Grand Canyon tourists exposed for years to radiation in museum building, safety manag

crescent

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crescent
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Grand Canyon tourists exposed for years to radiation in museum building, safety manager says

For nearly two decades at the Grand Canyon in Arizona, tourists, employees, and children on tours passed by three paint buckets stored in the National Park's museum collection building, unaware that they were being exposed to radiation.

Although federal officials learned last year that the five-gallon containers were brimming with uranium ore, then removed the radioactive specimens, the park's safety director alleges nothing was done to warn park workers or the public that they might have been exposed to unsafe levels of radiation.
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Three buckets of uranium ore stored in the building.

The report indicated radiation levels at 13.9 millirems per hour where the buckets were stored, and 800 per hour on contact with the ore. Just five feet from the buckets, there was a zero reading.
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Belz... said:
Uranium ore? Isn't that harmless alpha radiation?
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No idea - that why I posted it here. I couldn't tell if this was a real thing for people to worry about, or just an ill-informed freak out about radiation where little actual risk exists.

I was also wondering about the radon that the ore may have emitted. That might have been the greatest risk to people who spend long hours working in the building.
 
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crescent said:
No idea - that why I posted it here. I couldn't tell if this was a real thing for people to worry about, or just an ill-informed freak out about radiation where little actual risk exists.
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Far as I know, U238 only emits alpha particles, and those can't get past your skin. I wouldn't worry.
 
Relevant xkcd

I'm not too concerned about the tourists passing through. I'm worried about the museum workers who were getting regular doses over several months/years.

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It's helpful to understand that there's a *huge* interval between "normal backround radiation" and "dangerous levels of radiation". The reason we worry about levels of radiation above normal backround but below dangerous levels is because they indicate a potential problem somewhere. E.g., a leaking reactor. San Onofre never leaked enough to cause any harm or even risk to the public, but the fact that it was leaking at all was a serious problem.
 
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Belz... said:
Far as I know, U238 only emits alpha particles, and those can't get past your skin. I wouldn't worry.
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If it's ore, then it probably isn't depleted, and so should contain some U235 as well.

But probably still not a huge risk, if you're not huffing the dust.
 
The ore was stored in paint buckets. How old were the buckets? Any Lead residue to counteract the radiation?

"Lead paint! Delicious but deadly!"
 
It's really dangerous if you cram enough of it into the same volume at the same time. Especially if you contrive to juice it with extra neutrons while you're cramming it together.
 
Let us all be thankful that the tourists weren't subjected to the giant electric thunderbolt that created the GC. According to a certain mythology-based cult :)
 
British trrops in Bosnia were barracked in a commandeered cannery. Unfortunately there were two radiation sources there that they didn't know about that were used to meause the metal thickness for making the cans. They only found out when two visiting Canadian soldiers had their dosimeters checked... Oops
 
Mikemcc said:
British trrops in Bosnia were barracked in a commandeered cannery. Unfortunately there were two radiation sources there that they didn't know about that were used to meause the metal thickness for making the cans. They only found out when two visiting Canadian soldiers had their dosimeters checked... Oops
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What oops? Also your story got badly garbled for a few important words in the middle.
 
If it was uranium ore, then it had to be like 99% U-238 which decays via beta and alpha decay to lead over millions of years. The thorium and polonium beta decays are probably the highest contributors to the radiation levels due to their much shorter half lives.

Most betas, depending upon energy level, are attenuated by air within two meters. This would account for the low radiation level at five feet from the storage location given an 800 mr/hr on contact reading.

Alpha is normally only a hazard when the isotope is inhaled or ingested.
 
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It sounds as if it was unenriched ore (all natural, right?) and it really represented a very modest exposure even if one looked down from a few feet onto the top of the bucket. About the level one would pick up from a round trip long airline flight. Much much less than most single CAT scans. And that is standing close and looking at the exposed ore. As noted upthread alphas don't even penetrate skin let alone metal bucket walls (lead or steel)' they are dangerous only if ingested or breathed in and I doubt anyone was stirring the bucket to make dust. Betas are a little more complex: they are quickly attenuated by air and distance and easily screened by wood, plastic, etc. but very strong energy betas convert to gamma rays when they hit thin metals. The fact there was essentially zero exposure beyond 5 feet suggest this was not going on in this case. Thick wall buckets probably (which screen the gamma rays).

I agree with removing the ore (or placing it behind leaded plastic/glass shields). Why not play it safe (and also not frighten people) even though I don't see it as a real risk to the visitors compared to all the other low level radiation people are exposed to in all the rest of their lives. But the implication that people "exposed" to the uranium should now be tracked down and told about it is ridiculous, given (a) there is nothing that it would actually have done to them, (b) you would be scaring the crap out of those who will now worry that they will die of cancer or turn into a horrible mutant, a real and unnecessary negative effect and (c) there is nothing they can actually do about it now.

