Depleted Uranium
Technical Brief

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      Depleted Uranium
         Technical Brief
        EPA402-R-06-011

         December 2006
          Project Officer
          Brian Littleton
U.S. Environmental Protection Agency
  Office of Radiation and Indoor Air
    Radiation Protection Division

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Ill

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                                 FOREWARD
    The Depleted Uranium Technical Brief is designed to convey available information
and knowledge about depleted uranium to EPA Remedial Project Managers, On-Scene
Coordinators, contractors, and other Agency managers involved with the remediation of
sites contaminated with this material. It addresses relative questions regarding the
chemical and radiological health concerns involved with depleted uranium in the
environment.

    This technical brief was developed to address the common misconception that
depleted uranium represents only a radiological health hazard.  It provides accepted data
and references to additional sources for both the radiological and chemical
characteristics, health risk as well as references for both the monitoring and measurement
and applicable treatment techniques for depleted uranium.
                                       IV

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                                   Acknowledgments

       This technical bulletin is based, in part, on an engineering bulletin that was prepared by the U.S.
Environmental Protection Agency, Office of Radiation and Indoor Air (ORIA), with the assistance of
Trinity Engineering Associates, Inc. (TEA) under Contract No.68-D-00-210, and EnDyna, Inc. under
Contract No. 06-H-00-1057.

       Thanks go to Ron Wilhelm, Madeleine Nawar and Schatzi Fitz-James of ORIA, and Charles
Sands, Stuart Walker, Robin Anderson, and Kenneth Lovelace of OSWER for their comments and
suggestions and to the following EPA regional staff: R2: Angela Carpenter; R3: Randy Sturgeon; R4:
David Dorian; R6: Camille Hueni, Raji Josiam and George Brozowski, RIO: Rick Poeton.

This document has been changed from the original publication dated December 2006. This version
corrects references in Appendix 1  that improperly identified the content of Appendix 3 and Appendix 4.
The document also clarifies the content of Appendix 4.

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                               TABLE OF CONTENTS

1. PURPOSE	1
2. INTRODUCTION	1
  2.1  Characteristics of Uranium and Depleted Uranium	1
  2.2  Health Concerns	2
    2.2.1  Exposure Pathways	2
    2.2.2  Chemical Risk	3
    2.2.3  Radiological Risk	3
3. URANIUM IN THE ENVIRONMENT	4
  3.1  Occurrence	4
  3.2  Geochemistry	4
  3.3  Mobility	4
  3.4  Enhanced Mobility	4
4. FATE AND TRANSPORT OF DEPLETED URANIUM	5
  4.1  Fate in Soil	5
  4.2  Fate in Water	6
  4.3  Fate in Air	6
  4.4  Fate in Biota	7
  4.5  Partition Coefficients	7
  4.6  Fate and Transport Modeling	7
5. SITE SCREENING FOR DEPLETED URANIUM CONTAMINATION	8
6. MEASUREMENT TOOLS AND MONITORING TECHNIQUES	9
7. REMEDIATION  TECHNOLOGIES	9
  7.1  Soil Technologies	9
    7.1.1  Physical Separation	9
    7.1.2  Chemical Extraction	10
  7.2  Groundwater Technologies	10
    7.2.1  Pump and Treat	10
    7.2.2  Permeable Reactive Barriers	10
    7.2.3  Commercial Test Studies	10
  7.3 Technologies for Soil and Water.	11
    7.3.1  In-Situ Stabilization/Treatment	11
    7.3.2  Phytoremediation	11
    7.3.3  Monitored Natural Attenuation	11
8. EPA STANDARDS APPLICABLE TO DEPLETED URANIUM SITES	12
  8.1  For Soil	12
  8.2  For Air	12
  8.3  For Water	12
  8.4  Storage of Depleted Uranium	12
  8.5  For Disposal	13
Acronyms	14
Glossary	15
Additional Sources of Information	17
Appendix 1: Technical Background on Uranium and Depleted Uranium	19
Appendix 2: Measurement Tools and Monitoring Techniques	23
Appendix 3: National Priorities List (NPL) Sites that have or may have DU Contamination	28
Appendix 4: Depleted Uranium Manufacturing and Testing Facilities	30
Appendix 5: Case Study - Nuclear Metals, Inc. (NMI) site, Concord, Massachusetts	32
Appendix 6: Case Study - Maxey Flats Nuclear Disposal Site, Hillsboro, Kentucky	35
Appendix 7: Treatment Defined by NCP	37
References	38
                                         VI

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1. PURPOSE

Technical Briefs are d     esigned to convey
available information and knowledge   about a
particular c ontaminant   of interest, such as
depleted uranium  (D U), to the Environm   ental
Protection Agency  (EPA) Remedial Project
Managers (RPM), On-Scene Coordinators
(OSC), contractors, and other site cleanup
managers involved with the remediation of sites
contaminated with radioactive material.

