What is the critical mass for a uranium 235 atomic bomb?
442120
Whoa, man, why do you want to know? Do you know how suspicious you look after 9/11? \n\nthe critical mass for U-235 is 15 kilograms.
109890
The American government made the bomb that was dropped on Hiroshima, they generally do not release the blueprints. I can tell you that it was a gravity bomb, a gun-type fission weapon, with 60 kg (130 pounds) of uranium-235 encased in a bomb.See picture below.
37488
An atomic bomb is composed of some heavy-duty explosives, U-235 or P-239, and a neutron source.\n\nThe neutron source is in the center, surrounded by the Uranium or Plutonium, and then the explosives. Upon detonation, the explosives explode simultaneously, crushing the nuclear material in on the neutron source. This causes the material to achieve critical mass and a massive chain reaction takes place. Very massive.
160185
try this website, I just did a search and this came up:\n\nhttp://nuclearweaponarchive.org/Nwfaq/Nfaq5.html
377079
it has the greatest mass
101213
You may already know the answer, but I'll give you credit for wording it precisely.\n\nThe answer is more than one (on average), because neutron losses mean it would be impossible to sustain a critical nuclear reaction (that is, a constant rate of nuclear reactions) if you had one or less than one (on average) per reaction, since it takes at least one neutron to cause a nuclear reaction.\n\nThe exact reaction that occurs and the byproducts produced will determine exactly how many you get per individual reaction, but *on average* you need to net >1.0 neutrons per reaction.  The more losses you have (due to poor shielding, absorbant material, etc.), the higher the number needs to be, but something like 1.2-1.5 should be fine.
773715
For each kilogram of uranium that undergoes fission, 0.1%, or 0.001 kilograms is changed to energy. Using Einstein's mass-energy equation, calculate the amount of energy released per 0.001 kilograms of uranium:\n\nE = m*c^2 = 0.001*(300000000^2) = 9*10^13 J\n\nIf energy costs $0.03 per megajoule (1,000,000 J):\n\nC (total cost) = (0.03/1000000) * 9*10^13 =  $2,700,000 per kilogram of uranium\n\nI hope this helps!
328638
I recollect seeing 200,000 to 250,000 for both cities, including the aftermath.  The Hiroshima bomb was a low yield 15 kiloton device.  The strategic devices today are around 400-500, while the tactical nukes range from .3 to 200.  Some world we live in.
528928
A centrifuge is a device that uses the principle of centrifugal force to cause the deposition (precipitation) of the more heavier component in a mixture subjected to centrifugal treatment.\n\nNatural uranium contains at most 0.7% U-235 (the fissionable isotope) and the rest is U-238.  This natural uranium is useless with respect to fission (Average nuclear warheads have enriched uranium of about 85% U-235).  So, it has to be enriched (more U-235 has to be concentrated) to levels at least about 2%, the minimum for nuclear reactors.  There are many ways of enriching uranium, but the common way is by gas centrifuging, where a centrifuge causes the precipitation of the heavier U-238 molecules to the insides of the cylinders, while the lighter u-235 molecules stay in the center.\n\nThe fuss here is that, if Iran manages to achieve enrichment levels of 5%, it can then slowly research its way to enrichment levels of 80%+, which is suitable to make nuclear warheads.\n\nCheck these links out for more information.\nhttp://en.wikipedia.org/wiki/Enriched_uranium
822340
Nothing to worry about. The main reason for using depleted uranium is mass. It makes excellent armor and at the same time doesn't have to be thick.
