Bush Threatens to Nuke Wikipedia for Having Nuclear Weapon Knowledge

Since the Bush/Cheney Junta is salivating like a mad dog over the prospects of bombing Iran into oblivion for allegedly having the "knowledge" of how to build a nuclear weapon, shouldn't these mad dogs of the Potomac be sending B-2 bombers and Tomahawk cruise missiles to "wipe off the face of the earth" Wikipedia for their not only having the knowledge of how to build nukes, but publicly showing in intimate detail to the world how to construct these weapons?

P.S. Maybe Wiki can nickname their first two nukes after the ones used by the U.S. during WW II.

The could name one "Little Boy", in honor of his Highness, George the Bush and the other, "Fat Man", in honor of the crazy as loon Cheney.

Nuclear weapon design - Wikipedia, the free encyclopedia

Fusion

Fusion cannot be self-sustaining because it does not produce the heat and pressure necessary for more fusion. It produces neutrons which run away with the energy. In weapons, the most important fusion reaction is called the D-T reaction. Using the heat and pressure of fission, hydrogen-2, or deuterium ( 2D), fuses with hydrogen-3, or tritium ( 3T), to form helium-4 ( 4He) plus one neutron (n) and energy:[7]

Notice that the total energy output, 17.6 MeV, is ten times less than that with fission, but the ingredients are almost fifty times less massive, so the energy output per kilo is greater. However, in this fusion reaction 80% of the energy, or 14 MeV, is in the motion of the neutron which, having no electric charge and being almost as massive as the hydrogen nuclei that created it, can escape the scene without leaving its energy behind to help sustain the reaction – or to generate x-rays for blast and fire.

The only practical way to capture most of the fusion energy is to trap the neutrons inside a massive bottle of heavy material such as lead, uranium, or plutonium. If the 14 MeV neutron is captured by uranium (either type: 235 or 238) or plutonium, the result is fission and the release of 180 MeV of fission energy, which will produce the heat and pressure necessary to sustain fusion, in addition to multiplying the energy output tenfold.

Fission is thus necessary to start fusion, to sustain fusion, and to optimize the extraction of useful energy from fusion (by making more fission). In the case of a neutron bomb, see below, the last-mentioned does not apply since the escape of neutrons is the objective.

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Tritium production

A third important nuclear reaction is the one that creates tritium, essential to the type of fusion used in weapons and, incidentally, the most expensive ingredient in any nuclear weapon. Tritium, or hydrogen-3, is made by bombarding lithium-6 ( 6Li) with a neutron (n) to produce helium-4 ( 4He) plus tritium ( 3T) and energy:[7]

A nuclear reactor is necessary to provide the neutrons. The industrial-scale conversion of lithium-6 to tritium is very similar to the conversion of uranium-238 into plutonium-239. In both cases the feed material is placed inside a nuclear reactor and removed for processing after a period of time. In the 1950s, when reactor capacity was limited, for the production of every atom of tritium the production of an atom of plutonium had to be dispensed with.

The fission of one plutonium atom releases ten times more total energy than the fusion of one tritium atom, and it generates fifty times more blast and fire. For this reason, tritium is included in nuclear weapon components only when it causes more fission than its production sacrifices, namely in the case of fusion-boosted fission.

However, an exploding nuclear bomb is a nuclear reactor. The above reaction can take place simultaneously throughout the secondary of a two-stage thermonuclear weapon, producing tritium in place as the device explodes.

Of the three basic types of nuclear weapon, the first, pure fission, uses the first of the three nuclear reactions above. The second, fusion-boosted fission, uses the first two. The third, two-stage thermonuclear, uses all three.

Pure fission weapons

The first task of a nuclear weapon design is to rapidly assemble, at the time of detonation, more than one critical mass of fissile uranium or plutonium. A critical mass is one in which the percentage of fission-produced neutrons which are captured and cause more fission is large enough to perpetuate the fission and prevent it from dying out.

Once the critical mass is assembled, at maximum density, a burst of neutrons is supplied to start as many chain reactions as possible. Early weapons used an "urchin" inside the pit containing non-touching interior surfaces of polonium-210 and beryllium. Implosion of the pit crushed the urchin, bringing the two metals in contact to produce free neutrons. In modern weapons, the neutron generator is a high-voltage vacuum tube containing a particle accelerator which bombards a deuterium/tritium-metal hydride target with deuterium and tritium ions. The resulting small-scale fusion produces neutrons at a protected location outside the physics package, from which they penetrate the pit. This method allows better control of the timing of chain reaction initiation.

