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Nuclear fission Our course review

Nuclear fusion

Lasers: NIF/LLNL Nuclear weapons • We have two lectures after today: next Tuesday and Thursday. 235 U • I promise to return graded papers, homework, and exams next 239 Pu Tuesday, March 5 (I am finally at home with no work travel this and weekend). Fusion weapons • Reading period begins Tuesday, March 12; exam on Tuesday, Example nuclear weapons March 19 at 7 pm. Exam will be open laptop or tablet, where you email to me your exam answers; otherwise, similar style to midterm exam. If you do not have a laptop or tablet, email me. • Writing assignment due March 11: a briefing paper to the President of the USA on a topic where some physics knowledge is required (see next slide). You are encouraged to email me about your proposed topic; I can give you a few suggestions and ideas. Nuclear fission Final paper due March 11 review

Nuclear fusion

Lasers: NIF/LLNL Nuclear weapons 8–12 page briefing paper, double-spaced, with citations. Submit through Manhattan Project 235 U SafeAssign. 239 Pu Trinity • Abstract (roughly half a page, summarizing your paper; use italic Hiroshima and Nagasaki font) Fusion weapons • Statement of problem Example nuclear weapons • Relevant information (the quality of the sources you use will be part of your grade) • Proposed action, including discussion of costs and benefits • Arguments against your proposed action, and your counter-arguments • Conclusion Nuclear fission Curve of binding energy review Here’s the curve of binding energy shown inverted, so that nuclei like to Nuclear fusion roll up the hill. Notice the “bumps” near magic numbers Lasers: NIF/LLNL 2 · [2, 8, 20, 28, 50, 82, 126]; these are analogous to closed electron shells Nuclear weapons

Manhattan Project with atoms (i.e., noble gases). 235 U 239 Pu Trinity Hiroshima and Nagasaki

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This figure from Georgia State’s Hyperphysics web site Nuclear fission Nuclear fission review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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(Wikipedia) Nuclear fission Nuclear waste disposal review • Nuclear waste is hot and Nuclear fusion nasty stuff (the scale at Lasers: NIF/LLNL left tops off at 104 TBq, Nuclear weapons or 104 · 1012 = 1016 Manhattan Project 235 U decays/sec). However, it’s 239 Pu Trinity compact and contained. Hiroshima and 137 Nagasaki Note how Cs with a

Fusion weapons half life of 30 years Example nuclear dominates the activity at weapons first. • U.S. does not yet have an agreed-upon, operating permanent repository for high level waste. There are both technical questions (how do you guarantee containment for millions of years?) and political ones. Nuclear fission Passive reactors review Nuclear fusion Most reactors now in operation are based on 40 year old designs. New Lasers: NIF/LLNL designs feature passive (convective) cooling, and built-in backup water Nuclear weapons reservoirs: Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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GE-Hitachi economic simplified (ESBWR) Westinghouse Advanced Passive 600 MW (AP600) Nuclear fission The Oklo reactor review Nuclear fusion • At a enrichment facility in France, uranium supplies were Lasers: NIF/LLNL found to have not 0.7202% 235U but 0.7171%. How could that be? Nuclear weapons

Manhattan Project • Exploration of the site of uranium ore—the Oklo Mine in Gabon, 235 U Central Africa—revealed that some ores from the site had values as 239 Pu 235 Trinity low as 0.440% U! Hiroshima and Nagasaki • Conclusion: some induced fission took place due to high enough Fusion weapons uranium concentrations in the ground, with groundwater as a Example nuclear weapons moderator! Consistent with Nd and Ru distributions. • This all happened about 2 billion years ago, when 235U concentrations were higher planet-wide (t1/2 = 700 million years). • Non-volatile fission products in the deposit have traveled only centimeters over 2 billion years. • See July 1976 and Nov. 2005 issues of Scientific American. Nuclear fission Producing electricity review

