DRC-2011-006169 - 0901a0688023894f

June 1, 2011
VIA E-MAIL AND OVERNIGHT DELIVERY
Mr: Rusty Lundberg
Utah Department of Environmental Quality
195 North 1950 West
P.O. Box 144850
Salt Lake City, UT 84114-4850
Denison Mines (USA) Corp.
1050 17th Street, Suite 950
Denver, CO 80265
USA
Tel: [phone]
Fax:[phone]
www.denisonmines.com
Re: May 10, 2011 Revised Confirmatory Action Letter Regarding Cell 1 Inspection and Repairs
Dear Mr. Lundberg:
This letter responds to the Utah Division of Radiation Controls ("DRC's") May 10, 2011 Revised Confirmatory
Action Letter regarding Denison Mines (USA) Corp's Plan and Schedule for Cell 1 Inspection and Repairs.
Denison's response to each of the confirmatory actions identified in DRC's May 10, 2011 letter is provided
below. The actions are repeated verbatim in italics, followed by Denison's response.
1 Submit Pictures of the Tailings Cell 3 standpipe extension and the Cells 1 and 3 standpipe covers.
Status of Cell 1 and Cell 3 LDS Standpipe Cap and Extension
DRC's conference call with Denison on April 28, 2011 has resulted in some misunderstanding regarding the
status of the Cell 1 and Cell 3 LDS standpipe covers and extension. During that discussion, Denison advised
DRC that:
a) A cover and standpipe extension had been installed on Cell 1. Photograph documentation has been
provided in Attachment 1 to this letter.
b) A cover had been installed on the Cell 3 standpipe. Photograph documentation has been provided in
Attachment 2 to this letter.
c) The status of the Cell 3 standpipe extension needed to be confirmed. DRC's statement in the May 10,
2011 Revised Confirmatory Action Letter is incorrect in stating that "DUSA claimed ... that they had
added an extension to the Cell 3 standpipe." Although Denison did not notice DRC's request to
respond in writing within three days of receipt ofthe May 10, 2011 letter, the correct status is described
below.
Plan and Schedule for Cell 3 LDS Standpipe Extension
Denison installed a cover on the Cell 3 standpipe, and evaluated adding an extension to the Cell 3 standpipe, in
December 2011. Subsequently, Mill personnel evaluated methods to add an extension to the standpipe. Mill
personnel determined that extension of the standpipe, in its current geometric configuration, would place the
extension in the middle of the roadway on the Cell 3 dike, causing a potential safety hazard and obstruction to
traffic. Denison has since developed a possible modification of the standpipe configuration that would allow
C:\Users\jtischler\Desktop\06.01.11_response_to_05.10.11_letter_Cell_1_lnspection_and_Repairs[1].doc
Letter to Mr. Rusty Lundberg
June 1, 2011
Page 2
extension of the standpipe and, at the same time, preserve vehicular access on the dike roadway. Denison
proposes to cut the standpipe back to a location lower down along the bank of the Cell 3 dike and install a "Y-
type" pipe split as follows. The straight run of LDS standpipe would be cut back, capped at a level lower than
the top ofthe dike, and the current bubble tube device removed from service. The second arm ofthe "Y" would
be a near vertical riser in which an upgraded leak detection monitoring device would be installed, as discussed
under item 2, below. Both arms of the "Y" would be away from (below) the trafficked area of the dike roadway.
Denison has not installed this modification, because we seek DRC's concurrence on the approach. As
discussed below, this proposed configuration modification will be installed at the same time as the monitoring
system upgrade described below, that is, within 45 days of Denison's receipt of DRC approval of this proposed
modification.
2. Provide a plan and schedule to replace the current leak detection method and equipment at the Cells 1
and 3 LDS standpipes.
Plan for Cell 1 and Cell 3 LDS Monitorinq Upgrade
Denison agrees to remove the existing blow tube monitoring devices from both the Cell 1 and Cell 3 LDS
standpipes. Each of the Cell 1 and Cell 3 standpipes would be fitted with level sensing probes coupled to:
a) A digital level readout
b) An alarm light
Each cell's LDS standpipe would also have a dedicated manual start pump. The level sensors would be set to
activate the alarm light when it detected any liquid level in the standpipe. Mill environmental personnel would
record the LDS liquid level during the weekly tailings inspection. They would also check the alarm light during
the daily tailings inspection and if the alarm light indicated a liquid level during any inspection, the
environmental personnel would turn on the pump, and proceed with the sample collection, fluid flow rate
determination, and notice procedures consistentwith Condition 11.3 of the Mill's Radioactive Materials License.
At this time, level and alarm equipment is still being evaluated, and the exact equipment type for the installation
has not been specified.
Schedule for LDS Monitorina Upgrade
Denison will have the installation completed within 45 days of our receipt of DRC's approval of this plan.
Please contact me if you have any questions or require any further information.
Yours very truly,
DENISON MINES (USA) CORP.
Jo Ann Tischler
Director, Compliance and Permitting
cc: David C. Frydenlund
Harold R. Roberts
David E. Turk
DENISON
MBNES
Letter to Mr. Rusty Lundberg
June 1, 2011
Page 3
K. Weinel
Central files
DENISON
MINES
Attachment 1
Photographs of Cover and Extension of Cell 1 LDS Standpipe
Attachment 2
Photographs of Cover of Cell 3 LDS Standpipe