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I know that with a Pancake probe that can read alpha you can get up to 30K CPM on a small plate. I ordered a 6" red plate off ebay and measured outside the box when it came in. It registered around 200 CPM on a CDV-700 with the beta shield open set against the box with the plate in it.

I did some calculations and came up with a rough estimate of 109 grams of uranium inside the glaze on the plate. I don't know if it is natural uranium or DU as they were manufactured using both and I lack the proper tools to find out.

Edited question: What would be the estimated dose rate of 109 grams of uranium per day/year?

Thank you for your time and help.

Here is a picture for reference: CPM of Feistaware plate outside of box

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    $\begingroup$ 1) Straight Dope. 2) XKCD Radiation Chart $\endgroup$ – RedGrittyBrick Oct 8 '15 at 14:10
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    $\begingroup$ Wait - you think betas and alphas are getting through the box? What does your meter read away from the box? $\endgroup$ – Jon Custer Oct 8 '15 at 14:13
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    $\begingroup$ AFAIK, "dangerous" isn't something quantifiable by physicists. You could ask whether this is a reasonable value from the source given its history, or something along those lines. $\endgroup$ – Kyle Kanos Oct 8 '15 at 14:19
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    $\begingroup$ That said, look at the uranium decay chains. Most of the energy is in alphas and betas. Short penetration depths. Most of the photons are pretty low energy, too. I leave my orange salt-shaker (reads tens of counts per second at the top surface on our classroom demonstration counter) in a cardboard box on the other side of my office and don't worry about it because I'm surely getting more dose from the K-40 in the cinder-block walls. $\endgroup$ – dmckee Oct 8 '15 at 14:51
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    $\begingroup$ I'm voting to close this question as off-topic because it's about health risks from radiation not physics $\endgroup$ – John Rennie Oct 8 '15 at 15:29
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It's likely not dangerous, especially sitting in your garage. A count rate reading from a GM tube tells you very little. Not only is there no information about the energy of the radiation being recorded, you make no mention of the distance your probe was from the source during the time of the reading. You also failed to specify a background count rate. A scintillation detector or even an ionization chamber would be more apt to tell you what you're dealing with (likely trace uranium).

If you don't feel safe eating off of it don't, but it won't pose a threat to your health by owning it. The total amount of activity in the entire plate is likely on the order of a microcurie or much less.

A good reference on the subject would be G. Knoll's "Radiation Detection and Measurement"

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Even in your "reference article" it it said: "The actual amount of radioactivity is extremely low -less than the normal background radiation you get from rocks and stuff" and "if in fact it's a problem, is that uranium is a heavy metal, as is lead [;]both could leach into food, particularly if it's acidic." So if you really wonder the risk for your health, don't measure it with a radiometer ! (any kind of heavy metal, in particular any isotope of uranium, is then the issue, while only some kind is radioactive).

Further, in physics as in biology, quantities is a key thing. If you extract 100% of the paint of a plate in order to eat it all, how much nanograms of heavy metal it makes ? which proportion would be absorbed by your intestine ? Compare to the recommendation thresholds. Then, in physics as in biology, comparisons and proportion is also a key thing. Among all the risks you have around you, even just those related to food and eating, what would be the order of importance of this one in the ordered list ? When was your fridge disinfected for the last time ? How fresh and isolated was the food ? How rinsed were the dishes ? (and are you sure of the metal of the spoon ? or the air of the room ?). In term of food-related risk it seems that many fantasy or true but very small things are in focus, while people seems to have totally forgotten that our very first historical enemy are bacteria (more bleach everywhere, please. And avoiding uncooked and cooked chicken sharing a same plate in a row is probably way more important than the paint below).

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