The critical mass of an uncompressed sphere of bare metal is 110 lb (50 kg) for uranium-235 and 35 lb (16 kg) for delta-phase plutonium-239. In practical applications, the amount of material required for critical mass is modified by shape, purity, density, and the proximity to neutron-reflecting material, all of which affect the escape or capture of neutrons.

To avoid a chain reaction during handling, the fissile material in the weapon must be sub-critical before detonation. It may consist of one or more components containing less than one uncompressed critical mass each. A thin hollow shell can have more than the bare-sphere critical mass, as can a cylinder, which can be arbitrarily long without ever reaching critical mass.

A tamper is an optional layer of dense material surrounding the fissile material. Due to its inertia it delays the expansion of the reacting material, increasing the efficiency of the weapon. Often the same layer serves both as tamper and as neutron reflector.

Gun assembly

1. Explosive 2. Gun barrel 3. Hollow uranium "bullet" 4. Cylinder target

Main article: Gun-type fission weapon

Little Boy, the Hiroshima bomb, used 140 lb (64 kg) of Uranium with an average enrichment of around 80%, or 112 lb (51 kg) of U-235, just about the bare-metal critical mass. (See Little Boy article for a detailed drawing.) When assembled inside its tamper/reflector of tungsten carbide, the 140 lb was more than twice critical mass. Before detonation, it was separated into two sub-critical pieces, one of which was later fired down a gun barrel at the other. About 1% of the uranium underwent fission; the remainder, representing 98% of the entire wartime output of the giant factories at Oak Ridge, scattered uselessly.[citation needed]

The inefficiency was caused by the speed with which the uncompressed fissioning uranium expanded and became sub-critical by virtue of decreased density. Despite its inefficiency, this design, because of its shape, was adapted for use in small-diameter, cylindrical artillery shells (a gun-type warhead fired from the barrel of a much larger gun). Such warheads were deployed by the U.S. until 1992, accounting for a significant fraction of the U-235 in the arsenal.

Plutonium pit

The core of an implosion weapon – the fissile material and any reflector or tamper bonded to it – is known as the pit. Some weapons tested during the 1950s used pits made with U-235 alone, or in composite with plutonium,[8] but all-plutonium pits are the smallest in diameter and have been the standard since the early 1960s.

Casting and then machining plutonium is difficult not only because of its toxicity, but also because plutonium has many different metallic phases. As plutonium cools, changes in phase result in distortion. This distortion is normally overcome by alloying it with 3–3.5 molar% (0.9–1.0% by weight) gallium which causes it to take up its delta phase over a wide temperature range.[9] When cooling from molten it then suffers only a single phase change, from epsilon to delta, instead of the four changes it would otherwise pass through. Other trivalent metals would also work, but gallium has a small neutron absorption cross section and helps protect the plutonium against corrosion. A drawback is that gallium compounds themselves are corrosive and so if the plutonium is recovered from dismantled weapons for conversion to plutonium dioxide for power reactors, there is the difficulty of removing the gallium.

Because plutonium is chemically reactive and toxic if inhaled or enters the body by any other means, for protection of the assembler, it is common to plate the completed pit with a thin layer of inert metal. In the first weapons, nickel was used but gold is now preferred.[10]

Two-point linear implosion

A very inefficient implosion design is one that simply reshapes an ovoid into a sphere, with minimal compression. In linear implosion, an untamped, solid, elongated mass of Pu-239, larger than critical mass in a sphere, is imbedded inside a cylinder of high explosive with a detonator at each end.[12]

Detonation makes the pit critical by driving the ends inward, creating a spherical shape. The shock may also change plutonium from delta to alpha phase, increasing its density by 23%, but without the inward momentum of a true implosion. The lack of compression makes it inefficient, but the simplicity and small diameter make it suitable for use in artillery shells and atomic demolition munitions - ADMs - also known as backpack or suitcase nukes.

All such low-yield battlefield weapons, whether gun-type U-235 designs or linear implosion Pu-239 designs, pay a high price in fissile material in order to achieve diameters between six and ten inches

Source: Wikipedia.org