This Technical Brief i s intended to help the user
understand t he characteristics, behavior in the
environment,  and potential human health risks of
DU as a contaminant in soils and grou ndwater.
The document also        identifies a  vailable
monitoring and measurement tools and various
treatment technolo gies for rem ediation of sites
contaminated with DU. Supplem        entary
discussions   and additional information are
provided in the appendices.

This Technic al Brief spe cifically addresses D U
in an environmental contam ination setting and
specifically does not consider airborne DU
micro-particulates of the type associat  ed with
DU  munitions. Further,   it considers onl    y
contamination scenarios   in the United States,
though it has used international scientific data,
where appropriate, for its technical basis. In
these environmental contamination sett ings, the
major risk from DU is toxicological rather than
radiological, and chem ical toxicity  is the major
driver for site cleanup.

Further, since     most available literature
concerning chemical properties of uranium focus
on natural uranium  , this docum  ent will  make
frequent reference to t    hese studies  in full
knowledge that the chem       ical properties
addressed fo r natural uranium  ar e ide ntical to
those of DU. Adden      da will be issued
periodically  to update th  e original Technical
Brief, whenever deemed necessary.

2. INTRODUCTION

Depleted uranium (DU) is a by   product of the
process used to enrich natural uranium for use in
nuclear reactors and in nuclear weapons. Natural
uranium is c omposed of three isotopes;    234U,
235U, and 238U (see Table 1) [1]. The enrichment
process concentrates both the  235Uandthe 234U
isotopes in the product  material, resulting i n a
waste product or byproduct depleted in both 235U
and 234U.   The resultant  DU retains a smaller
percentage of   235U and   234U, and a slightl  y
greater percentage of   238U (99.8%   by mass
instead of 99.3%). Because of the shorter half-
life of 234Uand  235U compared to   238U,the
radioactivity associate   d with        DU i   s
approximately  40% less than that o    f natural
uranium.

Table 1: Typical  Isotopic Abundances in Natural
        and Depleted Uranium
 Isotope
Abundance (by weight)

234U
235U
238U
Natural Uranium
0.0058%
0.72%
99.28%
Depleted Uranium
0.001%
0.2%
99.8%
In the Unite d States, DU is available mainly
from the U.S. Department of Energy (DOE) and
other govern ment sources.  DU occurs in a
number of different co  mpounds with  different
characteristics, which   may  have a si  gnificant
impact on the  management and dispo sition of
this material.

Because DU metal is 1.7 times more dense than
lead, it is va luable for industrial uses. It    has
been used f or civil and  military purposes for
many years. Detailed information on uranium  ,
its che mical form s,  manufacturing/enrichment
processes, and uses of DU are further d iscussed
in Appendix 1.

2.1  Characteristics of Uranium and
     Depleted Uranium
Uranium is  a naturally  occurring radioactive
metal in all rocks and soils in low concentrations
(1 to several hundred     picocuries per gram
(pCi/g)). All three isotopes are radioa ctive and
produce decay  product  s upon radioactive
disintegration. After purification (processing) of
uranium, the decay   products of all    of the
uranium i sotopes will beg in to accu mulate very
slowly, and traces of thes  e decay products can
be detected.

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Other trace i sotopes that have been observed in
depleted uranium   , an  d are likely        of
anthropogenic origin, in  elude pluton ium-238
(238Pu), plu tonium-239 ( 239Pu), plu tonium-240
(240Pu), americium-241 (241Am), neptunium-237
(237Np) and technetium-99 (99Tc).

