Demonology 101 update. (Phoenix A/Gryphon C)

[Naldru]

Well, of -course-.

Who else would be manic enough to even attempt to annoy a Fae? ;-]

Several people on this forum come to mind when you say that.

I know who sounds like the first volunteer...Go for it Naldru! Me and Llearch will wait for you behind this lead shield!

Why does everybody think that lead is such good protection.  If you're talking about radiation, depleted uranium is better, and any material  barrier has to have a certain amount of thickness to be effective.  When dealing with radiation, the best protection is distance, lots of distance.  (If dealing with fae, finding another planet sounds good.)

I try not to provoke anger in others.  However, judging by Demonology 101, it sounds like Angels would have the right approach:  trick somebody else into doing it and find another continent to hang around while it happens.

[llearch n'n'daCorna]

Why does everybody think that lead is such good protection.  If you're talking about radiation, depleted uranium is better, and any material  barrier has to have a certain amount of thickness to be effective.  When dealing with radiation, the best protection is distance, lots of distance.  (If dealing with fae, finding another planet sounds good.)

I try not to provoke anger in others.  However, judging by Demonology 101, it sounds like Angels would have the right approach:  trick somebody else into doing it and find another continent to hang around while it happens.

Lead is easier to get hold of in large quantities. That's about it.

[Naldru]

Lead is easier to get hold of in large quantities. That's about it.

True, especially because of the forms that you have to fill out to prove that you aren't purchasing the depleted uranium for use in munitions.  (The extra weight gives an extra kick to the bullets.)  However, pound for pound, water is easier to get hold of than either of them.

[AndersW]

Lead is easier to get hold of in large quantities. That's about it.

True, especially because of the forms that you have to fill out to prove that you aren't purchasing the depleted uranium for use in munitions.  (The extra weight gives an extra kick to the bullets.)  However, pound for pound, water is easier to get hold of than either of them.

Yes, but water tends to get everywhere, doesn't stay where you put it, and tends to evaporate.

[llearch n'n'daCorna]

Lead is easier to get hold of in large quantities. That's about it.

True, especially because of the forms that you have to fill out to prove that you aren't purchasing the depleted uranium for use in munitions.  (The extra weight gives an extra kick to the bullets.)  However, pound for pound, water is easier to get hold of than either of them.

One pound of uranium is much more difficult to get hold of than 1000 lb of lead. If we assume the same ratios for ease of obtain-ability (which is probably on the low side, but the numbers multiply out nicely, so we'll stick with what we've got) I'm presuming that 1000lb of lead is more effective, if also more cumbersome, than 1 lb of uranium(depleted, or otherwise).

I'm not sure that 1,000,000 lb of water is more effective than 1000 lb of lead. And the cumbersome issue starts to become effective somewhere in there, meaning that -using- 1m lb of water is not doable, whereas using 1k lb of lead -is-.


All this is fairly obvious, though, I thought. Perhaps I was wrong?

[Naldru]

Actually, uranium isn't all that rare.  It's been used for hundreds of years as a pigment for glass and ceramic glazes.  The United States actually has a few very large mountains of depleted uranium because getting a pound of weapons grade uranium (U-235) meant removing roughly a hundred pounds of depleted uranium (U-238).  My understanding was, that until some people starting using it for rifle ammunition, the government was selling it rather cheaply just to get rid of it.  For this reason, many of the protective aprons used by X-ray technicians used depleted uranium instead of lead.

Water has a few big advantages:  it is transparent, it can usually be found locally, and it can be pumped.  This means that all you have to do is build a really big swimming pool and fill it with rater.  You can then watch safely watch the radioactive material.  A final advantage is that the convection currents provide a very efficient means of heat transfer.  That's why spent fuel rods are stored in big swimming pools.

[llearch n'n'daCorna]

I wasn't under the impression it was -rare-.

I was under the impression it was restricted, in that the governments tended to look askance at anyone who asked for some.


