DRC-2009-002804 - 0901a06880124b70

^l^^H b^6-e3CO^-^0^?0^
Denlson Mines (USA) Corp,
105017th Street, Suite 950
Denver, CO 80265
USA
Tel : [phone]
Fax:[phone]
www.denisonmines.com
DENISOhTi/
MINES
June 29, 2009
Mr. Loren Morton
State of Utah Depanment of Environmental Quality
Division of Radiation Control
168 North 1950 West
Salt Lake City, Utah 84114-4850
Dear Mr. Morion:
Re: White Mesa Uranium Mill; Groundwater Discharge Permit No. UGW37004-
New Decontamination Pad
Reference is made to items (c) and (d) of our letter of June 5, 2009 pertaining to the new
Decontamination Pad at the White Mesa Mill (the "New Decontamination Pad"). More
specifically, Denison agreed to provide an ALARA justification relating to the re-use/recycling
of wash water (as per the design of the New Decontamination Pad) and £in amendment of the
Discharge Minimization Technology ("DMT") Plan to include: 1) the manner of monitoring the
leak detection system for the New Decontamination Pad; and 2) the manner of inspecting it
(including the form or change in the existing form) to document such inspections. Accordingly,
the ALARA justification is as presented below and the modifications to the DMT Plan are
outlined below and included as attachments to this letter.
ALARA Definition (UAC R 313-12)
ALARA (acronym for "as low as is reasonably achievable") means making every reasonable effort
to maintain exposures to radiation as far below the dose limits as is practical consistent with the
purpose for which the licensed or registered activity is undertaken, taking into account the state
of technology, the economics of improvements in relation to state of technology, the economics
of improvements in relation to benefits to the public health and safety, and other societal and
socioeconomic considerations, and in relation to utilization of nuclear energy and licensed or
registered sources of radiation in the public interest.
Radiological Considerations
The radiological considerations of re-use/recycling of the wash water at the New
Decontamination Pad can be divided into two categories; worker exposure and public exposure.
Each of these is addressed below:
Worker Exposure Considerations
Worker Exposure at the New Decontamination Pad is minimal due to the nature of the
operation. The radioactive materials that could be present on the vehicles being washed
would be in the form of a residue in lieu of a suspendable dust which might otherwise
become available for inhalation. The operation is wet and dust suspension does not occur
during the process, thus eliminating the possibility of the inhalation pathway. External
exposure from gamma radiation due to these low specific activity residues is
immeasurable and would therefore not represent an exposure to the worker. Finally,
workers assigned to the New Decontamination Pad do nol wear their work clothing
offsite and are monitored per standaid operating procedures prior lo exiting the restricted
area, thus assuring contamination control to offsite locations and/or members of the
public. The net exposure difference to workers assigned to the New Decontamination
Pad does not result in exposure above lhat already experienced al the existing
decontamination pad, or above lhat for workers assigned to olher operations on the ore
pad.
Public Exposure Considerations
The use of the New Decontamination Pad represents no net exposure difference when
considering exposure to members of the public. The New Decontamination Pad is
located within the restricted area and any exposure related to its use is limited to its
immediate location (i.e. wet operation absent any dust re-suspension). Vehicles cleaned
at the Pad are surveyed for either unrestricted release or for restricted (exclusive use)
purposes, and in each case the vehicles must meet the requiremenis for release, thus
assuring lhat public exposure is limited to that allowed by regulation.
Regarding ALARA considerations, Denison has sucessfully utilized an existing
decontamination pad for several years, which employs the same re-use/recycling
provisions for wash water proposed for the new Decontamination Pad. Vehicles exiting
the existing decontamination pad facility are required to meet the alpha standard of 1000
dpm/100 cm^ (combined fixed and removable). This same standard will apply to the
New Decontamination Pad. In addilion, Denison applies ALARA lo site radiation
monitoring activities generally by setting an ALARA goal of 25% of the required limit.
However, with respect to vehicle surveys, all instances where readings are observed to be
above the instrument background result in re-cleaning of the contaminaied area until
instmment background is observed. Thus, for vehicle surveys the ALARA goal is
contamination free.
In order to assess the effectiveness of the wash water, and any contribution il may have lo
conlamination events, a review of vehicle release surveys over the past 30 days was
conducted. The review included the survey results for 453 vehicles exiting the property
afler having been decontaminated at the existing decontamination pad. For these 453
vehicles (generally including as many as 37 survey locations per vehicle) approximately
16,761 individual survey measurements were recorded. Ofthe tolal surveyed individual
locations, only 41 measurements (0.24 %) revealed readings in excess of background.
DENISON ^/
MINES
These were nearly always at locations where muddy residues were observed. In addition,
after re-wash (wilh the existing decontamination pad re-cycled water) the previously
surveyed locations were found to be less than background. Since approximately 99.76%
of the vehicles surveyed did not exceed instmment background upon initial survey (after
being washed with re-cycle water), and because re-washing the remaining 0.24% of
survey locations with re-cycled water reduced the vehicle to a contaminant-free state, it
can be concluded that the recycled water is not a contributor to vehicle conlamination.
Alternately, if the re-cycled water were a significant contributor to conlamination of
vehicle surfaces, then the vehicle surveys would have revealed a large number of above-
background observations, which was nol the case. Additionally, re-washing in those few
instances where elevated readings were observed would not have resulted in
contaminant-free surfaces if the recycled water was a significant source of contaminaiion.
