[ RadSafe ] Red Sand

Sun Mar 24 18:42:26 CDT 2013

Good Afternoon All,

Back in my days working in the old Rad Health Branch here in CA, radioactive
cleaning or blasting sand was a continual problem especially as more and
more radiation detectors came on line.  The clearest regulatory "hook" we
could find was if the material in question met the definition for source
material in the regulations.  Even then there were questions about
distribution (as in selling) and disposal that kept us and owners of said
sands in fits.  Don't know that we ever came up with a clear answer.  My
opinion is that these items should simply be exempt.  Any and all opinions
are welcome.

Victor

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Cowie, Michael I
Sent: Saturday, March 23, 2013 11:14 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Red Sand

Thanks Dan, but perhaps I was being a bit obtuse with information on my
earlier email. The material has been found spread over an area and appears
to have been used in an uncontrolled way in an abrasive blasting method. I
have discovered that this area was used to overhaul and refurbish a large
section of pipework, and included blasting/hydro testing. I have some
pictures of the sand (unfortunately cannot append on the list), and also
XRF/XRD analysis which indicates:

Si 20.9%
Fe 14.9%
Al 4.7%
Ca 3.7%
Mg 1.7%
Na 0.8%
Ti 0.7%
Mn 0.5%
K 0.4%
S 0.3%
Cl 0.1%
Zr 0.09%

Almandine-(Mg0.6Fe2.4)Al2(SiO4)3        47 Wt%
Quartz-SiO2                             44 Wt%
Calcite-CaCO3                           6 Wt%
Microcline-KAlSi3O8                     3 Wt%

Looking at the U figure in the data provided it gives 14.8 +/- 3.7 ug/g. The
Th iis 181.7 +/- 2.9 ug/g.

The material is definitely alien to the place where it has ended up, but not
yet been able to track down where it came from.

I also have a nice image of the spread of the contamination over the area
using the RadSurvey gamma mapping equipment.

Mike

-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Dan McCarn
Sent: Sunday, March 24, 2013 8:50 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Red Sand

Dear Michael:

I think it is highly unlikely to be garnet.

The described material is far more likely to be a red zircon sand, hard and
abrasive, and can be concentrated in beach and stream placers in & around
igneous and metamorphic terrains because it does not tend to weather. From
memory, it can contain up to about 1% uranium. Zircon is a zirconium
silicate for which the zircon can be replaced with a significant amount of
rare-earth elements including thorium as well as uranium.

For a zircon containing 0.25% U-nat, that would amount to an activity of
about 30 Bq/g for each member of the decay chain.  I have seen and mapped
Cretaceous beach placers in the Trinidad sandstone of Colorado / New Mexico
for many kilometers.  Undoubtedly, the beach sand was derived from the
ancestral Rockies, full of granite with abundant zircon.
 Long-shore drift concentrated the beach placers giving them a significantly
higher gamma "kick" with borehole-logging tools than would be expected, and
were occasionally mistaken for "roll-front" type sandstone uranium deposits,
but are of no economic interest (for uranium) due to the chemically inert
nature of zircon. Neither uranium nor thorium would leach from zircon sands.

See http://en.wikipedia.org/wiki/Zircon

"Zircon occurs in many colors, including red, pink, brown, yellow, hazel, or
black. It can also be colorless. The color of zircons can sometimes be
changed by heat treatment. Depending on the amount of heat applied,
colorless, blue, or golden-yellow zircons can be made. In geological
settings, the development of pink, red, and purple zircon occurs after
hundreds of millions of years, if the crystal has sufficient trace elements
to produce color centers. Color in this red or pink series is annealed in
geological conditions above the temperature about 350 °C."

"Zircon is a common accessory to trace mineral constituent of most
granite<http://en.wikipedia.org/wiki/Granite>
 and felsic <http://en.wikipedia.org/wiki/Felsic> igneous rocks. Due to its
hardness, durability and chemical inertness, zircon persists in sedimentary
deposits and is a common constituent of most sands. Zircon is rare within
mafic rocks <http://en.wikipedia.org/wiki/Mafic_rock> and very rare within
ultramafic <http://en.wikipedia.org/wiki/Ultramafic> rocks aside from a
group of ultrapotassic intrusive
rocks<http://en.wikipedia.org/wiki/Ultrapotassic_igneous_rocks> such as
kimberlites <http://en.wikipedia.org/wiki/Kimberlite>, carbonatites, and
lamprophyre, where zircon can occasionally be found as a trace mineral owing
to the unusual magma genesis of these rocks."

"Zircon forms economic concentrations within heavy mineral sands ore
deposits <http://en.wikipedia.org/wiki/Heavy_mineral_sands_ore_deposits>,
within certain pegmatites <http://en.wikipedia.org/wiki/Pegmatite>, and
within some rare alkaline volcanic rocks, for example the Toongi Trachyte,
Dubbo, New South Wales
Australia[9]<http://en.wikipedia.org/wiki/Zircon#cite_note-9> in association
with the zirconium-hafnium minerals
eudialyte<http://en.wikipedia.org/wiki/Eudialyte> and armstrongite."

Dan ii

Dan W McCarn, Geologist
108 Sherwood Blvd
Los Alamos, NM 87544-3425
+1-505-672-2014 (Home – New Mexico)
+1-505-670-8123 (Mobile - New Mexico)
HotGreenChile at gmail.com (Private email) HotGreenChile at gmail dot com

On Sat, Mar 23, 2013 at 10:51 PM, Cowie, Michael I <michael.cowie at aramco.com
> wrote:

> Abrasive Sand/grit
>
> Also recently encountered some red coloured fine sand, it has been
> suggested the material is "Garnet". Activity concentration is in the
> order of 30Bq/g (Total activity), and have measured gamma dose rates
> of in excess of 3microSiverts/hr from the material. A few years ago we
> ceased using abrasive sands/silica for blasting/preparation ops due to
> health related issues (silicosis) and the replacement material is a
> type of black grit (a trade name I have seen is EuroGrit, but there
> are others). This also has slightly enhanced activity levels but only
> around 1Bq/g. So it came as a bit of a shock to find this material,
> particularly with such enhanced activity levels and associated gamma
dose-rate.
>
> Again a couple of questions:
>
> Are the activity concentrations in the "granet" or Rad Sand typical?
> Are there standards to which suppliers should adhere?
>
> I am pretty certain that this material if shipped now would trigger
> alarms at ports of entry if exported.
>
> Mike
>
>
>
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