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Jim,
The uranium concentration in the McArthur River ore
is extraordinary (> 20% vs 0.1% in most uranium mines)! So I would
expect the gamma radiation level and the rate of radon emission to be much
higher than for most mines.
One of our senior radiation
biologists asked a miner recently what concerns he had
about exposures to radiation in uranium mines. He
said that he was much more concerned about big rocks falling down on
him. I expect that he is now concerned about flash floods too.
Special safety measures are in place to avoid
injuries to workers.
Jerry
----- Original Message -----
Sent: Saturday, May 17, 2003 2:35
PM
Subject: Re: [cdn-nucl-l] Water flows
into McArthur River uranium mine
Is this (underground processing) another case where "heroic"
and costly (and
double standard) measures are taken to reduce
"environmental impacts" in
nuclear applications that then also come back to
fail and add grotesque
costs and reinforce misperceptions of false
"dangers" of radiation and
nuclear technologies to the public?
Also
how does the "environmental impact saved" compare to coal mining
that
successfully prevents constraints on removing whole mountains and
dumping
them in valleys? (Or normal operation of a typical large
coal-fired power
plant?)
Regards, Jim
on 5/17/03 12:10 PM,
Jerry Cuttler at jerrycuttler@rogers.com
wrote:
> Recently this problem has been brought under control and
uranium mining may
> resume within several months.
> Jerry
>
---------------------------------------------------------
>
>
Water flows into McArthur River
> Nuclear Engineering
International - 17 May 2003
>
> Production has been
suspended at Cameco's McArthur River in Canada, the
> world's largest
high-grade uranium mine, because of flooding in the mine.
>
>
McArthur River was carved out of basement rock surrounded by porous
>
Athabasca sandstone. Water constantly flows in and is pumped out of
the
> mine, but a sophisticated refrigeration system is used to freeze
the
> surrounding ground and keep producing areas dry.
>
>
In an area where the freezing system was not yet installed, grouting
>
reinforcing concrete retaining walls were being carried out, and
rounding
> ground. Cracks were seen in the retaining walls, and the mine
was evacuated.
> Water began to gush into the tunnel on 6 April.
>
> The mine's pumps have been running around the clock, and additional
pumps
> have been brought in. Provincial and federal regulators have
been at the
> site, monitoring the flow of water into the mine and
surface treatment
> facilities. Water pumped from the mine contains
chemicals such as radium,
> and must be treated before it is placed into
settling ponds.
>
> Cameco president Gerald Grandey said the
situation was "critical" and the
> shutdown would last at least a couple
of months. In a later update, he said
> the company had underestimated
the amount of water going into the mine and
> that this year's
production would be "well below" its annual capacity. He
> also said
that increased pumping capacity was staying ahead of
>
greater-than-expected water flow, but a concrete barrier was taking
longer
> to build than expected. Grandey said the mine could be closed
for as long as
> six months, with Cameco losing up to $5 million in
profit for every month
> McArthur River is out of production.
>
> Although flooding can be a problem for any underground mine, it
is
> particularly worrisome at McArthur River, because of production
and
> processing taking place primarily underground.
>
>
The main shaft plunges 685m, and Cameco is currently mining
uranium-bearing
> rock between the 530m and 640m levels. Underground
processing was seen as a
> way to minimise the mine's environmental
impact. A grinding mill at the
> lowest level of the mine has already
been flooded. In its latest update,
> Cameco said the critical area of
the mine, 640m below the surface, contains
> processing equipment and
large pumps that would be lost if pumping capacity
> does not keep up
with the water coming in.
>
> A concrete barrier has been poured,
and is expected to take several weeks to
> cure. In the meantime, the
company will continue its efforts to ensure that
> it stays ahead of the
water, and protects the deeper, critical part of the
> mine.
>
> Mine personnel have improved the method of measuring water inflow
and
> determined that the flow rate is higher than previously estimated.
However,
> they have successfully added more pumping capacity. Water
treatment
> capacity, on the surface, has also been substantially
increased and is
> currently capable of matching the pumping
capacity.
>
> © Copyright Wilmington Group plc
>
>
> _______________________________________________
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mailing list
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>
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