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Manhattan Project Nuclear 235 U 19.27% 239 Natural gas Pu 2011 Sources of Electrical 24.79% Trinity (www.eia.gov) Hiroshima and Hydro Nagasaki 7.93% Fusion weapons Wind 2.92% Wood 0.90% Example nuclear Oil 0.69% weapons Coal 42.29% Geothermal 0.41% Other gases 0.27%

Solar 0.04% Waste 0.48% Nuclear fission Electricity alternatives review

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Manhattan Project 235 U 239 Pu • Trinity Hydroelectric power is great where it’s available... Hiroshima and Nagasaki • Solar and wind power are both intermittent, and require significant Fusion weapons energy storage, and fossil fuel or backup. Example nuclear weapons • Coal is the cheapest fossil fuel, but is the “dirtiest” in terms of CO2 output, production hazards (worker safety), environmental hazards (mountaintop removal, acid rain), health hazards (particulates, radioactivity). Nuclear fission Coal mining safety review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Recent history review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Mountaintop removal review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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http://www.ohvec.org/galleries/mountaintop_removal/007/21.html Nuclear fission What to say about nuclear fission review

Nuclear ? Lasers: NIF/LLNL • Nuclear power produces electrical energy without significant Nuclear weapons release of CO2 into the atmosphere. This is of increasing Manhattan Project 235 significance in minimizing future global warming. U 239 Pu • Fraction of electricity generated from nuclear power varies from Trinity Hiroshima and country to country. US: 20%. France: 78%. Germany: 28%. Japan Nagasaki (pre-Fukushima): 26%. Fusion weapons • Reactors cannot explode like nuclear . Water reactors shut Example nuclear weapons off with loss of coolant, though with much economic damage (Three Mile Island) and even radionuclide release (Fukushima). Graphite reactors can run away with much greater release and destruction (Chernobyl). • In normal operation, nuclear power plants emit less radiation than coal-burning power plants! See McBride et al., Science 202, 1045 (1978), Table 4. Burning coal releases which can be incorporated by plants (food chain) or inhaled along with coal combustion particulates. Estimated radiation dose from living near a coal plant: 0.32 mSv/year. For comparison, estimated dose from living near a pressurized water : 0.13 mSv/year. Nuclear fission Nuclear fusion review

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Lasers: NIF/LLNL • From the curve of binding energy, if we can cause light nuclei to Nuclear weapons fuse we can release even more energy per nucleon. Manhattan Project • 235 U Requires high density and high kinetic energy(=temperature) to 239 Pu overcome the Coulomb barrier. Trinity Hiroshima and • Nagasaki Fusion products have a short half-life and thus don’t present a

Fusion weapons long-term nuclear waste problem. However, all reactor materials

Example nuclear get flooded with so just about everything is made weapons radioactive. • One approach: extreme heating of a fusion pellet using lasers (interial confinement fusion or ICF). • Another approach: magnetically confined plasma (magnetically confined fusion or MCF). • The challenges are daunting! “Fusion is thirty years away”—a statement made beginning in the 1950s. “Fusion is the energy source of the future, and always will be.” Nuclear fission The Lawson criterion review Required temperature/density combination for energy breakeven. See Nuclear fusion

Lasers: NIF/LLNL also Serway Fig. 14-13.

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission TFTR at Princeton review Nuclear fusion Fusion Test Reactor. Operated 1982–1997 at Princeton Lasers: NIF/LLNL University. Nuclear weapons

Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Joint European Torus review

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Lasers: NIF/LLNL Oxfordshire, UK, 1983–1999 with some continued operation. An inside

Nuclear weapons view when “cold” and when operating:

Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission ITER review

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Lasers: NIF/LLNL ITER: International Toka-

Nuclear weapons mak Reactor

Manhattan Project (France; $20B with USA 235 U share of $2B). Goal is 239 Pu Trinity to demonstrate methods Hiroshima and Nagasaki to extract energy, and to Fusion weapons perhaps reach momentary Example nuclear weapons “engineering” breakeven.

