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Uranium/Plutonium hot to the touch?

  1. Jun 1, 2009 #1
    (Hot here refers to temperature, NOT the obvious radioactivity),Yes, perhaps a silly question, but maybe not.

    I can't remember where I read about Russian children finding "radioactive" metal in a forest that had melted the snow around it.

    Perhaps they found metal that had been neutron bombarded, and the decay made this metal hot?

    Maybe the more enriched the Uranium or Plutonium the cooler, maybe "other" metals/elements absorb the decay and convert to heat?(actual Urainium/Plutonium not hot to the touch?)

    All speculation by me, any answers? Thanks, John
     
  2. jcsd
  3. Jun 1, 2009 #2

    mgb_phys

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    Pu is used as a heat source in generators for spacecraft, it's a bit expensive to have lying around in the coutryside but you never know.
    Pu238 is the most powerfull, it's a 5Mev alpha emitter with a half life around 85years.
    So around 6x10^11 decays/second/g * 1.6x10^-11J gives a power of 0.5W/g, they would have to be reasonably big
    lumps to melt snow.
     
  4. Jun 1, 2009 #3
    I'm sure (from memory) it was'nt plutonium or uranium the kids found, it was another metal that had been irradiated. This article is what made me think, is it the uranium/plutonium that is hot, or is it the other metals/elements around it, getting hot. Thanks
     
  5. Jun 1, 2009 #4
    Radioactive decay produces heat. This does not simply go linearly with the mass, but with plutonium and uranium you will have fission effects. The temperature increases massively the closer you come to the critical mass.
     
  6. Jun 1, 2009 #5

    f95toli

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    According to one of my books about the Manhattan project the plutonium for Trinity (the first bomb they tested) felt slightly warm when they touched it, but it wasn't hot so they could easily handle it when they assembled the bomb (I am not even sure they wore gloves, although considering hos toxic Pu is I hope so).

    Hence, if you leave a large piece of Pu in the snow it might very well melt some of it.

    Btw, isn't this what is suppose to have happened to the Pu in the bomb that was "lost" on Greenland? As far as I remember they found some of it but the Pu was gone, presumably because it had simply melted through the ice and then sunk into the sea underneath.
     
  7. Jun 1, 2009 #6

    Vanadium 50

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    The burning jet fuel probably had more of an effect on the snow.
     
  8. Jun 1, 2009 #7

    mgb_phys

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    I don't remember any such incident, there was a case in Georgia (IIRC) where a group of hunters camped on a bunch of warm barrels they found in the woods. They were sources from a seed irradiation facility, so were probably Co or Sr.

    In a RTG the plutonium gets hot and the heat generates electricity. Ultimately the heat transfers to the cooling vanes on the outside of the package. You can think of the Pu source as just an electric heater with a battery that lasts 100s of years.

    The Russians do (or did) use a lot of them to power unmanned installations in the arctic - weather stations, radio beacons etc (there isn't a lot of sunlight for solar power), so they might have lost a few.
     
  9. Jun 1, 2009 #8
    Great info! Thanks
     
  10. Jun 1, 2009 #9

    QuantumPion

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    The Russians used RTG's to power remote facilities such as lighthouses. During the fall of the Soviet Union, many of these RTG's went into disrepair or were stolen. I believe they contained Sr-90. Such a device would be hot to the touch, and very dangerous.
     
  11. Jun 1, 2009 #10
    Many years ago I worked at a govt facility that had a door propped open with a piece of D38 (U238) in a plastic bag. It was not warm to the touch.
     
  12. Jun 1, 2009 #11

    mgb_phys

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    U238's half life is about the age of the Earth so the activity is very low.
     
  13. Jun 1, 2009 #12

    rcgldr

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    As mentioned here, Plutonium "buttons" are used along with thermal couples to generate electicity for satellites intended to go long distances (away from Sun). The power source (is (or at least the buttons) are designed to withstand re-entry in case of a launch failure. The buttons also capture a significant part of the radiation coverting it to heat, but I doubt they are safe to handle long term. The only USA plutonium + thermal-couple generator I recall that was lost on earth, is the one from the lunar module from Apollo 13, it's at the bottom of some ocean, probably still generating potential power.

    U238 is fairly stable. Depleted Uranium was used as ballast in Formula 1 race cars until it was banned for cost (not hazard) reasons.
     
  14. Jun 1, 2009 #13

    Andrew Mason

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    I don't think the lunar module made it back to earth intact. It would have complete burned up on reentry.

    AM
     
  15. Jun 2, 2009 #14

    Vanadium 50

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    They had an RTG? I though the LEM was powered by fuel cells. Or was this for an experiment?
     
  16. Jun 2, 2009 #15

    QuantumPion

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    Didn't a Russian satellite powered by an RTG recently crash in Canada? I seem to remember the Canadian government making a fuss about Russia paying for the cleanup or something.
     
  17. Jun 2, 2009 #16

    rcgldr

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    "Because this mission was aborted, its RTG now rests in the South Pacific ocean, in the vicinity of the Tonga Trench."

    Wiki RTG .htm

    Since the lunar module was never planned to be returning to Earth, it had an RTG on board, apparently for an experiement intended to be left on the moon. I didn't mean to imply that the LEM was powered by that RTG, just that it had one on board. Read the article from the Wiki link above for more info, plus the link to Appollo 13.
     
    Last edited: Jun 2, 2009
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