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Originally posted by RockerDom
but don't you think we'd have seen something of this before now if some of these nukes were sold?
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The smallest possible bomb-like object would be a single critical mass of plutonium (or U-233) at maximum density under normal conditions. An unreflected spherical alpha-phase critical mass of Pu-239 weighs 10.5 kg and is 10.1 cm across.
A single critical mass cannot cause an explosion however since it does not cause fission multiplication, somewhat more than a critical mass is required for that. But it does not take much more than a single critical mass to cause significant explosions. As little an excess as 10% (1.1 critical masses) can produce explosions of 10-20 tons. This low yield seems trivial compared to weapons with yields in the kilotons or megatons, but it is actually far more dangerous than conventional explosives of equivalent yield due to the intense radiation emitted.
A mere 1.2 critical masses can produce explosive yield of 100 tons, and 1.35 critical masses can reach 250 tons. At this point a nation with sophisticated weapons technology can employ fusion boosting to raise the yield well into the kiloton range without requiring additional fissile material.
The amount of fissile material that constitutes a "critical mass" varies with the material density and the type of neutron reflector present (if any). A high explosive implosion can compress fissile material to greater than normal density, thus reducing the critical mass. A neutron reflector reduces neutron loss and reduces the critical mass at a constant density. However generally speaking, adding explosives or neutron reflectors to a core adds considerably more mass to the whole system than it saves.
A limited exception to this is that a thin beryllium reflector (thickness no more than the core radius) can actually reduce the total mass of the system, although it increases its overall diameter. For beryllium thicknesses of a few centimeters, the radius of a plutonium core is reduced by 40-60% of the reflector thickness. Since the density difference between these materials is on the order of 10:1, substantial mass savings (a couple of kilograms) can be achieved. At some point though increasing the thickness of the reflector begins to add more mass than it saves since volume increases with the cube of the radius. This marks the point of minimum total mass for the reflector/core system.
A low yield minimum mass or minimum volume weapon would thus use an efficient fissile material (plutonium or U-233), a limited amount of high explosives (sufficient only to assembly the core, not to compress it to greater than normal density), and a thin beryllium reflector.
We can now try to estimated the absolute minimum possible mass for a bomb with a significant yield. Since the critical mass for alpha-phase plutonium is 10.5 kg, and an additional 20-30% of mass is needed to make a significant explosion, this implies 13 kg or so. A thin beryllium reflector can reduce this by a couple of kilograms, but the necessary high explosive, packaging, triggering system, etc. will add mass, so the true absolute minimum probably lies in the range of 11-15 kg (and is probably closer to 15 than 11).
This is probably a fair description of the W-54 Davy Crockett warhead. This warhead was the lightest ever deployed by the US, with a minimum mass of about 23 kg (it also came in heavier packages) and had yields ranging from 10 tons up to 1 Kt in various versions. The warhead was basically egg-shaped with the minor axis of 27.3 cm and a major axis of 40 cm. The test devices for this design fired in Hardtack Phase II (shots Hamilton and Humboldt on 15 October and 29 October 1958) weighed only 16 kg, impressively close to the minimum mass estimated above. These devices were 28 cm by 30 cm.
The W-54 nuclear package is certainly light enough by itself to be used in a "suitcase bomb" but the closest equivalent to such a device that US has ever deployed was a man-carried version called the Mk-54 SADM (Small Atomic Demolition Munition)...It was a cylinder 40 cm by 60 cm, and weighed 68 kg...
Nuclear artillery shell designs with diameters as small as 105 mm have been studied. Packaging a nuclear artillery shell in a suitcase is an obvious route for creating a compact man-portable device.
The US has developed several nuclear artillery shells in the 155 mm caliber. The only one to be deployed was the W-48 nuclear warhead developed by UCRL, packaged in the M-45 AFAP (artillery fired atomic projectile) shell. The W-48 nuclear warhead measured 86 cm (34") long and weighed 53.5-58 kg (118-128 lbs).
