This article is about elevated levels of Lead-210 left over from WWII sources that has contaminated a school. I don’t recall hearing of this isotope before. What nuclear weapons manufacturing would have produced it?
See
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Specifically, this:
Florissant (where this school is located) is not very near to Weldon Spring (where I actually went to elementary school for awhile).
I believe the relevant source is actually contamination of Coldwater Creek, which was likely caused by a Mallinckrodt factory that produced weapons-grade uranium for DOE. That factory was north of the airport, for those familiar with St. Louis geography.
As to why Lead-210 in particular, I haven’t found a useful explanation. It seems to be a very rare isotope. But it does have a 22-year half-life which could explain why it’s still around in measurable quantities.
The two most common radioactive decay modes either leave the total number of nucleons unchanged (beta decay), or decrease the total number of nucleons by 4 (alpha decay). So all of the heavy elements can be sorted into four main categories, based on their number of nucleons modulo 4. Lead-210 is two more than a multiple of four, so it’d come from other elements that are two more than a multiple of four. Uranium-238 comes to mind, though the first step on that one is slow enough that it probably doesn’t lead to a lot of lead-210.
The report (linked from the CNN article) notes that there’s concern about thorium-230 and radium-226 at the same site as well, which are part of the same decay chain.
It wouldn’t surprise me if uranium refining leads to a high concentration of radioactive daughter nuclei in the “slag” that’s left behind. But I don’t know enough about the chemical processes involved to say more than that.
That was what I came here to say. If you have a sample of u-238, it’s going to be a very long while before it builds up daughter products enough to be hazardous. But, if that u-238 was in the ground for a couple billion years, then a substantial part of it would have decayed, and those daughter products would be left behind in refining.
I suppose that makes sense: Start with a lot of uranium ore, containing mostly uranium but also trace amounts of all of its descendant isotopes. Refine out all the uranium, and dump everything else all in the same place.
uranium ore is refined at the uranium mines to make it “yellow cake”, uranium oxide.
It then has to be reduced to make it uranium metal.
well when its a metal and you have a vat of molten uranium, the slag would be high in lead …which has mostly come from fission chain, so its lead high in the radioactive isotope.
There is the possibility that they are taking the level of radioactive lead as warning that there may hidden dangers, stuff they didnt test for , but more toxic in its very very tiny levels… like those iodine and caesium isotopes…
But in this case, the toxin is lead, pure lead. The risk of cancer is really to do with the level of radiation vs expected background radiation, because the lead has come from refining metallic uranium, which means it very high in lead… the chain was complete… it was uranium ore, which means it had been fissioning , turning to lead, for billions of years. low levels of the other decay chain…
They could be mixing up standards for reactor waste with uranium ore processing waste … or a using a standard for proving there is no nuclear industry waste in the area … and when it fails that test, they say that there is dangerous level of nuclear industry waste… ??? the signature is just lead, because that is high in yellowcake, lead oxide being the main contanimation in yellow cake, which was precipated uranium oxide… lead oxide precipitating with the uranium oxide.
If it were just lead that was a problem, through ordinary chemical heavy-metal toxicity, then they’d be more concerned about the far more abundant (but stable) lead-206 (which is the actual end of that decay chain, three steps after the lead-210).
And fortunately, “radiation toxicity” is very easy to test for, with a Geiger counter or similar device. If there’s enough radioactive iodine or cesium or whatever to be bad for health, then it’ll also be enough that you’ll get clicks from it.
Reading the report, the contaminant they are worried about is radioactive thorium.
The reference to lead is the uranium to lead fission chain… The slag contains Thorium Phosphate and a lower level of some other phosphate salts, by the looks of it. This slag is in the creek, and floods from the creek drops a layer of mud on the grounds of the school, houses, streets,parks, etc, so each flood will put the slag on the ground …
The recommendation is that the soils return to normal, but it is a concern that children in the area would receive higher than normal doses of radiation , if a flood puts these radioactive particles into their homes, schools, child care facility, parks, sidewalks… then its everywhere they go, so they are constantly exposed to the higher radioactivity.
While they can check the radioactivity of the soil around the school , and the suburb, is only slightly above background at the moment, they cannot say what will be after the next flood, and the Coldwater creek should be treated as a danger until remediated …
See if there is a dry spell after a flood, the mud from the flood could turn to dust and be inhaled, and the thorium particles, tangible as a grain of sand, of 70% thorium, could be collected in the lungs … so its rather dangerous but not actually there at the moment. Its a warning that it could be a problem.