As of 2009, the US had given a total of $27M to- wards ITER, or about 1/3 of the first-weekend ticket sales of the most recent Wolverine movie (NY Times, April 30, 2009). FY 2013: $178M. Nuclear fission Let’s go to Livermore review Nuclear fusion For the biggest, baddest laser around, let’s go to Livermore; it’s one of Lasers: NIF/LLNL the two nuclear weapons physics lab, along with Los Alamos in New Nuclear weapons Mexico. Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Livermore lab review

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Lasers: NIF/LLNL Lawrence Livermore National Lab. NIF is at the upper right.

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission NIF: National Ignition Facility review

Nuclear fusion Recently completed. Cost: $4.2B? Web site:

Lasers: NIF/LLNL http://www.llnl.gov/nif/ Nuclear weapons 192 beams (3072 slab amplifiers), total energy of 1.8 MJ, pulse duration 14 Manhattan Project 3–20 nsec. During those 3-20 nsec, the lasers emit a power of 5 × 10 235 U 12 239 Pu Watts. US electric power generating capacity: 1 × 10 Watts. Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission NIF: an aerial view review

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Lasers: NIF/LLNL About the size of a football stadium:

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission NIF components review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Part of one capacitor bank One replaceable amplifier slab on its mounting robot Nuclear fission NIF target chamber review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission NIF target chamber II, and review

Nuclear fusion Hohlraum

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Hohlraum leading to fusion review

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Lasers: NIF/LLNL Nuclear weapons Direct laser heating of pellet produced too many nonuniformities. Manhattan Project 235 U Indirect heating instead! 239 Pu Trinity Hiroshima and Nagasaki

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Mini H-. Relevant to understanding weapons, supernovae. Future energy source??? Nuclear fission 1983 review

Nuclear fusion Lasers: NIF/LLNL • 1983–4: Height of the Cold War between the USA and USSR. Nuclear weapons Each have more than 20,000 weapons, with many on rapid alert. Manhattan Project 235 U • USA putting Pershing II nuclear-armed missiles into Germany. 239 Pu Trinity Massive protests, such as 600,000 people in Berlin. Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Today review

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Lasers: NIF/LLNL The USSR is no more! Nuclear weapons • USSR ends production of highly in 1988. Manhattan Project 235 U • Nuclear weapons tests end after 1990. 239 Pu Trinity • Ukraine, Kazakhstan, and Belarus transfer their nuclear weapons to Hiroshima and Nagasaki Russia in 1993. Fusion weapons • Russia ends production in 2006. Example nuclear weapons The USA de-emphasizes nukes. • Plutonium production ends in 1989. • Production of highly enriched uranium ends in 1992. • Nuclear weapons tests end after 1992. May 2009: Obama and Medvedev agree to cut nuclear arsenals by another 25%.

So can we relax? Nuclear fission Nukes: forgotten, but not gone! review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Small nukes? Not so benign review • Hiroshima: 15 kt (kilotons of Reed & Stillman: Nuclear fusion

Lasers: NIF/LLNL TNT equivalent). 70,000

Nuclear weapons immediate deaths? Manhattan Project • Nagasaki: 21 kt. 35,000 235 U 239 Pu immediate deaths? Trinity Hiroshima and • Biggest nuke was 50,000 kt! But Nagasaki more typically 100–500 kt. Fusion weapons Example nuclear • Effects scale with square root of weapons yield.

Hiroshima (from Rhodes) Nuclear fission Fission cross sections review

Nuclear fusion Lasers: NIF/LLNL Cross sections for capture by 235U vary by orders of magnitude Nuclear weapons depending on the neutron energy. Manhattan Project 235 U Neutrons can be slowed using water, or , or graphite. 239 Pu Trinity Hiroshima and Nagasaki

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Australian Uranium Information Centre Nuclear fission Nuclear weapons: fission review

Nuclear fusion 235 Lasers: NIF/LLNL • If we have just pure U, the fast neutrons can produce a very fast Nuclear weapons chain reaction: an ! Concentrations required are perhaps Manhattan Project 80% or more for efficient weapons. 235 U 239 Pu • There’s a set by the interaction length of fast neutrons Trinity Hiroshima and (Rudolph Peierls, 1939). Thought to be less than 25 pounds: a 4” Nagasaki