The smallest diameter US test device publicly known was the UCRL Swift device fired in the Redwing Yuma shot on 28 May 1956 . It had a 5" (12.7 cm) diameter, a length of 62.2 cm (24.5 inches) and weighed 43.5 kg (96 lb). The test had a yield of 190 tons, but was intended to be fusion boosted (and thus would probably have had a yield in the kiloton range) but its yield was insufficient to ignite the fusion reaction and it failed to boost in this test.
Later and lighter 155 mm designs were also developed -- the W74 (canceled early in development), and the W-82/XM-785 shell. The W82 had a yield of up to 2 kilotons and weighed 43 kg (95 lb), but included a number of sophisticated additional features within this weight...capable of being fielded with a "neutron bomb" (enhanced radiation) option, which is intrinsically more complex than a basic nuclear warhead...the actual minimum nuclear package was substantially lighter than the weight of the complete round. Its overall length was 86 cm (34").
Compact nuclear artillery shells (208 mm and under) are based on a design approach called linear implosion.
It is quite likely, that should the suitcase bombs described by Lebed actually exist, that they would use this technology. It is clear that any of the 155 mm artillery shells, if shortened by omitting the non-essential conical ogive and fuze would fit diagonally in the package that Lebed describes, and the Swift device would fit easily. If the yield is as much as 10 kilotons, then the device would have to be fusion boosted.
RockerDom wrote
Unfortunately, the possibility of this venture becomes more and more remote the more I research it. Every article I find in support of it is full of conjecture on possibilities, but the debunking articles are full of facts. At a certain point a nuclear weapon cannot function. Remember, the plutonium must be detonated by an outside explosion, and then contained long enough for a fusion reaction to happen.
After researching this, I simply cannot believe that these weapons exist, or that they could exist. There just isn't evidence to support it.
A series of satellites planned to begin deployment in 1989 (temporarily delayed by the Shuttle explosion) are now aloft (2nd phase of the MILSTAR Program) They carry special sensor devices (Developed by SAIC) that can detect high-velocity spin-off particles from enriched uranium (necessary for nuclear devices). Due to the small size and velocity of these particles, no amount of shielding can block them: not lead, not earth (sub-terrainian). Radiation hazards from these particles are minimal due to limited quantity. Our satellites are fool-proof in detecting and pin-pointing the locations of enriched uranium throughout the world.
The nuclear verification process employed in monitoring Iraq and other nations via NATO and the United Nations uses these satellite joint detection systems (the NSA controls and tracks the data). Many articles concerning these satellites have already been written in specialty magazines (Defense Science and Electronics-for one). Any attempt to bring a nuclear device into our country would be instantly detected (not to mention the track of its mobile transport).
Originally posted by RockerDom
Did you read any of my research esdad? I'm not attacking you, or anything, but the original claims come from someone who's crediblity and motives have been called into question numerous times. The weigh is not even the major problem, but the mass required to obtain a nuclear explosion. It is simply too small of a device to actually work.
The smallest device known that would actually work that terrorists may have would be something the size of a steamer trunk. The problem with these is that all are accounted for, and it takes a team of men to keep up with and detonate, plus a renewable, constant power supply. Even if terrorists had one, it would cost them over half a million dollars a week to keep up with, and a team of 5 or 6 men, plus incredibly logistics problems.
This is simply not a real threat.
The closest the U.S. is known to have come to a "suitcase" or hand-carried weapon was a variation of the W-54 called, interestingly enough, the SADM (small atomic demolition munition). This device -- officially the Mk-54 -- would have required a mighty big suitcase. It was a fat cylinder, 15 inches (diameter) by 24 inches, not unlike one of those big plastic buckets you can buy bulk paint in at Home Depot, and it weighed 150 pounds.
Of course a nuclear weapon gives off a significant signature in the form of both gamma rays and neutrons. A huge effort is being made to employ a variety of gamma and neutron spectrometry devices at ports of entry and the perimeters of potential targets. But these devices (and more sophisticated ones are now being worked on at the national laboratories) are not foolproof. Distance, shielding of various types (tungsten, lead, steel of a given thickness) and the problem of false positives and false negatives are some of the challenges now being wrestled with by detection experts.
