This experiment proved that anyone could design a nuclear weapon

  • Posted by a hidden member.
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    Jun 01, 2013 11:26 PM GMT
    Unfortunately and sadly, I suspect there will be a nuclear event in a major city in my lifetime...

    http://io9.com/this-experiment-proved-that-anyone-could-design-a-nucle-510618426

    In 1964, the US picked three young physics students who had gotten their PhDs in physics but hadn't had any specific education on weapons. They were given a salary, a basic support staff, and all publicly available information on nuclear weapons. They were then asked to design a nuclear bomb. The United States wanted to know if a small number of bright people, with sufficient motivation and the knowledge that such bombs were possible, could come up with the right design. No one had to wait too long. In 1967, the PhDs presented the officials of the Nth Country Experiment with a design for, what all the established bomb designers agreed, was a working atomic bomb. The design was a little over-fussy, but it was functional and, with a larger staff, or a little experimentation, it wouldn't take long to refine.

    The results of the Nth Country Experiment were not comforting, but they did shed light on what delays countries in building nuclear weapons. Clearly, it's not technical expertise in the design of the bomb.
  • tennsjock

    Posts: 349

    Jun 03, 2013 2:16 AM GMT
    Try Physics for Future Presidents by Richard Muller (U.C. Berkeley) for practical, very accessible explanations of the physics involved.

    Yes, designing a nuclear bomb is easy. Several designs are actually public knowledge already, and are included in the book. However, the technical expertise and precision involved in actually making a bomb is too high a threshold for just any group of people. It requires teams of PhD engineers and physicists, and only nations have the capacity.

    Then there's the problem of obtaining fuel. Mining uranium requires a pretty large technical infrastructure. But even that is the easy part. Of the uranium in the earth's crust, 99.3% is U-238, and 0.7% is U-235. U-235 is fissile, and U-238, though radioactive, is not fissile. And a chunk of uranium must be refined to 90% U-235 to be "weapons-grade". Because these two isotopes of uranium are chemically identical, separating U-235 from U-238 is incredibly difficult. That's why Iran is having so much trouble refining enough uranium to make a thermonuclear device.

    I can't speak for other people, but learning more about the steps involved constructing a bomb actually reduced my fears about these weapons.
  • Whipmagic

    Posts: 1481

    Jun 03, 2013 2:24 AM GMT
    tennsjock saidTry Physics for Future Presidents by Richard Muller (U.C. Berkeley) for practical, very accessible explanations of the physics involved.

    Yes, designing a nuclear bomb is easy. Several designs are actually public knowledge already, and are included in the book. However, the technical expertise and precision involved in actually making a bomb is too high a threshold for just any group of people. It requires teams of PhD engineers and physicists, and only nations have the capacity.

    Then there's the problem of obtaining fuel. Mining uranium requires a pretty large technical infrastructure. But even that is the easy part. Of the uranium in the earth's crust, 99.3% is U-238, and 0.7% is U-235. U-235 is fissile, and U-238, though radioactive, is not fissile. And a chunk of uranium must be refined to 90% U-235 to be "weapons-grade". Because these two isotopes of uranium are chemically identical, separating U-235 from U-238 is incredibly difficult. That's why Iran is having so much trouble refining enough uranium to make a thermonuclear device.

    I can't speak for other people, but learning more about the steps involved constructing a bomb actually reduced my fears about these weapons.


    And it gets only harder from there, if you want to make a militarily useful bomb, instead of just a bulky, crude device. You want something small enough, and in the right shape, to mount on a missile. That means you'll have to go to plutonium, instead of uranium, and master a very complex task of using fast conventional explosives to re-shape an aspherical plutonium pit such that it becomes critical, and detonates completely. Not easy to do at all, you need sophisticated computer simulations, advanced metallurgy, a lot of experience with shaped high explosives, etc.
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    Jun 03, 2013 2:42 AM GMT
    Whipmagic said
    tennsjock said

    And it gets only harder from there, if you want to make a militarily useful bomb... you need sophisticated computer simulations, advanced metallurgy, a lot of experience with shaped high explosives, etc.


    Really? What sophisticated computers were available to the Manhattan Project? Why would a country such as Iran need to miniaturize a device so as to deliver it via missal when they could have a proxy (Hezbollah, etc.) sail or smuggle a larger device into a target country? Why do the teams of PhD engineers, metallurgists, and physicists need to be assembled, when the plutonium can be purchased from failed Soviet states? Just curious.
  • Whipmagic

    Posts: 1481

    Jun 03, 2013 2:59 AM GMT
    swimguychicago said
    Whipmagic said
    tennsjock said

    And it gets only harder from there, if you want to make a militarily useful bomb... you need sophisticated computer simulations, advanced metallurgy, a lot of experience with shaped high explosives, etc.


    Really? What sophisticated computers were available to the Manhattan Project? Why would a country such as Iran need to miniaturize a device so as to deliver it via missal when they could have a proxy (Hezbollah, etc.) sail or smuggle a larger device into a target country? Why do the teams of PhD engineers, metallurgists, and physicists need to be assembled, when the plutonium can be purchased from failed Soviet states? Just curious.