Fusion weapons solid sphere (if it weren’t fissionable), or a 8” sphere with a 6”

Example nuclear hollow core! weapons • It’s relatively easy to make a uranium bomb: just slam together two uranium lumps like shooting a uranium bullet into a hollow uranium cylinder. The second (the one dropped on Hiroshima, Japan on August 6, 1945) was of this type, and was used untested. • The trick is this: how do you get several kg of nearly pure 235U when it’s only 0.72% of natural uranium? Done at Oak Ridge during WWII. 235 Nuclear fission Gun-type U bomb review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission for review

Nuclear fusion Basically a massive mass spectrometer. Very inefficient, and requires Lasers: NIF/LLNL

Nuclear weapons lots of electrical power to run magnet coils. Oak Ridge, .

Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission operators review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Gaseous diffusion for isotope review

Nuclear fusion separation

Lasers: NIF/LLNL Slight differential in diffusion rate through a membrane due to different Nuclear weapons

Manhattan Project masses (UF6 gas). Also very inefficient! 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission The K-25 plant close-up review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Implosion bombs using plutonium review

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Nuclear weapons Manhattan Project • By irradiating 238U with neutrons (such as in a nuclear reactor), one 235 U 239 239 Pu can transmutate some into Pu which is fissionable! Trinity 239 238 Hiroshima and • Because Pu has a different nuclear charge than U, it is Nagasaki

Fusion weapons possible to use chemistry to separate it out. Much easier than

Example nuclear isotope separation! Pioneered by Glen Seaborg, Berkeley. weapons • A challenge with 239Pu is that the fission neutrons are produced more quickly so “gun”-type assembly of a critical mass will lead to premature heating, expansion, and a “fizzle” of an explosion. • Solution: implosion of a hollow sphere. Very difficult to achieve, and there was uncertainty whether it would work so it was tested. Nuclear fission Trinity test core review

Nuclear fusion From , The Making of the Atomic Bomb: Lasers: NIF/LLNL

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Producing plutonium review Nuclear fusion A set of nuclear reactors were built in Hanford, eastern Washington, Lasers: NIF/LLNL where they could use the Columbia River for cooling water. This figure Nuclear weapons from Rhodes: Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Plutonium separation review

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Lasers: NIF/LLNL From Rhodes:

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Separation controls review Nuclear fusion From Rhodes: Lasers: NIF/LLNL

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Trinity test, , 1945 review

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Lasers: NIF/LLNL Near Alamogordo, . Sand underneath test tower was fused

Nuclear weapons into .

Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Use against Japan review • Following a series of brutal battles across islands in the Pacific Nuclear fusion ... Lasers: NIF/LLNL (Saipan, Iwo Jima ), some people predicted casualties of 1

Nuclear weapons million amongst US forces if an invasion of Japan were to be

Manhattan Project carried out. However, Japan was also in increasingly desperate 235 U straits by the end of . Some scientists from the Manhattan 239 Pu Trinity project urged that a bomb be demonstrated to the Japanese Hiroshima and Nagasaki leadership, but how to arrange? What if it fizzled? Fusion weapons • President Franklin Delano Roosevelt dies from a stroke in April 12, Example nuclear weapons 1945 and is succeeded by Vice President Harry Truman. • Hiroshima, August 6, 1945: home base for Japanese forces in Manchuria. Uranium gun-type bomb. Nagasaki, August 9, 1945: major war material production center and sea port. Plutonium implosion-type bomb. • In both cities, tens of thousands of immediate deaths from ∼ 15 kiloton TNT equivalent . For one account of the events, see the short book Hiroshima by John Hersey. • Japan surrenders, August 15, 1945. Were they preparing to surrender anyway? Or did Japan’s nuclear weapons physicists quickly understand what was going on? Nuclear fission and review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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USSR: copy of Fat Man tested on Aug. 29, 1949 before indigenous designs allowed. Nuclear fission Modern weapons: fission/fusion review Nuclear fusion • Fusion offers more energy release per mass. Lasers: NIF/LLNL

