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Radiation-Monitoring Reveals Interesting Data

  1. May 15, 2015 #1
    Here's an article by a woman who obtained a radiation monitor and noted it's readings at various places she went:

    http://www.ratical.org/radiation/radMonData.html

    I have a question about this passage:

    Why would this clock be so radioactive?

    I am also baffled by this revelation:

    Why is it so radioactive in the sky?

    I started out doing a bit of research into the radioactivity of common food, due to my accidental discovery of the banana equivalent dose.
    http://en.wikipedia.org/wiki/Banana_equivalent_dose

    This lead to having to sort out units of radiation:
    http://www.nrc.gov/about-nrc/radiation/health-effects/measuring-radiation.html

    That site contains the following mysterious comparisons:

    What's mysterious is why 2 days in Denver should equal a whole year next door to a nuclear power plant. It required looking into. The answer is startling:

    http://www.theatlantic.com/national...ophe-youve-probably-never-heard-about/261959/

    Anyway, I'm not sure why a non-illuminated clock should be so radioactive, nor why the radiation is so extremely high in commercial jets.
     
  2. jcsd
  3. May 15, 2015 #2

    Borek

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    Cosmic radiation, you are not protected by 10 km of air. Known thing that pilots get much higher doses than surface dwellers. And doses at the sea level are lower than in Denver - for the same reason.
     
  4. May 15, 2015 #3

    russ_watters

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    You missed the real connection there: it is more radioactive in Denver than next to most nuclear plants because Denver is at 5000 feet higher elevation than most nuclear plants. Neither nuclear plants (from outside) nor jets emit radiation.
     
  5. May 15, 2015 #4

    f95toli

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    Note also there are many places in the world where the radiation levels are much higher than average because of the abundance of radioactive elements. The most famous example of this is radon gas (which can become a real health risk if it leaks into e.g. basements), but there are also areas where you can literally find rock on the ground with relatively high amount of e.g. uranium in them and they will be (mildly) radioactive. The west coast of Sweden is an example of such an area (the "radiation safety" part of the atomic physics course I took as an undergraduate was taught by a slightly mad radio-chemist. He had a collection of such rocks that he had found near the university)
    .
     
  6. May 15, 2015 #5

    Vanadium 50

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    And doesn't have a clue on how to read it. To wit: "In forty minutes I'd been exposed to 15,240 rads -- the same amount I would receive in 15 hours in my apartment." If that were true, she'd be immediately incapacitated and dead within a day or two.
     
  7. May 15, 2015 #6

    ZapperZ

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    Why do I have a feeling that this device hasn't been properly calibrated?

    Besides, cps is not a meaningful measure of radiation since one can set an instrument with varying level of sensitivity that would even register dark counts.

    This, btw, is a perfect illustration where just because the general public can get access to "data", it doesn't mean they know what to do with them or how to analyze/interpret them correctly.

    Zz.
     
  8. May 15, 2015 #7

    Ryan_m_b

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    XKCD has a great chart on relative values of radiation, it includes some interesting everyday examples like flying:
    https://xkcd.com/radiation/
     
  9. May 15, 2015 #8

    Vanadium 50

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    I don't think it's even at that level. I think she doesn't know how to read it.
     
  10. May 15, 2015 #9

    Bandersnatch

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    I like how he points out that the only kind of a phone that produces ionising radiation is the 'bananaphone'.
     
  11. May 15, 2015 #10
    For meaningful dose estimates one needs a calibrations for a specific radiation type. A reading from any instrument by itself is almost meaningless and at best can be used to compare radiation intensities of a specific type of radiation. Radiation monitoring and dosimetry is an extremely difficult activity. One must know the detectors sensitivities to various radiations, the type of radiation including its energy, the conversion factors from radiation fluence measurements ( i.e. detector corrected readings) to use in the absorbed dose calculations and finally a assignment of dose equivalence quality factor ( an estimate of the relative biological effect a specific type of radiation has on living tissue) for the final estimate of the biological effect.
     
  12. May 15, 2015 #11
    Cosmic radiation explains Denver and flying. What explains Atlanta and the clock?
     
  13. May 15, 2015 #12

    Borek

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    As it was already said in the thread level of background radiation in different places is different. Doesn't mean that's the exact reason in this particular case, but that's enough for me to be not surprised.
     
  14. May 15, 2015 #13

    russ_watters

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    It explains Denver vs Atlanta. There are no places with zero background radiation, so you can just compare levels in one place to another. The altitude explains the difference.
    Having no idea what the history of the clock is, there is no way to know why it is registering what it is.
     
  15. May 15, 2015 #14

    Vanadium 50

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    All evidence is that she doesn't know how to use the instrument. For all we know, she has it on "battery check" mode. Trying to explain measurements by someone who doesn't know how to make them is futile.
     
  16. May 15, 2015 #15
    I would imagine the composition of bedrock also matters. A large part of the heat trapped in the earth's crust is due or was due to radioactive decay - while small, certain kinds of rock will naturally exhibit more or less radioactivity.
     
  17. May 15, 2015 #16
    But from the comparisons, I glean that both Denver and Atlanta are high in background radiation. 2 days in Denver = 3 days in Atlanta = one coast to coast flight.

    Here's a map whereby you can compare the background radiation levels of US cities:
    http://radiationnetwork.com/

    Atlanta is high in elevation at 1,050 feet above sea level, but Denver is very much higher at 5,280 feet above sea level. So, I'm wondering if the buffering properties of the atmosphere against cosmic rays are perhaps non-linear in some way I don't understand, or if it's explained by something else, say, the soil there being more than usually radioactive like f95toli's west coast of Sweden. Or like the beaches at Guarapari, Brazil.

    My question about the clock has to do with not understanding the extent to which non-radioactive things can be rendered radioactive. I assume the clock is steel, maybe with some brass. They mention it came from the Navy. If this were the clock that was hung over the nuclear reactor in a nuclear powered ship, for example, would that explain it? Can iron, copper, tin, be rendered radioactive by exposure to naturally radioactive elements?
     
  18. May 15, 2015 #17
    Ryan's chart reveals that living in a stone, brick, or concrete building for a year is 3.5 times the exposure of a chest x-ray. A matter of the density of those materials?
     
  19. May 15, 2015 #18
    Brick/stone/concrete will contain traces of radioactive ore, such as uranium and thorium ores.
     
  20. May 15, 2015 #19
    Occasionally radioactive materials get recycled into new metal. This might explain a watch (or other metal object) with a higher than average radiation count. (Though I get the watch in this story checked by someone who knew what they were doing before calling the police.)

    I want to point out that radiation is natural. People fear it like they fear witchcraft. It's invisible and they don't understand it. But it's not that dangerous except in very large doses (or if eaten).

    We should monitor radiation collectively (like at college physics departments for example) because accidents do happen, but running in terror is not called for.
     
  21. May 15, 2015 #20
    Here's an interesting video on the subject. This guy always makes good videos.

     
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