 950 pounds
• With a yield of up to 475Kt
Size Reduction
Left -The 1946 Mk3 with hollow levitated core, Yield 49KT.Right – The ovid core Davy Crocket, Yield 10 – 20 Tons
W80 Warhead
Yield selectable form 5Kt to 170Kt
Strategic Weapons
• Missiles
• Land Based– Minuteman III (500 missiles, 1,500 warheads)
• Submarine Based– Trident D-5 (452 Missiles, 3,616 warheads)
• All Carry the Mk-12A re-entry vehicle
• What is it and how small????
The Navy
• Trident II D-5 SLBM
What You Would See, Maybe
• Each streak of light is = to 10 Hiroshima Bombs.
• There’s 8 in the picture.
• A sub has 24 missiles.
• Do the math.
The Awesome Power• Range 4,500 miles (in <32 minutes)
• 8 warheads, each yield up to 475Kt– Typically around 100Kt.
• Yield is selectable by the crew!
• All 8 warheads will land in a circle just 300’ in diameter.
• Now that’s precision!
• At just $40 million each.
And We Have Robots
Cruising Along
• ALCM AGM-86B.
Off The Line Like Cars
Nuclear Stealth
• The latest AGM-129A Stealth Cruise Missile.
On The Battlefield
• A 120mm (6”) canon shell.
• A nuclear hand grenade?
I’m not making that up.
Way Small
• www.nv.doe.gov/library/films/media/wmv/0800031.wmv
• www.nv.doe.gov/library/films/media/wmv/0800014.wmv
• www.nv.doe.gov/library/films/media/wmv/0800033.wmv
• www.nv.doe.gov/library/films/media/wmv/0800072.wmv
• www.nv.doe.gov/library/films/media/wmv/0800042.wmv
The Horrific Beauty
In 1962, 36 bombs were detonated in the pacific between
April and November.
That’s 1 per week.
And The Nightmare
• http://www.atomicarchive.com/Example/Example1.shtml
• http://meyerweb.com/eric/tools/gmap/hydesim.html
