[ RadSafe ] Re: uranium smoke is a teratogen

[Dan W McCarn]

Hi Mike:

I'm a little confused by your statement; Please correct me if I am wrong.

I recall that several countries have in the past been interested in the
economic recovery of uranium from uraniferous lignites (e.g. Wyoming Basins
- Great Divide Basin; Greece, etc.) because of the tendency of uranium to
remain in the ash. These resources tend to average about 100 mg/kg or 0.01%
U. The proposed recovery methods focused on combusting the material on a
fluidized bed, gasifying, and then burning the gas.  The uranium then tends
not to form a relatively unleachable ceramic, but can be easily leached from
the bottom/top ash.  In essence, the bulk of the uranium concentrates in the
ash.  This was the rage in the late 70s and early 80s in the consideration
of these special resources.

Since I have not seen the paper that you mention, I'm uncertain of its
veracity. If it assumes that all of the uranium contained in coal is
dispersed through the stack to fit someone's very simplified "mass balance"
concepts, this is patently wrong. The fluidized-bed technology was proposed
in order to take advantage of the fact that uranium concentrated in ash, to
get away from the ceramics formed at higher temperatures and to be able to
utilize high-uranium lignites. 

There were several papers about this in the early 80s through the IAEA
including Symposium Proceedings, TECDOCs, and as I recall, Technical
Cooperation missions from the IAEA to pursue this technology.

This is my recollection of one little "corner" of possible uranium recovery
strategies.


Other Sources: (These are back of the envelope calculations)

But there are other sources of anthropogenic uranyl ion in the environment.
As a rough estimate, for instance, the San Luis Valley, Colorado uses about
1 million acre feet of water for crop irrigation. By my estimate, 1,273.8 x
10^6 m^3 H2O, or 1.3 x 10^12 liters based on consumptive water use +
irrigation efficiency + off season irrigation (McCarn, 2004, IAEA TECDOC
1396, p. 303,
http://www-pub.iaea.org/MTCD/publications/PDF/te_1396_web.pdf).  The U
concentration ranges from <1 to over 100 ug/L with an average of perhaps
5-10 ug/L.  This amounts to a total of 7.5 Tonnes U / annum being
remobilized via irrigation.  Perhaps 10%, 0.75 Tonnes is immediately "lost"
to evaporation of droplets forming dispersed dusts downwind of the
irrigation.  If this accounts for 1% of the central-pivot, spray-irrigated
farming in the USA, then about 75 Tonnes of airborne uranium per annum are
being generated only by irrigation. 

As a side note, that also amounts to 2-3 KCi / year 222Rn redistribution for
the San Luis Valley, Colorado (Kilo Curies).

The Central Valley in California has many water use / quality similarities
of the San Luis Valley in Colorado including zones in which uranium is
concentrated and remobilized via high-volume pumping of the aquifer.  I
suspect that most of the intermontaine basins in the mountain west have
similar characteristics.  The old high-plains Ogallala aquifer, almost
depleted now from Texas to the Dakotas, contained significant uranium as
well.

Another source are fertilizers (phosphate ores contain about 125 mg/kg U or
0.125% U) which is contained in the product. About 5,000,000 Tonnes of
phosphate are used every year (USDA
http://www.ers.usda.gov/Data/FertilizerUse/).  That amounts to over 600
Tonnes of uranium being distributed on crops every year.  Some, perhaps 10%,
will be redistributed as dusts, adding another 60 Tonnes U per year to
airborne uranyl.

So for agriculture in the USA, I would "guess" that there are on the order
of 700 Tonnes U per year placed on agricultural soils and of that, 100
Tonnes U per year redistributed as dusts. Now "apply" the years of
agricultural use for the soils (e.g. 99 years - median - for the San Luis
Valley), a source term, a "Leaching Coefficient" to calculate the U
concentration in the upper soil zone, and transfer coefficients into plants,
etc. and now uranyl becomes an issue in the food chain.

So coal isn't the only "culprit".

Dan ii

P.S. And Mike, by my calculations based on Iran's import of Moroccan
phosphate ore, they can produce about 50-75 Tonnes U / year just from this
single source (90% recovery, DEPA-TOPO Solvent Extraction method,
wet-process phosphoric acid).

Dan W. McCarn, Geologist; 3118 Pebble Lake Drive; Sugar Land, TX 77479; USA;
Home: +1-281-903-7667 
mccarn at unileoben.ac.at           HotGreenChile at gmail.com          
UConcentrate at gmail.com


-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of Brennan, Mike (DOH)
Sent: Thursday, May 08, 2008 12:30 PM
To: radsafelist
Subject: RE: [ RadSafe ] Re: uranium smoke is a teratogen

Hi, James.