Table 2: Radiological Properties of Uranium
        Isotopes
Isotope
Half-life (years)
234U
235U
238U
2.455
7.038
4.468
105
108
109
Table 2 above lists the hal f-life of each isotope.
Approximately 48.9% of the radioactivit y of
natural uranium is associated with 234U, 2.2% is
associated w ith 235U, and 48.9% is a   ssociated
with 238U. All three isotopes behave the same
chemically  but have different radiolog    ical
properties. As may be calculated from the tables,
the radioactivit  y of    natural uranium  is
approximately 0.7  0   uCi/g, whereas the
radioactivity of DU is approximately 0.40 uG/g.

The weight percentages in Table 1 and
radioactivity percentages given previ   ously are
different bee ause  each i sotope has a   different
physical half-life - the shorter half-life    makes
234U the most radioactive and the longer half-life
makes 238U the least radioactive. Each isotope
decays by emitting an alpha particle.

For natural uranium  present in soils and rocks,
the activities of 234U and 238U are identical; they
are said to be in secular eq  uilibrium.  In natural
waters, how ever, the  234U can appear to be
slightly more soluble and the radioactivity ratio
of  234U to  238U varies from  1:1 to m  ore than
20:1. This is believed to be due to the fact that as
238U decay s to 234U, it passes through t  horium-
234 ( 234Th) ( first decay product) and then
protoactinium-234 (   234Pa) (  second   decay
product) which are slightly  m ore soluble than
the uranium isotopes. The  234U thus appears to
move while the  238U remains sparingly soluble.
When converting from activity to m ass or vice
versa, knowledge of the  concentration of each
the three uranium isotopes is required.
2.2  Health Concerns

A common misconception is that radiation is the
primary hazard DU poses to hum an health.  This
is not the case under   most exposure scenarios.
Though irradiation from DU can occur, chemical
toxicity is usually the major hazard from soluble
forms of uranium, while the radiological hazard
dominates inhalation of sparingly soluble forms.
Since all for ms of urani um posses s the sa me
inherent chemical properties, they also displa   y
the same behaviors of chemical toxicit y, and if
internalized, will all   le  ad to adverse health
effects si milar to those of other   heavy m etals
such as 1 ead and cad  mium. The Age ncy for
Toxic Substances and Diseas       es Registry
(ATSDR) To xicological Profile on uranium  [1]
summarizes the existing a nimal and human data
on the toxicology of natural uranium.

Natural and depleted uranium differ only in their
relative concentrations of uranium    isotopes.
Depleted uranium is roughly 60% as radioactive
as natural uranium because the more radioactive
isotopes have been removed.  All three naturally
occurring uranium isotopes emit alpha  particles
as their primary    radiation.    Because alpha
particles cannot penetrate the skin, ur  anium is
usually considered an internal radiological
hazard rather than an exte rnal radiation hazard.
Awareness should be m aintained regarding the
external hazard since DU can contain trace
amounts of 236U and other substances (such as
plutonium, am   ericium,    and technetium);
however, the risk posed by        these trace
contaminants is usually       regarded as
insignificant.

2.2.1  Exposure Pathways
Uranium occurs widely in the environment, and
asaconseq uence small am   ounts of natural
uranium in air, water, and   soil are ingested and
inhaled every day. This normal intake results in
a natural level of uranium in the       body of
approximately 90 ug [1]. Excess loading  occurs
through thre e exposure p athways - i nhalation,
ingestion, and dermal contact - thoug h the latter
(dermal) i  s usually   considered to be an
insignificant exposure scenario.

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Inhalation is the m ost likely route of  i ntake of
DU. In the case of sites c ontaminated with DU,
this  may occur through  resuspensio n in the
atmosphere t hrough wind or dust disturbances
due to site operations. Accidental inhalation may
alsooccurasa  consequence of fire  in a  DU
storage facility, an aircraft crash, manufacture of
armor-piercing weapons, or the decontamination
of contaminated objects. [34]

Ingestion can occur in a large s     ection of a
community o r populatio n if drinkin g water or
food supplies become contaminated with DU. In
addition, in  gestion of   soil b y chi Idren is
considered a potentiall  y significant pathway
[34].

Dermal con  tact is   considered a r   elatively
unimportant type of expos ure since little of the
DU will pass across the skin int    o t he blood.
However, D U could ente r sy stemic ci rculation
through ope n wounds    or from    embedded
fragments of DU [34].

