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In mining, the uranium
and its decay products buried deep in the earth are brought to
the surface, and the rock containing them is crushed into a fine
sand. After the uranium is chemically removed, the sand is stored
in huge reservoirs. These left-over piles of radioactive sand
are called "uranium tailings".
Uranium tailings contain
over a dozen radioactive materials which are all extremely harmful
to living things. The most important of these are thorium-230,
radium-226, radon-222 (radon gas) and the radon progeny, including
polonium-210.
If this radioactive sand is left on the surface
and allowed to dry out, it can blow in the wind and be deposited
on vegetation far away, entering the food chain. Or it can wash
into rivers and lakes and contaminate them.1
While the hazard per
gram of mill tailings is low relative to most other radioactive
wastes, the large volume and lack of regulations for their containment
have resulted in widespread environmental contamination. Moreover,
the half-lives of the principal radioactive components of mill
tailings, thorium-230 and radium-226 are long, being about 75,000
years and 1,600 years respectively. The most serious health
hazard associated with uranium mining is lung cancer due to inhaling
uranium decay products.
Uranium mill tailings contain radioactive
materials, notably radium-226, and heavy metals (e.g., manganese
and molybdenum) which can leach into groundwater. What happens
to tailings after the mining companies have left the site poses
an incredible headache for future generations.
Olympic
Dam Tailings
If the giant Olympic Dam mine is
allowed to completely mine out the deposit, South Australia will
host the largest pile of uranium tailings on earth.
REFERENCES
1. Uranium:
A Discussion Guide CCNR
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Ranger Tailings Dam
"And
as these tailings are left on the surface of the earth, they
are blown by the wind, they are washed by the rain into the
water systems, and they inevitably spread. Once the mining companies
close down, who is going to look after this material forever?
How does anyone, in fact, guard 200 million tons of radioactive
sand safely forever, and keep it out of the environment?"
Dr.
Gordon Edwards , CCNR
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