    It's not the computers itself, but the code you run on them. It's basically solving Navier-Stokes equations, in a highly nonlinear and turbulent regime. And, you need to have the correct parameters, many of which can be determined only experimentally. Also, just having the plutonium doesn't yet get you the proper implosion, you need to get it in the right form, trigger correctly shaped high explosives around it with microsecond precision, etc. All of that is far from trivial. Much easier, however, s making a crude uranium device. But something that need to be smuggled into a foreign country on a boat instead of shot on he tip of a missile to a relevant target is not a useful military weapon; it is an instrument of terror.
  • Posted by a hidden member.
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    Jun 03, 2013 3:04 AM GMT
    [quote][cite]

    It's not the computers itself, but the code you run on them. It's basically solving Navier-Stokes equations, in a highly nonlinear and turbulent regime. And, you need to have the correct parameters, many of which can be determined only experimentally.[/quote]

    You sound very knowledgeable. Are you a physicist?
  • Whipmagic

    Posts: 1481

    Jun 03, 2013 3:06 AM GMT
    swimguychicago said[quote][cite]

    It's not the computers itself, but the code you run on them. It's basically solving Navier-Stokes equations, in a highly nonlinear and turbulent regime. And, you need to have the correct parameters, many of which can be determined only experimentally.


    You sound very knowledgeable. Are you a physicist?[/quote]

    Yes.
  • Posted by a hidden member.
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    Jun 03, 2013 3:15 AM GMT
    More "useful" than even constructing a (relatively primitive) Hiroshima era weapon (Fat Man/Little Boy) to a terrorist organization or a state sponsoring terrorism would be dirty bombs - small devices that could scatter U-238 or perhaps radioactive isotopes of cobalt or thorium into a major reservoir or water delivery system, or a major transport hub.
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    Jun 03, 2013 3:22 AM GMT
    I can beat that....try this....

    http://en.wikipedia.org/wiki/David_Hahn

    and we were even in the same unit in the Marine Corps!!! He was a minor celebrity on Camp Lejeune....
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    Jun 03, 2013 6:47 AM GMT
    riddler78 saidUnfortunately and sadly, I suspect there will be a nuclear event in a major city in my lifetime...

    http://io9.com/this-experiment-proved-that-anyone-could-design-a-nucle-510618426

    In 1964, the US picked three young physics students who had gotten their PhDs in physics but hadn't had any specific education on weapons. They were given a salary, a basic support staff, and all publicly available information on nuclear weapons. They were then asked to design a nuclear bomb. The United States wanted to know if a small number of bright people, with sufficient motivation and the knowledge that such bombs were possible, could come up with the right design. No one had to wait too long. In 1967, the PhDs presented the officials of the Nth Country Experiment with a design for, what all the established bomb designers agreed, was a working atomic bomb. The design was a little over-fussy, but it was functional and, with a larger staff, or a little experimentation, it wouldn't take long to refine.

    The results of the Nth Country Experiment were not comforting, but they did shed light on what delays countries in building nuclear weapons. Clearly, it's not technical expertise in the design of the bomb.
    In other words, the only countries that have no nuclear weapons are the countries that have no smart people?
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    Jun 03, 2013 12:04 PM GMT
    I think the greater risk is from a 'dirty' bomb (a primitive device in which TNT or fuel oil and fertilizer are combined with highly radioactive materials), because its ingredients are relatively simple to acquire and put together.

    Imagine if a single piece of radioactive cobalt from a food irradiation plant were dispersed by an explosion at the lower tip of Manhattan. Typically, each of these cobalt "pencils" is about one inch in diameter and one foot long, with hundreds of such pieces often being found in the same facility. The entire borough of Manhattan would be so contaminated that anyone living there would have a one-in-a-hundred chance of dying from cancer caused by the residual radiation. It would be decades before the city was inhabitable again, and demolition might be necessary.

    ny-co_sm.jpg

    Fig. 2 Long-term Contamination Due to Cobalt Bomb in NYC - EPA Standards.

    Inner Ring: One cancer death per 100 people due to remaining radiation (5% increase)

    Middle Ring: One cancer death per 1,000 people due to remaining radiation (.5% increase)

    Outer Ring: One cancer death per 10,000 people due to remaining radiation (.05% increase): EPA recommends decontamination or destruction

    http://www.fas.org/faspir/2002/v55n2/dirtybomb.htm
  • Apparition

    Posts: 3529

    Jun 04, 2013 4:55 AM GMT
    bombs are a waste of time. This is the weak link. Thousands and thousands of miles of unguarded towers bolted together in completely unprotectable farms and wastelands. With a wrench, you will surrender to me in less than a month. Completely insecurable. You would be starving and dying in the cold or heat after day 4. All other terror attacks fail in comparisson. You cannot protect yourself from a transmission tower attack. No communications, no food, no money, no internet, no jobs, no medical, no construction, no elevators, no lights, no water, no traffic control, no anything. Stone age instantly.
    tower1.jpg