2.2.2 Chemical Risk
When incorporated into the body  , the highest
concentrations of uranium occur in the  kidne ys,
the m ost sen sitive organ, as well as liver tissue
and skeletal  structure.    The am  ount of DU
subsequently absorbed into the b      lood and
deposited in the kidne  ys or other organs is
dependent u pon several factors (e.g., exposure
pathway,  particle size,    solubility) [  1]. DU
particles and oxides retained in the   body have
different solubilities. The three uranium oxides
of prim ary c oncern (UO 2, UO 3, and U 3O8) are
relatively insoluble [35]. Insoluble and sparingly
soluble uranium compounds are believed to have
little potential to cause renal toxicit  y but could
cause pulm  onary toxicit y throu gh i nhalation
exposure [1].

The ingestion exposure pathway currently has a
number of established risk levels and standards
for chem ical toxicit y. ATSDR has a  "minimal
risk" level for intermediate-duration ingestion
set at an oral uptake of  2 (ig of uranium per kg
of bod  y weight per day   , though the   World
Health Organization (W HO) has established a
tolerable daily intake (TDI) for uranium  of 0.6
(ig/kg bod y weight per day   . WH O has   a
provisional guideline for drinking water quality
of 15 (i g/L - a value considered to be protective
for sub-clinical renal effects repo       rted in
epidemiological studies.     EPA's Rule     on
Radionuclides in Drink    ing Water  sets   a
maximum contam  inant   level for naturally
occurring uranium   at    30 (i g/L, and its
preliminary remediation goal (PRG)  for
Superfund is 2.2 2 (i g/L for 238U in tap water.
The Nucle   ar Regulat   ory Commission'   s
occupational annual lim it on i ntake ( ALI) for
oral ingestion is 14.8 mg.

2.2.3  Radiological Risk
The general populati on is exposed to  uranium
primarily th rough fo od and water with an
average annual intake from  all dietary  sources
being abo ut350  pCi   [31]. On   average,
approximately 90  |o,g (m icrograms)  of uranium
exists in the human body from natural intake of
water, food, and air.  About 66%  is found in the
skeleton, 16% in the liver, 8% in the  kidne    ys,
and 10% i n other tissue  s [ 32]. Inth e United
States, the typical concentration of uranium   in
the skeletal structure (wet weight) is  about    0.2
pCi/kg [31].  The lungs   , kidne ys, a nd bo ne
receive the  highest annual doses of radiation
from uranium, estimated at 1.1, 0. 92, and 0.6 4
mrem, respectively, for U.S. residents.

As they decay, DU and its decay  products e mit
alpha, beta, and gamma radiation that can result
in external and internal exposure to those who
handle or encounter DU-contaminated materials.
Based on the zero-threshold linear dose  response
model, any  absorbed dose of uranium      is
assumed to result in an in creased risk of cancer.
Since uranium tends to  c oncentrate in specifi c
locations in the body , the risk of  cancer of th e
bone, liver, and bloo d (such as leukemia)  may
be increased.

Inhaled DU particles that reside in the lungs for
long periods of time may damage lung cells and
increase the possibility   of lung cancer after
many  years.  D  U is co nsidered primarily  an
internal hazard, although there is some external
radiation hazard associ ated with DU   since it s
progeny emit gamma rays.

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The amount of uranium in the air is usually very
small and effectively insignificant for re medial
operations. People who live near federal
government facilities that produced or tested
nuclear weapons in the p   ast, or facilities that
mine or proc ess uranium ore or enrich uranium
for reactor fuel, may have increased exposure to
uranium. For exam  pie, d ata fro m the United
States and Canada have shown elevated uranium
levels in and around m    illing and   processing
facilities,  and esti mated airborne releases of
uranium  at one DOE facility   am  ounted to
310,000kg  between 195 1  and  1988, which
produced an  estim ated offsite inven  tory of
2,130-6,140 kg of excess  uranium in  the top 5
cm of soil in the vicinity of the facility [34].

3. URANIUM IN THE ENVIRONMENT

Due to its natural  abund   ance, uranium can be
found an ywhere in water, in food,     and air.
Because DU and naturally   occurring  uranium
are chem ically the same, knowledg    e about
transformation, transport,  fate and effect on
natural uranium in the environment is applicable
to the study of DU.