Nuclear weapons • Requires high temperature and compression. How can this be done

Manhattan Project when the fission trigger blows things out? 235 U 239 Pu • Solution: radiation pressure (focused X rays from trigger) to Trinity Hiroshima and compress and heat fusion fuel before neutrons arrive. Nagasaki • Fusion weapons First test: USA on Nov. 1, 1952, using liquid hydrogen (not

Example nuclear deliverable by airplane!) weapons • Use neutrons on 6Li to generate . First deliverable bomb: USSR, Aug. 12, 1953, then USA on Feb. 28, 1954. Nuclear fission Fission/fusion sequence review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Schematic of a bomb? review Nuclear fusion Source: Greenpeace UK, Federation of American Scientists. Lasers: NIF/LLNL

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission The Cold War review

Nuclear fusion Lasers: NIF/LLNL • At their peak around 1985, the US and USSR each had about Nuclear weapons 20,000–30,000 nuclear weapons. Manhattan Project 235 U • Nuclear testing: a total of about 2000 tests worldwide, including 239 Pu Trinity about 500 above-ground. Hiroshima and Nagasaki • Both the US and the USSR developed a triad of weapons delivery Fusion weapons systems: bombers, intercontinental ballistic missiles (∼30 minutes Example nuclear weapons “door-to-door delivery”), and missile-launching submarines. Other nations have one or two parts of such a triad. • Strategic weapons: destroy big targets in the interior of the opposing country (missile launch sites, command and control centers, and cities as a last resort). First strike; “use them or lose them.” • Tactical weapons: destroy troop concentrations, command centers, etc. on the battlefield. Nuclear fission Nuclear weapons tests review Nuclear fusion From Wikipedia: Lasers: NIF/LLNL

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission review

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Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Test “Buster-Jangle Dog,” Nevada Test Site, 1951.

Craters at the Nevada Test Site. Nuclear fission Perfecting nuclear weapons review

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Lasers: NIF/LLNL Nuclear weapons • The WWII bombs were very conservative in design. Manhattan Project 235 U • Weapons testing allowed various tricks to be perfected. 239 Pu • Improved conventional high exposives that won’t go off in accidents Trinity Hiroshima and (e.g., aircraft crash and fire). Nagasaki • Levitated implosion cores (to drive a nail, do you push with a Fusion weapons hammer, or swing it?) Example nuclear weapons • Small accelerators as neutron initiators. • 235U or 239Pu triggers with 238U fission boosts. • Improved radiation heating of Li-based fusion cores. • Permissive Action Links (PALs) of increasing sophistication, so that only a specific, secret electrical signal sequence will arm a bomb. • A danger: are US weapons too “tweaky” to be robust to ageing? Will they rust in peace? Codeword: stockpile stewardship. New generation of robust, simpler weapons? Nuclear fission Davy Crockett review Nuclear fusion Artillery with ∼ 2–4 km range. W-54 warhead: 11” diameter, 75 Lasers: NIF/LLNL pound weight, 0.25 kt yield. Tested in 1962. Nuclear weapons

Manhattan Project 235 U 239 Pu Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission The Tsar bomb review

Nuclear fusion Lasers: NIF/LLNL The Russian “Tsar” bomb: ∼ 50 Mt (dropped from an airplane in 1961). Nuclear weapons See Manhattan Project 235 U http://en.wikipedia.org/wiki/Tsar_Bomba 239 Pu A 1952 US test at 10 Mt vaporized a coral island in the Pacific. Trinity Hiroshima and Nagasaki

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Example nuclear weapons Nuclear fission Modern example: review Nuclear fusion • B61: developed by Los Alamos 1961–1968 (airplane-dropped Lasers: NIF/LLNL bomb; up to 340 kt). Nuclear weapons • Manhattan Project Smaller version sought for cruise missles; W80 developed by Los 235 U Alamos 1976–1982. 239 Pu Trinity • 290 pounds, dial-a-yield from 5–150 kt, 31” long, 12” diameter. Hiroshima and Nagasaki

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Example nuclear weapons