In the end, an atomic bomb in a suitcase is really just a metaphor, not only for the portability of nuclear weapons but for the new and ominous possibility of who might be carrying them. The fictional tweedy professor who terrorized London in "Seven Days to Noon" was a misguided idealist with a bomb in a satchel. Those who now seek to terrorize the West and particularly the United States are hate-filled killers who have glorified suicide as a virtue and are bending every effort to secure and use "the bomb," be it in a suitcase, a packing crate, a car or whatever will surreptitiously deliver it to target. "If" is not the question. Where and when are.
The infamous Soviet-made suitcase bombs that supposedly disappeared from inventory sometime after the break-up of the Soviet Union have been the subject of numerous investigations and much fevered speculation. It is known that the Soviets, like the United States, developed small nuclear munitions, small enough to be fired in artillery shells or to be hand-carried (by one or more soldiers) as a demolition device. If they designed and built one that could actually fit in a large brief case, one of them has not shown up anywhere, nor has an official photograph or blueprint of it.
The ones described by Soviet General Alexander Lebed, in sensational Congressional hearings back in 1997, were supposedly in suitcases approximately 24 x 16 x 8 inches. A mock-up of such a bomb, using the warhead of an American nuclear artillery shell, was constructed and, indeed, all the necessary items -- neutron generators, batteries, arming mechanism etc. -- were successfully stuffed in around the cylindrical device itself.
The starting point would be a critical mass of plutonium or U-233. This would be a sphere about 4 or 5 inches in diameter and weighing roughly 28 to 30 pounds. Since the carriers of the weapon would presumably be in close quarters with it for some period of time, the critical mass would have to be of "supergrade" plutonium, which would be relatively safe to handle because it gives off lower neutron emissions. Beyond that, design variations (neutron reflector, high explosive, trigger type etc.) and the packaging for the device would add to size and weight depending on materials used, ingenuity of layout and other factors.
The smallest one the U.S. ever deployed in its arsenal was the M-45, which could be fired from a 155 mm cannon. It was 6.1 inches in diameter (caliber) and 34 inches long. It weighed up to 128 pounds. Remove the conical tip and fuse from one of those and you reduce the length enough to barely fit diagonally in the Soviet-sized suitcase.
But, hey, why not a larger suitcase? Or a crate, or a strong cardboard box? How about the trunk of a car? The possibilities for concealing or disguising a nuclear weapon are endless. Take a look, for instance, at one of those high-capacity air compressors you can buy in any Sears hardware department.
The big question is the shelf-life and availability of nuclear artillery shells. The U.S. shells are apparently accounted for and secure. Whether all the Soviet era mini-warheads can be accounted for is another story.
The shelf-life issue is important. If there is a nuclear munition or more than one "out there," its condition could be in question. A nuclear weapon involves the melding of a variety of materials in close proximity -- metals, plastics, ceramics, exotic high explosives and, of course plutonium and uranium. Things happen inside a nuclear weapon even when it is just sitting.
The plutonium core gives off quite a bit of heat. This will warm the other parts of the weapon up to as much as 100 degrees Fahrenheit. Uranium "rusts" in much the same manner as steel when exposed to the air. And even though warheads are sealed in airtight metal containers, the materials inside -- the explosives and plastic, for instance -- give off trace amounts of oxygen, hydrogen and water vapor that can eventually cause oxidation and corrosion, both of which are abetted by the weapon's intrinsic heat. The high explosives in the detonating "lenses" of a weapon also have been known to deteriorate.
In the end, an atomic bomb in a suitcase is really just a metaphor, not only for the portability of nuclear weapons but for the new and ominous possibility of who might be carrying them. The fictional tweedy professor who terrorized London in "Seven Days to Noon" was a misguided idealist with a bomb in a satchel. Those who now seek to terrorize the West and particularly the United States are hate-filled killers who have glorified suicide as a virtue and are bending every effort to secure and use "the bomb," be it in a suitcase, a packing crate, a car or whatever will surreptitiously deliver it to target. "If" is not the question. Where and when are.
Originally posted by IMMORTAL
I believe that the United State already has and produces nuclear weapons. Now, what's to stop agents of the U.S Government from selling these on the Black Market to terrorists already in the United States? They already admit they're waiting to strike within U.S.A. The only nukes that would be possibly used are those made by the USA, with a made in the USA stamp.