3.1  Occurrence
As  an environm  ental conta minant,  DU m ost
frequently occurs as the metal, and as a num ber
of solid oxides, which may include those arising
from oxidation of the      metal, those fro   m
hydrolysis of uranium hexafluoride accidentally
released to the environm   ent, and those fro  m
neutralization of acidic industrial wastes that
contain dissolved DU.   11 can  also o ccur a s
soluble aqueous species   (primarily the urany  I
ion) or as a  number of in soluble and sparingl y
soluble species, including   mineral for ms that
have aris en as are suit of uranium 's  complex
environmental chemistry.

3.2  Geochemistry
Oxidation-reduction processes play a  major role
in the occurrence and behavior of uranium in the
aqueous envi ronment. The dom inant uranium
valence st ates that ar  e st able in the    geologic
environment are the uran ous (U 4+), and uran yl
(U6+, UO22+ ion) states; the former is m  uch less
soluble [ 2]  while the latter can form     many
complexes and is regarded as a dominant feature
of uranium chem  istry. For the     metal, the
oxidation rat e is likel  y to be contr  oiled by
variables sue h as te mperature, metal size and
shape, prese nee or absence of coatings, soil
matrix, and presenc   e  of water  a nd other
contaminants.

3.3  Mobility
Uranium transport generally occurs in oxidizing
surface water and groundwater as the urany I ion,
UO22+, or as urany    I fl uoride or c  arbonate
complexes. UO    22+ and uran    yl fluori  de
complexes dom inate in acidic oxidizing acidic
waters, whereas the carbonate com       plexes
dominate in near-neutral and  alkaline oxidizing
waters, respectively . In contrast, the uranous
ion, U4+, is essentially  ins oluble. An im portant
point in cons idering urani um migration in soils
is that when UO 22+ is reduced to U 4+ by humus,
peat, or  other organic     matter or anaerobic
conditions, it is essentially imm     obilized. It
should also  be noted   that phosp hates and
sulfides usually precipitat e uranium and hence
stop migration, a behavior that can be  exploited
in remedial operations.

Hydroxyl,   silicate, organic, and sulfate
complexes might also   be i mportant, sulfat e
especially in mining and milling operations that
use sulfuric acid as a leaching agent. Maxi mum
sorption of uranyl ions on natural materials (e.g.,
organic  matter; iron, m   anganese and titaniu m
oxyhydroxides, zeolites, and clay s) occurs at a
pHofS  .0-8.5.  The sorption of uranyl ions by
such natural media appears  to be rever sible. For
uranium to be "fixed" and therefore ace umulate,
it requires reduction to U4+ by the substrate or by
a mobile phase, such as hydrogen sulfide (H2S).

3.4  Enhanced Mobility
A further complication in predicting the mobility
of DU is the  existence of facilitated transport.
Facilitated transport is the accelerated movement
of contaminants in an aqu eous system at a rate
greater than would be pr edicted by e ither the
simple solubility of the contaminant, the form al
flow-rate of the aqueous phase,    or by   the
interaction of a contam   inant with the solid
phases present.  Facilitated transport is usually
attributed to the contam inant being b ound to
particles such as colloids  , or havi ng enhanced

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solubility  due to the presence of co  mplexants,
ligands, and/ or chelators. While the aqueous
phase in gen eral may be  able to explore a very
tortuous path through the geologic m edia when
contaminant attached to a particle that is too
large to travel through the smaller pathways, it is
effectively restricted to    wider cr   acks and
crevices, thus giving it an enhanced m    obility.
Colloids are ty  pically ti ny (spanning the size
range from 1 arge molecules to s mall biological
entities such  as bact  eria) particles of  mineral
and/or organic matter that can remain suspended
in the aqueous phase without settling. They may
be hydrol  y sis products   of uranium , organic
chelates (natural and anthropogenic lig ands), or
mineral/oxide/humic colloids.

4.  FATE AND TRANSPORT OF
DEPLETED URANIUM

Environmental contam ination b y DU can occur
in soil, water, biota, and as airborne particles.
Although the radiological properties  of uranium
isotopes differ considera  bly, their c   hemical
behavior is essentially identical. Hence,
knowledge about the transform ation, transport,
fate, and effect of natural uranium in the
environment is applicable to DU.