For coal fired power plants, I don't believe the vapor pressures of the
various uranium compounds are a controlling factor.  The uranium molecules,
in whatever oxidation state, would be entrained in the exhaust gases and
ejected into the atmosphere from a system designed to disperse all material
leaving the stack.  In "cleaner" coal fired power plants where substantial
amounts of particulate is scrubbed out of the exhaust, it is likely that
some percentage of the uranium will also be removed.  I would expect it to
be at least as available for resuspension as DU combustion products.

"Only about 8 tons of uranium per year in the U.S. is released in airborne
coal ash..."  James, misrepresentations like this are a fair part of why you
have less credibility than you might like.  The relevant quote from the
article you linked to is: "For the year 1982, assuming coal contains uranium
and thorium concentrations of 1.3 ppm and 3.2 ppm, respectively, each
typical plant released 5.2 tons of uranium (containing 74 pounds of
uranium-235) and 12.8 tons of thorium that year. Total U.S. releases in 1982
(from 154 typical plants) amounted to 801 tons of uranium (containing 11,371
pounds of uranium-235) and 1971 tons of thorium. These figures account for
only 74% of releases from combustion of coal from all sources. Releases in
1982 from worldwide combustion of 2800 million tons of coal totaled 3640
tons of uranium (containing 51,700 pounds of uranium-235) and 8960 tons of
thorium."  You chose numbers from a couple of decades ago rather than using
newer numbers from the graph, you use the US numbers rather than the much,
much larger world numbers, even though we are talking bout a world wide
issue, and you seem to have applied a 99% discount rate, presumably to
account for particulate precipitators removing fly ash, even though there is
no indication that the authors have not already taken that into account.
NOTE: I can not say for certain that they did, but I see several pieces of
evidence (the lines on the graph being represented as smoke from a stack,
for example) that the numbers they give are for airborne releases.  Further,
for the "world" numbers, it is known that many plants overseas do not have
as effective controls on particulate as do US plants.

>However, coal plant smoke is responsible for most of the uranyl in the
atmosphere right now, and most of the uranyl that has been breathed; but not
any of the largest acute or chronic human exposures.

OK, now we are getting somewhere.  I agree that coal smoke is responsible
for most of the uranyl (indeed, uranium in any form) in the atmosphere right
now, and for most of the uranyl that has been breathed.  I am not sure I
accept that there are not large acute exposure to people downwind of some of
the worst offenders in foreign countries, though I readily accept that for
those people uranium is not the highest health risk they are facing.  I
reject the idea that there are no chronic human exposures.  I would contend
that for you to argue that in the "chronic" exposure range DU is more of a
problem than coal smoke you must reject the Linear-No-Threshold/Population
Dose model, in which case you probably have at least some number for
exposure below which you believe it is not of concern.

>If you do a Google News search on [depleted.uranium birth.defects] you will
see that the Iranian press is more interested in the issue than the U.S.
press.

I believe the Iranian press is more interested in no small part because the
Iranian Government believes this is a topic in which they can incite
anti-American feelings, and that the truth content is of relatively little
concern.  I also believe that the Iranian Government, which sent out human
waves to clear mines and absorb bullet so their soldiers could attack Iraqi
fortifications would not hesitate to make and use DU projectiles, once they
had a bunch of depleted uranium sitting around.  

>What more can one person do?

Be more interested in truth than advancing a political agenda.  Guard one's
credibility by arguing fairly. 

>I am not affiliated with any "anti-DU forces."

Perhaps you should give it a try.  You could become a voice of reason.

-----Original Message-----
From: jsalsman at gmail.com [mailto:jsalsman at gmail.com] On Behalf Of Ben Fore
Sent: Tuesday, May 06, 2008 7:48 PM
To: Brennan, Mike (DOH)
Cc: radsafelist
Subject: Re: [ RadSafe ] Re: uranium smoke is a teratogen

Mike,

Thank you for your good questions:

Mike Brennan wrote: "So does this mean that a coal fired power plant,
especially one with inadequate exhaust scrubbing (as I believe describe most
of those in China), which burns coal that has uranium in it (as most coal
does, to one extent or another) is releasing uranium smoke with the uranium
in the +6 oxidation state?  Considering that there are a huge number of coal
fired power plants, and their fires and uranium smoke production is ongoing,
and the exposed population is truly huge, isn't this a far more important
exposure concern than DU projectiles?  And if you say it isn't, where is
your proof that it isn't?  (No reasoned arguments here: it has to be proof
that Chinese uranium smoke isn't as bad as American uranium smoke)."