Because the limitations applied lo conlamination on vehicle surfaces are protective of the
public and because the current re-cycling activities have not indicated that the wash waler
contributes to surface contamination, Denison believes that ALARA has been met. In
addilion lo this radiological consideration, waler resource conservation should be
considered. Even if it could be demonstrated that the use of fresh water (absent recycle)
would reduce the surface contamination of vehicles, there are a costs to this benefit. First,
there would be a use of waler resources amid this semi-arid region of San Juan County,
Utah. Second, the provision of fresh waler feed to the New Decontamination Pad would
result in the ultimate discharge of more water to the Mills tailings cells, thereby
occupying evaporative capacity in the tailings ponds that would otherwise be available to
reduce solutions in the ponds. Denison believes that these costs far outweigh any
potential reduction in surface contamination of vehicles below the already non-delectable
levels. Such a reduction would therefore not be ALARA.
In summary, Denison's existing decontamination pad recycled wash-water practices are
protective of workers and the public, and since vehicles are not being contaminated by
the re-cycled water, il does nol appear lo be "reasonable" to modify the syslem for fresh
water use as no net gain will be experienced. In addition, the re-cycling option provides a
conservation benefit in that a water resource (which would otherwise be available lo a
variety of uses in San Juan County) would nol be unjustifiably wasted and otherwise
occupy existing evaporative capacity without cause.
Given the above analysis, it can be concluded that exposures to the workers at the
Decontamination Pad and/or to members of the Public will nol resuil in any increase due lo this
operation, and that the use of re-cycled water at the Pad is ALARA. More specifically, the data
do not support the supposition lhat conlamination of vehicle surfaces would be reduced through
the use of fresh waler, and the current Company controls demonstrate that vehicles exiting the
restricted area are well within regulatory standards and the Company's ALARA goal. In
addition, any potential benefits from the freshwater feed scenario are outweighed by the costs of
achieving those benefits.
DENISO
MINES
rDi
Discharge Minimization Technology (DMT) Plan Modifications
Denison proposes to modify its DMT Plan lo incorporate the changes requested by the Division.
More specifically, Denison proposes to modify the DMT Plan al page 4 lo further describe the
proposed leak deteclion system and to describe the means by which leak detection will be
observed and inspected. Denison also proposes to modify the Daily Inspection Form al Section
VII, (page 22 of the DMT) to document the conduct of leak detection observations. These
proposed modifications are attached in redline/slrikeout formal lo accommodate the Division's
review of the proposed changes.
If you should have any questions regarding this ALARA analysis or the attached modifications
lo the DMT Plan, please contacl me.
Yours very tmly.
DENISON MINES (USA) CORP.
Steven D. Landau
Manager, Environmental Affairs
Cc Ron F. Hochstein
David C. Frydenlund
David E. Turk
DENISO
MINES
ffJMm
Attachments-Proposed Modifications to the DMT Plan
White Mesa Mill - Standard Operating Procedures 9/08 Revision: Denison-6
Book 11: Environmental Piotection Manual, Section 3.1 Page 4 of 37
Whenever the leak detection system pump is operating and the flow meter
totalizer is recording, a notation of the dale and the time will be recorded on the
Daily Inspection Data form. This data will be used in accordance with License
Condition 11.3.B through 11.3.E of the Mill's Radioactive Materials License, to
determine whether or not the flow rale inlo the leak delection syslem is in excess
of the License Conditions,
q) An estimate of the percentage of the tailings beach surface area and solution pool
area is made, including estimates of solutions, cover areas, and tailings sands for
Cells 3 and 4A.r)
r) In order to assure that the primary containment ofthe Decontamination Pad water
collection svstem has not been compromised, and to provide an inspection
capability to detect leakage from the primary containment, vertical inspection
portals will be installed between the primary and secondary containments. These
portals will be visually observed on a daily basis as a means of detecting anv
leakage from the primary containment into the void belween the primary and
secondary containment. The conduct of these inspections will be recorded on the
Daily Inspection Data Form (Section VII) and any observation of fluid between
the primary and secondary containments will be reported lo the Radiation Safety
Officer (RSO). The RSO will be responsible lo investigate the reason for the
presence of fluid between the primary and secondary containments and to direct
any necessary repair to the primary containment as a means of abating further
leakage.
Items (a), (m), (n), and (o) are to be done only when the Mill is operating. When the Mill is down,
these items cannot be performed.
'^ •/*
VD 00
c o c/1
C <u Q
c o
VI
> dj
Pi
00
o
a\
<+-o (N (N
1)
tJl
a CL,
QJ
n -n (\> 1
c
11) n, O
•n S3 "O
03
C/5
.^. s
flJ
S U
c rj
CJ
t/D
=1 c
rt S r-
O
CJ
f 1 u, cu
rt
C 1)
n
h >
W
—
.i<f! O
o
oa
u
u
z
o
H u u
H
1—< >
"0|
c o tJ
<i
u
IJ U
13
•o
o
U
cu
-is
<u
U
T3
CJ
u
cu
cu
T3
CU
U
Q
Q
Q
1
Q
tj
Q
Co
n
t
a
c
t R
S
O I
f
Li
q
u
i
d i
s O
b
s
e
r
v
e
d
In I
n
s
p
e
c
t
i
o
n P
o
r
t
a
l
In
i
t
i
a
l
le
v
e
l
In
i
t
i
a
l
le
v
e
l
In
i
t
i
a
l
le
v
e
l
In
i
t
i
a
l
le
v
e
l
11
1 1
iZ ii
1 1
<u
CU
Q. ^ 1 O Q.
T3
^ i
O D.
T3 cu
a. ^ 1 O a.
Le
a
k D
e
t
e
c
t
i
o
n
Sy
s
t
e
m C
h
e
c
k
e
d