1170603
okay. well, in a nuclear reactor, uranium or plutonium is bombarded with neutrons in order to force it to split and release huge amounts of energy. elements with 92 protons and up will nearly always absorb a neutron and split without hesitating.\n\nin a nuclear reactor, the uranium is highly enriched, which means it contains certain uranium isotopes that are less stable than others, therefore making it easier to split (and it IS weapon grade). it is kept at what's called the critical mass level. subcritcal mass wont sustain a chain reaction, and supercritical mass will cause a runaway chain reaction, like in an atomic bomb. the control rods in the reactor can be pushed in and out of the core, which contains the uranium (U) or plutonium (Pu). when the rods are all the way in, the reaction comes to a halt, when they are all the way out (they never are) the reaction reaches supercritical levels and escapes control. (this happened at chernobyl). there are other ways for a reactor to reach the supercritical level, the control rod material plays a part, the coolant, and of course those controlling the reaction. control rod material is very important, because if the material the rods are made of do not absorb enough neutrons, they will allow the reaction to continue (this happened at chernobyl, the material actually caused an increase in reaction speed and power). the coolant must have a very low void coefficient, (the void coefficient tells how much of the liquid is gas pockets at any given time. water has a high void coefficient) or else the gas pockets will allow extra heat to build up, therefore allowing the reaction to escape control, and possibly melt the core, as what happened at Three Mile Island. \n\nin short, a nuclear reactor cannot cause a thermonuclear explosion, because all current nuclear reactors are fission reactors, and thermonukes are fusion. however, the fission reactors in operation CAN cause an explosion (and it IS a nuclear explosion. nuclear particles and waste material are ejected from the reactor when it explodes. this can cause acute radiation poisoning in surrounding area), if they are not very carefully, precisely, and intelligently monitored.
496427
Not sure of the question but... uranium ore is mostly composed of the isotope U-238 which does not support self-sustaining fission reaction very well.  Enrichment is the process of extracting and purifying U-235 which is much more potent for use in weapons.\n\nWell, rockeytj - it's a physics question.  It's not like anyone's going to do it tonight with a blender and some toothpicks.  It takes zillions dollars worth of equipment, not to mention tons and tons of uranium ore.
409660
235 Uranium + 1 neutron --> 140 Cesium + 93 Rubidium + 3 neutrons
445580
http://science.howstuffworks.com/nuclear-bomb.htm
662506
The density of granite or marble is 2,69 gr/cm3 = 2690 kg/m3\n\nThe approximate dimensions of a sarcophagus for a standard human length is; \nOuter dimensions: Length=2,1 mt; Width=0,7 mt; Height=1 mt\nInner dimensions: Length=2 mt; Width=0,6 mt; Height=0,9 mt\nThe volume of the stone is 0,39 m3. \n\nSo the approximate minimum weight of the sarcophagus is 0,39 x 2690 = 1049,1 kg. which is approximately equal to 1 tonnes.
194920
It depends.\n1) In nuclear power plants a moderator is used to reduce the neutrons' velocity and the chain reaction rate is thereby controlled.\n\nA typical 1000 MWe nuclear power station uses only about 24 tonnes per year of uranium fuel.\nwww.aph.gov.au/house/committee/isr/uranium/subs/sub5.pdf\nOR\nhttp://www.uic.com.au/whyu.htm\n\nThe average reaction rate would calculate as follows:\n\n(24 tonnes/year) X (1000 kilograms/tonne) x (year/365 days)=\n                 66 kilograms/day (about 145 pounds a day)\n\n                   OR\n(66 kilograms/day) x day/24 hours x hour/60 minutes x 1000grams/kilogram =\n\n                 46 grams every minute \nThis is the weight of one typical (1.55 ounce) candy bar!\n\n2) In a nuclear bomb the neutrons are not moderated.\nThe reaction time for a bomb is 1/1000 second. (Complicated quote below.)\n\n "An explosion is an interplay between the total amount of energy released, energy density, and the time in which the energy is released. The time factor is perhaps the easiest to define. While there is no exact definition of reaction time for an explosion, we use one millisecond as a reasonable value to distinguish a steady-state regime from an explosive regime."                      \n\nhttp://www.ieer.org/ensec/no-6/fusion.html\n\nThe reaction rate calculation for a very small bomb (10 kilograms):\n\n10 kilograms / 1/1000 seconds = 10,000 kilograms/second !\n                       OR\n                217,391 candy bars per second!\n\nSummary:\n Nuclear Power Plant - Chain Reaction Rate \n 1 candy bar per minute\n\n Nuclear Bomb - Chain Reaction Rate\n 217,391 candy bars per second\n\nI haven't calculated candy bars per minute (Nuclear Bomb) because no one can eat that many in a minute.\n\n- Stan the Answer Man
823456
I wouldn't believe everything you read on wiki, especially things dealing with controversial topics like nuclear energy or stem cells.\n\nNow to answer your question, I suppose that depleted uranium could be used as a reflector in a bomb, but its effects will be marginal at best, lead probabally would be a better pick. Also if Uranium was a better reflector, you would be better off using natural Uranium than depleted Uranium. Its relativity easy to get both natural Uranium and lead so worrying about depleted Uranium rounds is kind of silly.