Under some conditions,  such as the   reducing
conditions characteristic of swamps and
wetlands, the stable chemical form of uranium is
the +4 state i n which it will not readil y dissolve
in water, and will thus beco       me relatively
immobile. Under oxidizing conditions, such as
on the surface of the ground or in shallow water,
DU oxidizes  to a st ate in which it c an  dissolve
and become m obile in water. Metall  ic form s
will oxidize faster   as small particl  es than as
large pieces [37].

Aside fro m pH, a num  ber of ot her pa rameters
affect uranium fate and transport       .  Other
parameters that influence    movement are the
presence (or  absence) of organic com  pounds,
redox status, ligand concentrations (i.e.,
carbonate, fluoride, sulf  ate, phosph ate, and
dissolved carbon), alum   inum- and iron-oxi de
mineral concentrations, and           uranium
concentrations.
Given the long half-life of uranium (see Table
2), decay is not particularly relevant to uranium
fate and transport in th    e environm ent. The
following sections discuss DU fate/transport by
medium.

4.1  Fate in Soil
Upon weathering, n on-oxidized sm all  particles
maybeadso rbedto clay  minerals and hum us.
The surfaces of remaining DU fragments in soil
exposed to the atmosphere will slowly oxidize to
uranium oxides.
Uranium can  exist in the  +3, +4, +5, and +6
oxidation states. The +4 and +6 stat es are the
most common in the environm ent. These oxides
are onl y sparingl y sol uble, but will  gradually
form hy  drated uranium oxides in        moist
conditions.  The hy drated uranium oxi des will
then slowly dissolve and be transported  into the
surrounding  soil, pore water, and ev    entually
groundwater, although adsorption of uranium to
organic co mpounds in th e soil may inhibit the
rate of migration. It should be noted that the +6
form (uranyl ion) can be adsorbed on clay s and
organic compoun ds and  later be "eluted" or
displaced by other cations. However, many
organic mate rials reduce t he urany I ions to the
+4 form s w hich are not likely   to  be eluted,
though t hey might be su bsequently r eoxidized
and made soluble.)

In the case  of metallic p articles, the oxidation
rate depends on fragment size, pH,    humidity,
soil m  oisture content, soil chem     istry, soil
oxygen content, and the presence  of other metals
in the soil. The sy   stem's pH and dissolved
carbonate concentrations are the two m       ost
important factors influen  cing the ad  sorption
behavior of U6+ in soil [38].

Iron and  manganese oxides, smectite cl  ays, and
naturally occurring organi c matter can act as
somewhat irreversible sinks for uranium pres ent
in soils. As a result, so     rption  ont o iron and
manganese oxides can be an effective extraction
process, alth ough the pr  esence of d  issolved
carbonate can inhibit thi   s process.   Uranium
transfer between these bound   phases and the
dissolved phase is subject to very slow reaction
rates [38].

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Aqueous pH influences the sorption   of U6+ to
solids. The  poorer-adsorbing  uranium species
are most likely to exist at pH values between 6.5
and 10. Additionally , lowering the pH reduces
the num  ber of available exchange sites on
variably charged surfaces,  such as iron oxides
and natural organic matter.

Microbial activity might speed up the  corrosion
of metallic DU, but it should be noted that the
titanium present in DU of m      ilitary origi  n
(typically 3.5%) would tend to cou   nteract and
slow down the process [39]. On the other hand,
in soil with high concentrations of      organic
materials, naturally occurring soil   bacteria can
reduce soluble U  6+ to sparingl y sol uble U 4+,
thereby lim  iting  uranium mobility as well.
Oxygen content, presence of water, si  ze of the
metal particles, presence of protective coatings,
and the salinity of the water present al 1 impact
the rate of  microbial action.  Althou  gh it is
known that o rganic matter is a  sink for uranium
in soils and sedi ments, the actual  mechanism of
the process is still unclear [38].

4.2  Fate in Water
U4+ solid phases have relatively low solubilities,
so the total concentration of U   4+ in water is
usually low (3-30 m  g/L) [ 38]. In general,
aqueous U4+ forms precipitates that are sparingly
soluble, adso rbs strongl y to m ineral surfaces,
and partitions into organic  matter.  All  of these
properties lead to its reduced mobility in water.