My comments are focused on the visitors; if there were workers who spent long times very close to the ore: that may have added up to a significant exposure.
 
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What bugs me about the reporting on this story is the phrasing about "safe limits". For example:

By his calculation, those children could have received radiation dosages in excess of federal safety standards within three seconds, and adults could have suffered dangerous exposure in less than a half-minute.​

Well, no. The NRC safety limits are limits where we have high confidence that amounts below the limit are safe. They are not limits where it's automatically dangerous if you're above the limit. Chances are it's still safe even a fair amount above those limits.

But there's even more to it. The limits for the general public are different than the limits for radiation workers. This isn't because radiation workers are somehow more radiation resistant than the general public, and it's not because radiation workers are less important than the general public. It's because it's practical to set the limits for the general public much lower, and something's wrong with what you're doing if you're exposing the general public to the same levels as radiation workers, even if it's not dangerous to them.

tl;dr: just because an exposure level exceeded the NRC limits doesn't mean it's dangerous.
 
This is a scare story.

The idiot claimed crap like this:

"Stephenson said any radiation contamination that reached the exhibits may have caused harmful exposure to children within seconds, and adults within a half-minute."

Complete and utter nonsense.

Then he noted that detectable radiation was zero 5' away. That pretty much says the radiation detected was Alpha and probably some Beta, but the Alpha is what would have kicked the meter into high gear.

Reminds me of the dust brushes containing Po210 I used to buy at Fedco for $15 or so. The things would peg my GM meter on the least sensitive scale (200 mr/hr) and did so for 2 years after I bought them. Which means that at the time I bought them the registered dosage rate would have been about 100 times higher or > 20 rem/hr.

Of course, being an Alpha emitter, 2" away from the brush nothing was detectable above background.

Now U ore contains mostly U238 with some U235. They would also have a mix of decay products, decaying in equilibrium (decays at approx. the same for each daughter) which were also releasing mostly Alpha and Beta and some Gamma.

Gamma would have been at least detectable 5' away if the stuff was materially dangerous. The danger from Alpha is purely if it's released internally in which case it is very dangerous. But outside the body, it's insignificant at even high levels. Beta is more dangerous but only slightly. It's attenuated in air and mostly on the first dead layer of skin.

The brushes were quite good at eliminating static. Interestingly, the Alpha was so strong that it would make the fluorescent ink on my wall poster glow in a darkened room when held against it.
 
marting said:
This is a scare story.

The idiot claimed crap like this:

"Stephenson said any radiation contamination that reached the exhibits may have caused harmful exposure to children within seconds, and adults within a half-minute."

Complete and utter nonsense.

Then he noted that detectable radiation was zero 5' away. That pretty much says the radiation detected was Alpha and probably some Beta, but the Alpha is what would have kicked the meter into high gear.

Reminds me of the dust brushes containing Po210 I used to buy at Fedco for $15 or so. The things would peg my GM meter on the least sensitive scale (200 mr/hr) and did so for 2 years after I bought them. Which means that at the time I bought them the registered dosage rate would have been about 100 times higher or > 20 rem/hr.

Of course, being an Alpha emitter, 2" away from the brush nothing was detectable above background.

Now U ore contains mostly U238 with some U235. They would also have a mix of decay products, decaying in equilibrium (decays at approx. the same for each daughter) which were also releasing mostly Alpha and Beta and some Gamma.

Gamma would have been at least detectable 5' away if the stuff was materially dangerous. The danger from Alpha is purely if it's released internally in which case it is very dangerous. But outside the body, it's insignificant at even high levels. Beta is more dangerous but only slightly. It's attenuated in air and mostly on the first dead layer of skin.

The brushes were quite good at eliminating static. Interestingly, the Alpha was so strong that it would make the fluorescent ink on my wall poster glow in a darkened room when held against it.
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I had one of those. They were fabulous for dusting photo negatives! I was a bit leery of it because it was a powerful emitter, but as you stated I concluded it was quite safe if stored and used properly and the isotope remained well immobilized on the brush.

The business about harm to children or adults at the exhibits from some unenriched uranium ore is absolutely -boggling stupid crap! How can such alarmist drool pass for news?
 
Giordano said:
The business about harm to children or adults at the exhibits from some unenriched uranium ore is absolutely -boggling stupid crap! How can such alarmist drool pass for news?
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The anti-nuke lobby grabbed the rhetorical high ground two generations ago, and their fearmongering has driven mainstream perceptions of nuclear power and atomic radiation ever since.