Coal fired plants do release uranium in the +6 oxidation state, but not
much. I can't give you exact numbers for China, but I do have numbers for
the U.S. Coal has uranium oxides (in the +4 oxidation
state) distributed uniformly, and it burns at under 1300 Kelvin, producing
very little U(VI). The vapor pressure of UO3 at 1250 K is only 1e-5 mbar, so
not much makes it airborne. Only about 8 tons of uranium per year in the
U.S. is released in airborne coal ash ("This uranium is released to the
atmosphere with the escaping fly ash, at about 1.0% of the original amount
[800 tons/year U.S.], according to NCRP data." --
http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html
)  A tiny fraction of that is uranyl; I would guess far less than 10%.
 And most of that, if it isn't scrubbed, weathers before being inhaled. So
how many coal plants are there in the U.S. pumping out that < 0.8 tons of
uranyl per year?

The difference between the airborne soluble uranyl concentration in coal
plant smoke spread out over the country and uranium smoke in the region
around a DU-against-metal firefight is a huge difference. When metalic
uranium particles burn in air, the temperature exceeds 2800 K (Mouradian and
Baker (1963). "Burning Temperatures of Uranium and Zirconium in Air".
Nuclear Science and Engineering 15: 388-394) which pushes the partial
pressure of the uranyl production into the majority of the combustion
product. At 2800 K, the vapor pressure of UO3 is a full atmosphere, 1000
mbar, or a hundred million times more volatile than at the burning
temperature of coal.

However, coal plant smoke is responsible for most of the uranyl in the
atmosphere right now, and most of the uranyl that has been breathed; but not
any of the largest acute or chronic human exposures.

Mike Brennan also wrote: "Also, Iran is enriching uranium for its civilian
power plant.  This means that soon Iran will have a substantial amount of
deplete uranium.  Iran boarders two countries occupied by a hostile power
with an army that has great superiority in armored vehicles.  It is only
reasonable to believe that Iran will soon start manufacturing DU weapons for
its own defense (indeed, it is not at all impossible they have already
started).  Wouldn't NOW be an excellent time for the anti-DU forces to start
bringing pressure to bear against Iran, to get them to promise to never make
or use DU weapons?  That way, if there is a war between the US and Iran,
only one side will be using them, and thus limit the damage they will do."

If you do a Google News search on [depleted.uranium birth.defects] you will
see that the Iranian press is more interested in the issue than the U.S.
press.  What more can one person do?  I am not affiliated with any "anti-DU
forces."

James Salsman, as Ben Fore

>  -----Original Message-----
>  From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On 
> Behalf Of Ben Fore
>  Sent: Tuesday, May 06, 2008 10:26 AM
>  To: radsafelist
>  Subject: [ RadSafe ] Re: uranium smoke is a teratogen
>
>  Dan,
>
>  Thank you for your helpful question:
>
>  > Since everyone on the planet has been exposed to natural  > 
> concentrations of uranyl ions, constantly, day after day after day for  
> > their entire lives, how exactly is this so different from a brief,
downwind exposure to smoke?
>
>  U(VI) weathers to U(IV), and the proportion of natural uranium in
world-wide average soil in soluble compounds in the +6 oxidation state is
less than 0.01%, is it not?
>
>  Whereas in uranium smoke, most of the uranium is soluble, and most of 
> it is in the +6 oxidation state; at least 1/3 dissolves into the 
> uranyl ion
>
>  > And at what distance? Since the smoke should follow the behavior of 
> a  > Gauss "puff", as opposed to a "plume", after a kilometer or so of  
> > diffusion the concentration is very low.
>
>  I have studied the aerosol dispersion papers in Health Physics and the
recent papers by R. Guilmette and M. Parkhurst.  There is no doubt that
someone in a typical 500 m downwind or 150 m vicinity of a 1 kg uranium fire
will be exposed to thousands of times as much uranyl as they usually get in
a month.
>
>  But what good would it be if we knew the exact dose?  We still have no
idea what the effect is on any mammal with a nine-month gestation period ten
years after such an exposure.
>
>  That's why I keep asking everyone to try and get people to find out,
please.
>
>  > Once the dust settles, infiltration of rainwater will move it 
> deeper  > into the soil column along with all the other nicely-behaving,
natural uranyl complexes.
>
>  Which soluble U(VI) complexes remain after weathering?  None.
>
>  Mattias Olsson wrote:
>
>  > The interesting post below reminded me about an old incident I've 
> been  > told about with radiation alarms being  set off by the smoke 
> from a  > Danish coal fired power plant. The detector was placed at 
> the  > Barsebäck NPP site in Sweden, apparently in the plume. Burning 
> stuff  > that has been dug up from the ground seems like a nice way to 
> spread  > uranium. Or did, before modern filter technology anyway.
>
>  Do you mean radiation alarms or uranyl alarms?  While coal-fired plants
make a huge contribution to the amount of uranyl in the atmosphere (though
not approaching being in the vicinity of 30 mm DU autocannon fire), they
have not increased soil concentration of uranium much above 1600 levels,
because U(VI) weathers to U(IV).
>
>  James Salsman
>
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