Sorry if I didn't make that clear. If it's not that hard to get hold of, of course, some of my argument becomes null and void. In fact, much of it becomes irrelevant... ;-]


(I could also go into the "it might be a touch iffy to go using it for -some- sorts of radiation shielding because the radiation will break the U-238 down into U-235, and making a critical mass of that isn't as hard as you might think..." argument, but I don't know, off the top of my head, enough of physics to know whether X-rays are likely to be one of that sort, if you'd get enough change to make critical mass, and what critical mass is at STP, and the chances of uranium doing it's phase shifting thing on you accidentally... All I know is, it's not something to mess about with. :-] )

[SpottedKitty]

For this reason, many of the protective aprons used by X-ray technicians used depleted uranium instead of lead.

I'm not sure I'd like to wear one. Uranium is in the part of the Periodic Table where elements have no stable isotopes — they're all more or less radioactive. I know, with a half-life of several billion years, U-238 isn't very active, but the stuff's chemically poisonous as well: remember, it is a heavy metal. With these delightful properties, a little goes a long way in the "keepitawayfromme" factor.   

[SpottedKitty]

(I could also go into the "it might be a touch iffy to go using it for -some- sorts of radiation shielding because the radiation will break the U-238 down into U-235, and making a critical mass of that isn't as hard as you might think..." argument, but I don't know, off the top of my head, enough of physics to know whether X-rays are likely to be one of that sort,

No need to worry, X-rays don't do a thing to U-238.

It's neutron bombardment that does neat stuff to U-238 and transforms it.

Into plutonium...   

[candide]

No need to worry, X-rays don't do a thing to U-238.

Indeed.

And what you want, in terms of an apron for X-Raying, is a material that readily absorbs those frequencies of the electromagnetic spectrum, but either re-emit it at lower frequencies (i.e. engery), over a longer period of time, and/or convert it to phonons (read: internal heat).

I'd rather expect U238 to reemit x-rays rather readily.  But, I don't know its atomic states.  (They never taught that to us in grad-school, only the basic principles.    )

[Naldru]

I wouldn't be surprised if normal granite is more radioactive than depleted uranium (U238).  (My understanding is that radioactive breakdown of one of the minerals in granite is the main source of radon gas.)  Air is also measurably radioactive.  (The carbon in radioactive carbon dating comes from the carbon dioxide in the air.)

[SpottedKitty]

I wouldn't be surprised if normal granite is more radioactive than depleted uranium (U238).

[looks at granite walls of house]

[looks out window at granite buildings]

Well, erm, yes, I do happen to live in an area where most of the buildings are granite, and everything here does have a slightly higher than average background count, but I don't know how it compares to U-238.

[candide]

I wouldn't be surprised if normal granite is more radioactive than depleted uranium (U238).  (My understanding is that radioactive breakdown of one of the minerals in granite is the main source of radon gas.)

Exactly!  And the parent mineral producing that radon?

Uranium.  Specifically, U238. 

The professor that I did my undergrad thesis with told me the following:  Every mineral, every rock that someone's dug out of the depths of the Earth, has trace amounts of Uranium and Thorium in it and on it.  (He then said that we should, therefore, always wash our hands after touching the various minerals we'd been working with.)

Uranium and Thorium are quite common throughout the lithosphere and the mantle.  They are, it is proposed, what cause the Earth's interior to remain molten, due to their radioactive decay.  And since they undergo alpha decay, they're also the source of all Helium on this planet, too.

[Naldru]

I suspect that radon would come from the decay of U235, not U238.

[candide]

I suspect that radon would come from the decay of U235, not U238.

Oh, U238 does decay.  It just takes a very long time.

According to my e-periodic table ("kalzium", part of the KDE Linux desktop), the half-life of U238 is 4.4 billion years.  However, it's also 99.2% of all of the uranium out there.  The other isotopes are much, much rarer.

Now kids, a little science lesson:    "Half-life" is actually an average of a probability.  Saying, "A neutron has a half-life of 5 minutes," does not mean it'll sit there for 5 minutes, then go *poof* once "the clock runs out."    It means that there's a 50% chance it will undergo decay sometime in the next 5 minutes.  Or, if you prefer, if you have a lump-o-neutrons, there's a 100% chance that 50% of the neutrons in the lump will decay after 5 minutes.

I could go on. 

So, with a half-life of 4.4 billion years, a lump of U238 with 10 billion atoms in it is certain to see at least one atom decay into Thorium sometime within a year.  How many is 10 billion atoms?  A pile the size of a house?  Well, consider (kisses to my chemist-Sweetie for this info!) that 18 grams of water (a little over 3/5 of an ounce) contains 600,000 billion billion molecules of water.  10 billion U238 atoms would be .004 nanograms.