It passes for news because journalists are just regular people, formed by the same urban legends and conventional wisdom as everyone else. It's not like they're going to know any better than the guy who called out the "harm" in the first place.
 
theprestige said:
The anti-nuke lobby grabbed the rhetorical high ground two generations ago, and their fearmongering has driven mainstream perceptions of nuclear power and atomic radiation ever since.

It passes for news because journalists are just regular people, formed by the same urban legends and conventional wisdom as everyone else. It's not like they're going to know any better than the guy who called out the "harm" in the first place.
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The Park's Safety Manager was the "whistle blower," claiming that the higher ups didn't want to warn the public about the, in his mind, dangerous exposure. I would expect the Safety Manager would have bothered to inform himself or at least his bosses would have seen to a bit of education about the actual, non-existent, "hazards."
 
Background radiation levels outside the building 2.02 mrem/hour

Inside the building 1.85 mrem/hour

Stay inside every one.

They could have got those doses if they hugged the buckets of natural ore.

You don't estimate whole body doses from contact readings like the safety officer did.

Or you might have a problem if you tried to extract the radium from the ore in your wedding dress.
 
I would have thought the cheapest and best solution would be to take the buckets out and dump the sand in the parking lot. If they can't find better sand in the back yard, go down to Home Depot and buy a bag.
 
marting said:
The Park's Safety Manager was the "whistle blower," claiming that the higher ups didn't want to warn the public about the, in his mind, dangerous exposure. I would expect the Safety Manager would have bothered to inform himself or at least his bosses would have seen to a bit of education about the actual, non-existent, "hazards."
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You would think wrong, then, because that's obviously not what happened.
 
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theprestige said:
You would think wrong, then, because that's obviously not what happened.
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Yes. Pathetic. Now the thing is on the news widely w/o the least bit of competent science. Really, there's a lot of informed sources they could have checked with.

Even highly concentrate DU or just regular U is pretty innocuous, let alone ore. DU was used for all sorts of things, boat keels, airliner counterweights and such because of it's high density. Widely used as shielding (mechanical) in large amounts on tanks because of its high density. And U is not exactly an uncommon element. It's pretty ubiquitous in lots of places.
 
I've used it in a trebuchet counterweight.

I also note there's only concern for the tourists, who might visit once or twice in a lifetime. What about the employees?
 
Trebuchet said:
I've used it in a trebuchet counterweight.

I also note there's only concern for the tourists, who might visit once or twice in a lifetime. What about the employees?
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Concern for the employees is expressed both in the original article, and in this thread..

But I do have a theory about why the headline is about tourists.
 
It also doesn't say what grade of ore.

If if it was pitchblende, crystals of Uranium oxide, it may be pretty easy to find in the area

from wikipedia

In the United States, it can be found in the states of Arizona, Colorado, Connecticut, Maine, New Hampshire, New Mexico, North Carolina and Wyoming.

They took the ore and dumped it in an abandoned copper and uranium mine about a mile or two away, the orphan copper mine.
 
marting said:
Yes. Pathetic. Now the thing is on the news widely w/o the least bit of competent science. Really, there's a lot of informed sources they could have checked with.

Even highly concentrate DU or just regular U is pretty innocuous, let alone ore. DU was used for all sorts of things, boat keels, airliner counterweights and such because of it's high density. Widely used as shielding (mechanical) in large amounts on tanks because of its high density. And U is not exactly an uncommon element. It's pretty ubiquitous in lots of places.
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It's actually very incommon by mass, but yeah, it's pretty much everywhere.
 
Belz... said:
It's actually very incommon by mass, but yeah, it's pretty much everywhere.
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All a matter of degree. U is more common (percentage by weight) than Hg and about on the order of Tin, Arsenic, Iodine, and many other elements.

It was widely used until WWII when most U, which was largely considered an excess waste product from other mining operations, was quietly scarfed up as the significance of fission energy yield got noticed. Subsequent DU (99.8% U238) was then used as it was an enrichment waste product.
 
Finally, some sanity even if the reporting confused Gamma and Alpha. Geez, isn't this stuff taught in every high school physics class?

https://www.azcentral.com/story/new...r-warning-elston-swede-stephenson/2923344002/

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Little and Modi Wetzler, a chemistry professor at Clemson University who studies nuclear waste, said there are three types of radiation, and uranium ore emits only the least-dangerous rays, comprising gamma particles.

Wetzler said gamma rays are hazardous if inhaled or swallowed, but not externally dangerous because they can be absorbed and rendered harmless by a sheet of paper, a few inches of air, or a person’s outer layer of dead skin.

“The safety manager doesn’t know what he’s talking about,” Wetzler said. “Uranium ore would have a (radiation) value of zero. Either that, or it’s not ore and there’s some communication problem.”
 
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