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Readily-available radioisotope heat source for a Stirling engine?

  1. Sep 8, 2012 #1
    Hi folks...I'm new here, please go easy on me, it's been quite a long time since college physics! :-)

    I need a feasible and readily available heat source for a Stirling cycle engine. (It's a type of engine that runs off of hot air...google it and you'll see plenty of examples.) Is there a readily-available radioisotope that might work well as a heat source?

    I know that tritium is readily-available and low-energy enough to not pose any serious risks (as I understand it). You can buy tritium based key-chain lights that glow for 12 years or so off Ebay...LOL. I've read here that a metal container the size of a baseball filled with tritium would be noticeably warm. How much tritium would it take, and what metal would provide the most heat output? (I'd assume the metal container would need to be something drilled with lots of capillary-sized tunnels to create more surface area for the beta particles to collide with.) To work well and be capable of creating useable mechanical energy, a Stirling cycle engine needs something like a few hundred degree temperature differential. You most frequently see practical models run off of propane burners, etc, so it would have to produce the heat output roughly equivalent to that.

    If tritium isn't a good choice, what other radioisotopes might fit the bill? It would have to be legal and not tightly controlled in the USA. I know bananas allegedly have a high content of radioactive potassium, but I don't know of any source of that radioisotope mined from bananas...LOL.

    Just curious if this idea is even remotely feasible. Please post your thoughts or suggestions.

  2. jcsd
  3. Sep 8, 2012 #2


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    Nobody is going to sell you a source that puts out enough watts to run a heat engine. That's good, because you clearly don't have the expertise to do anything like this safely.
  4. Sep 8, 2012 #3
    I've already stated that I don't have all of the necessary knowledge...I'm here to learn. That's why I'm asking the question on this forum.

  5. Sep 8, 2012 #4

    Vanadium 50

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    And like Ben said, nobody will sell you a source like that. So we're done here.
  6. Sep 8, 2012 #5


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    To elaborate a bit on "nobody's going to sell you such a source"...

    In order to buy a strong-enough source for your purposes legally, from a legitimate vendor, you need a license from state and/or federal regulatory authorities (assuming you're in the U.S.). Here in South Carolina, for example, the relevant agency is the state Department of Health and Environmental Control (DHEC). You have to convince them that you have proper training in handling such sources, and that you have facilities to store them safely.
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