So, it should be obvious that, even with that über-long half-life, even a small grain of U238 will have quite a number of atoms of U238 radioactively decaying each second.

I also need to correct myself slightly.  Uranium doesn't decay directly into Radon.  Since it undegoes alpha-decay, its atomic number drops by 2.  So the actual decay path is Uranium->Thorium->Radium->Radon.  (Unless the Radium undergoes beta-decay instead of alpha-decay.  Hmmm... another possibility is that the alpha-decay destabilizes the nucleus and it fissions into different elements than what I've listed.  But, you peeps can easily look that up.  )


{ Edit:  I was actually playng a bit fast-n-loose with the numbers there.  If you really want to go from half-life to a decay rate, divide .7 by the half-life.  (Your decay rate will be in units of "N/year".)   You can then use the rate as a likelihood that a U238 will decay after 1 year, and from there, it's just get a large enough sample to see 1 atom decay per year. }

[Naldru]

I took a look at the web and came up with the following

U238 half-life 4.5 billion years
U235 half-life 700 million years
C14   half-life 5800 years
Pu238 (plutonium) half-life 88 years

So there probably is approximately the same number of disintegrations from the U235 and U238 atoms in natural ores, since the ores are slightly over 99% U238.  However, without knowing the decay patterns, it is difficult to tell how much radiation they would give off.

So I won't disagree with the idea that depleted uranium might give off some radiation.  However, if the depleted uranium apron stops 100 times as much ionizing radiation from the x-ray machine as it gives off itself, does it really make a difference?  Wat I'm saying is that you haave to look at how much radiation actually reaches living tissue to do damage.

Otherwise, we end up with the situations like the mercury scare with tuna some years ago.  It turned out that a new test for mercury had been developed that was sensitive enough to find the amount of mercury in tuna.  Since people claimed that there were no naturally occuring sources of mercury in tuna, the claim was that it was all from pollution.  After the scare started reaching ridiculous proportions, somebody went to a museum in Albany, New York and found some fish that had been taken by Henry Hudson in the Hudson River in the 1600's and early 1700's (This is the river that goes through New York City.) and found the exact same level of mercury.  Further research indicated that there was a natural source of mercury in fish.

People tend to be scared of the wrong things.  In many cases, they avoid safe activities because of perceived hazards and then engage in much more dangerous activities.

[superluser]

Actually, uranium isn't all that rare.  It's been used for hundreds of years as a pigment for glass and ceramic glazes.

Stay away from the red Fiestaware, kids!

That's why spent fuel rods are stored in big swimming pools.

Please tell me that they're stored in pools, and not swimming pools.

it might be a touch iffy to go using it for -some- sorts of radiation shielding because the radiation will break the U-238 down into U-235, and making a critical mass of that isn't as hard as you might think...

It would be difficult to get to critical mass.  Wikipedia says that you need 52 kg in a 17 cm sphere.  I should think that it would be very difficult to do that to a vest-shaped object.

[Naldru]

Actually, uranium isn't all that rare.  It's been used for hundreds of years as a pigment for glass and ceramic glazes.

Stay away from the red Fiestaware, kids!

That's why spent fuel rods are stored in big swimming pools.

Please tell me that they're stored in pools, and not swimming pools.

"Swimming pools" is a nickname for them.  Nobody actually goes swimming in them.

Actually, the uranium pigments are bright yellow and thorium produces a very deep black.  I'm not sure what was used in the reds.  I remember a few museums had samples of ceramics and glasses with uranium and thorium pigments and would hold geiger counters to them as a demonstration.

The only way to convert significant amounts of U238 to U235 would be to place it in an active nuclear reactor for a few months.  By that time, there were be so many other radioactive isotopes in the material that it would glow under water due to the Cherenkov effect.

[DarkAudit]

People tend to be scared of the wrong things.  In many cases, they avoid safe activities because of perceived hazards and then engage in much more dangerous activities.

Or they have the hazards perceived into them by personal injury attorneys and the insurance companies.

