docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jul 10, 2023 1:41:55 GMT -5
I have recently started a very small collection of radioactive minerals. I only have a couple of small specimens, uranophane and autunite. For safety reasons, I store them in the garage area (or was it the attic over the garage?) and i seem to have misplaced them. I could find them easily enough with a Geiger counter but I have no idea which radiation detector on Amazon would do the job best. I have had second thoughts about this new interest for sure, but really, in this unstable world, can you have too much fissile material? You can never tell when you might need to breed some plutonium. I grew up 6 miles from Oak Ridge, Tennessee, where my parents worked in the nuclear facilities, where fine handcrafted nuclear weapons were made. Nice town, in the middle of southern Appalachia, with more PhD's per capita than anywhere else in the world except Los Alamos, NM. No, I don't mean pentacostal hairdos. Seriously, my minerals are low grade stuff but some of these minerals are major gamma emitters and I don't feel comfortable with polonium and radon off-gassing. I can't find that much on how to best store these specimens, especially the higher activity minerals like uraninite that I might want. Just wondering if somebody out there can recommend an inexpensive radiation metering device or have any other advice or warnings to pass on. What constitutes adequate shielding as opposed to the 1.3 feet of lead needed to reduce emissions of gamma rays to a billionth of the original emissions. I just don't think I need to go that far.
Thanks! Mark H.
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Post by vegasjames on Jul 10, 2023 2:16:22 GMT -5
I keep mine, mainly carnotite (hydrated potassium uranyl vanadate) outside. May make some type of sealed case for some of the specimens at some point. I was thinking about maybe a leaded glass dome and put silicon carbide on the base and silicon carbide is an excellent radiation absorber. Back in high school I was with the Junior Academy of Science and we got invited to the American Nuclear Society convention. While there, I got a couple of samples of a new technology they were using to store highly radioactive waste. It was simply silicon carbide sandwiched with two sheets of aluminum. The plates wee only maybe 1/4" thick. I showed them to my physics teacher and we decided to test them. So we got out a particle counter and a very hot radioactive source. With just the source, the particle counter was flying. When one of the plates was placed between the radioactive source and the particle counter the clicks on the counter dropped to 1 to 2 clicks per second. Therefore, with the double walled containers they were making, all the radiation should have been contained. Here is an article on the subject. www.mindat.org/article.php/887/A+few+thoughts+on+the+safe+handling+of+radioactive+rock+specimens
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Post by vegasjames on Jul 10, 2023 2:51:43 GMT -5
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jul 10, 2023 11:30:10 GMT -5
I've read some threads/articles on Mindat.org already- love that site- and I realize my concerns may be overblown. I am a physician so I'm aware that the risks of radon and polonium exposure, which as I recall are alpha emitters, and risks are greatest from inhalation. Alpha and beta emissions aren't a big deal as far as shielding is concerned, but some of the materials I might want to collect are VERY hot and strong gamma emitters. The counts per second could be from ANY ionizing particle, and the counters don't distinguish alpha, beta, or gamma radiation. That leaves high gamma exposure as the least controllable problem. I am intrigued by the leaded acrylic sheets. I think they would be most suitable for X-ra shielding and that's probably heir main market. X-rays are of far lower penetrating energy than gamma rays. Old radiotherapy machines using a strong gamma source like cobalt 60 used several inches of lead. Using silicon carbide would be economical, but I question the ability of a 1/2" thickness to effectively shield from gamma rays. It might produce a drop in the counts per second in testing but the CPS are from what type of radiation? If it's alpha, ventilate the area but a piece of cardbord is sufficient shielding. Beta particles are stopped by a thin sheet of metal foil. However, they penetrate flesh readily. Magnetic and electrical fields are perfectly suitable to control beta emissions as they are just free electrons with a negative electrical charge (and used for some radiotherapy applications). I need to research the silicon carbide solution some more. I wish I could see a study where gamma emissions were being studied exclusively.
So, does anyone have a radiation meter that would work and doesn't cost hundreds of dollars? I have seen surplus civil defense Geiger Counters on ebay but they don't guarantee they'll work. They also need a weird and expensive "B" cell battery. They are basically from the early 1960s. Again, they may not discriminate gamma from other ionizing radiation.
Anybody else want to chime in?
G' day, Mark H.
P.S.- Found my autunite and uranophane specimens- right where I left them. Happy Happy Joy Joy! Mark
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Jul 18, 2023 2:05:04 GMT -5
I just read he mindat.prg article cited and found it very informative and reassuring. The author recognizes the inhalation of off-gassed alpha emitters as perhaps the most insidious problem and surprisingly, warns that radon can diffuse easily through many common materials like plastic films. He also does a good job of putting into perspective the actual radiation exposure one is likely to have from appropriate handling of properly stored materials. Overall, it's really well done. I have done a little reading on the SiC sheathing. It would stop alpha and beta which the above article regard as the major concerns anyway. It also is a fair neutron shield which would moderate slow fission in large masses of radioactive waste. neutron emissions aren't normally a health concern anyway. As for nuclear waste, most industrial radioisotopes are short-lived and constitute most nuclear aste. The hot stuff - spent fuel rods, for example, can be cast in a block of glass which contains them chemically. Add lead and you add some shielding as well. A typical nuclear power plant's waste after reprocessing, might occupy only a cubic meter or so. I'll have to ask a nuclear medicine colleague about handling of radioisotopes in the radiation oncology arena. Today, proton and electron beams, generated on site in what amounts to a particle accelerator/ atom smasher, have replaced gamma sources for many therapeutic applications. This means less shielding and no significant waste.
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