[llearch n'n'daCorna]

it might be a touch iffy to go using it for -some- sorts of radiation shielding because the radiation will break the U-238 down into U-235, and making a critical mass of that isn't as hard as you might think...

It would be difficult to get to critical mass.  Wikipedia says that you need 52 kg in a 17 cm sphere.  I should think that it would be very difficult to do that to a vest-shaped object.

That -does- make it slightly difficult. ;-]

I was under the impression that Uranium changed density under different temperatures and pressures in a number of interesting ways likely to cause some accidental activity, if you stored it wrong... but I may be thinking of something else.


Also, I trust Wikipedia as a search mechanism, not as a final source. Particularly over anything that involves any subject that the populous finds interesting and/or scary. After hearing about subjects where professors in the subject had changes to Wikipedia removed by random Joes, I take Wikipedia with a grain of salt...

[Zedd]

Can someone get back on task or cubi gonna choke a box?

[mk1221]

Wasn't this supposed to be about Demonology?

How in the world did you get from Demonology to Uranium?

[llearch n'n'daCorna]

via X-rays, of course.

[Zedd]

via X-rays, of course.

Thats it..Im gonna shove your xrays straight up yo-Wait..Where you shove things up a box?

[llearch n'n'daCorna]

In Soviet Russia, box shoves things up you.

[Naldru]

In Soviet Russia, box shoves things up you.

Of course, if your're talking about the Luggage in the Discworld series, the box swallows you whole.

Have you ever heard of cow-chip bingo.  You mark a field into squares and everybody purchases a square and a cow is left to wander the field.  Where the chip falls, the owner of that patch of land is the winner.  Sometimes, I think that that is a good analogy to how discussions go in this forum.  They wander all over the place, with occasional pieces of unpleasant matter being left along the way.

[superluser]

"Swimming pools" is a nickname for them.  Nobody actually goes swimming in them.

I shoulda put a smiley on that.

Actually, the uranium pigments are bright yellow and thorium produces a very deep black.  I'm not sure what was used in the reds.

Uranium.  So says Hyperphysics.  Given the color of the red, it probably used the yellow pigment.

I was under the impression that Uranium changed density under different temperatures and pressures in a number of interesting ways likely to cause some accidental activity, if you stored it wrong... but I may be thinking of something else.

I'm not sure about that, but it's probably not going to happen from a vest.

Also, I trust Wikipedia as a search mechanism, not as a final source.

Meh.  Usually, I try to find more authoritative info, but when I'm arguing on the internet, I figure it's good enough until someone finds a real source.  That is also why I prefaced it with ``According to Wikipedia.''

[llearch n'n'daCorna]

Meh.  Usually, I try to find more authoritative info, but when I'm arguing on the internet, I figure it's good enough until someone finds a real source.  That is also why I prefaced it with ``According to Wikipedia.''

Heh. Granted, granted. ;-]

[Zedd]

Meh.  Usually, I try to find more authoritative info, but when I'm arguing on the internet, I figure it's good enough until someone finds a real source.  That is also why I prefaced it with ``According to Wikipedia.''

Heh. Granted, granted. ;-]

Yes...Bicker about your preesiouuss uranium...Makes you a nuclear god! Soon you will be a healthy green glow like Mr Burns

[Naldru]

Yes...Bicker about your preesiouuss uranium...Makes you a nuclear god! Soon you will be a healthy green glow like Mr Burns

Actually uranium, even fairly enriched uranium, is pretty safe to handle.  It's only after it's been in a reactor for a while that the decay products build up that it becomes really hazordous.  I don't think I've actually heard of anything turning green after being exposed to high radiation, unless you count The Hulk comic books.  It's actually more of a gray to black as necrosis and gangrene sets in.

When Wikipedia said that you need 52 kg in a 17 cm sphere, they were talking about very highly enriched uranium.  You could pile unenriched uranium in a mountain and nothing would happen.  (However, a few billion years ago, the percentage of U235 was high enough that you could obtain criticality with naturally occuring minerals.  No bangs, but a lot of high radiation for a while.)  When the Wikipedia and other sources talk about compressing the uranium, they are considering the use of high explosives to compress the mass.  No matter how much explosive you use, I don't think that you could get criticality using unenriched or depleted uranium.

Like gamma rays, nothing stops our topics from spreading all over.