Under reducing condi tions, U4+ is the dom inant
oxidation state in aqueous  solutions.  Reducing
conditions are found in    deep aquifers,   marsh
areas,  and e ngineered barriers. U   4+ is not
strongly co  mplexed by co  mmon   inorganic
ligands and is present    predominantly as the
U(OH)4 ion under pH conditions typical of most
natural waters. U    4+ precipitates t  o form
relatively insoluble solids, such as      uraninite
(UO2) and coffmite (USiO4) [40].

As previously m entioned, the U 6+  ions can b  e
removed from   solution  by sorpti  on on ir  on
hydroxides and organic    soil matter.  Sorbed
uranyl ions can be reduced to U 4+ by reductants
such as hydrogen sulfide (H2S), methane (CH4),
or ferrous iron (Fe 2+). If urany 1 ions are sorbed
by or ganic matter, the organic m   after  may
reduce the urany 1 i ons [ 40].  Urany 1 ions may
also be rem oved from solution by precipitation
as U 6+ solid phases such as schoepite (       3-
UO3«2H2O), which is relativel y solubl e, or by
precipitation of the less so luble phases carnotite
(K2(UO2)2(VO4)2) or              tyuyamunite
(Ca(U02)2(V04)2) [40].

Uranyl ions form stro      ng com  plexes with
carbonate ion in  solution.  T    hese carbonate
complexes  i ncrease the  solubility of uranium
solids, facilitate U  4+ oxi dation, and  increase
uranium  mobility by lim iting uranium sorption
in oxid ized waters  [40].  Fluoride, p hosphate,
and sulfate   ligands can also sig      nificantly
complex uranyl ions [40].
                                         6+ •
                                           IS
At low ionic strengths with low concentrations
of U 6+, the concentration of dissolve   d U
mostly cont rolled bye  ation exchange and
adsorption processes. As the ionic strength of a
solution increase  s, other cations (e.    g., Ca 2+,
Mg2+, K +) displace   any uranyl ions  on  soil
exchange sites and force them      b  ack into
solution.

4.3 Fate in Air
Atmospheric release  s of    DU are aim    ost
exclusively in particulate form, as the vapor and
gas forms of DU are not commonly encountered.
The high  density of DU in m   ost particulate
forms limits the air transport of DU to relatively
small particles. Airrel  eases of DU  can occur
via em ission from  stacks, re-suspension from
soil, or through em issions of fugitive dust fro m
piles or industrial process areas containing DU.

Source estimates for stack releases are generally
derived from stack monitors. The revis ed  wind
erosion equation [ 41] may be used to   estimate
releases via suspension from soil.  So  urces of
fugitive dust  releases to ai r are often esti mated
using the E  PA AP-42 guidance [   42].  Air
transport of long-term  ( Bone y ear) release s o f
DU in the form  of aerosols or other respirable
particle si zes is ty pically analy zed using codes
based on the G  aussian plume  model. Thes e
models estimate air concentrations as a function
of direction and distance from the so    urce, and
also will usually provide   esti mates o f ground

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concentrations resulting from deposition of the
airborne DU. It is reported that m ost of the DU
dust will be  deposited within a distance of 100
meters from the source [43].
Following airborne transp  ort, the m igration of
DU will ultimately  become subject to water,
soil, and bi  ological transport mechanism  s. In
general, DU deposited by airborne transport will
be present on or near the s  oil surface and shows
minimal uptake b y p lant roots.   D U is not
effectively tr ansported thr ough the fo od chain,
as low-level  organism s  tend to exc   rete the
soluble uranium species quickly.

4.4  Fate in Biota
Some plant materi al, such as lichens, can serve
as an indicator of airborn  e DU contamination.
Lichens consist of fungi and algae living
together sy mbiotically, in a  mutually beneficial
way.  As lich en morphology does not vary with
the seasons,  their accumulation of pollutants can
occur throughout the year, and the y usually live
for very long periods.
Some lichens growing on the surface of another
plant have    a high capacity   to accu   mulate
uranium. Because they lack roots, lichens do not
have access to soil         nutrient po   ols and
accumulate substances mainly     via  trapping
atmospheric particulates. Ura        nium is
accumulated in lichen thallus under moist and
dry conditions from airborne particles and d ust.
Even tin y fr agments of  lichens may contain
concentrations that are readily detectable [43].

4.5  Partition  Coefficients
Partition coefficient (K d) is a parameter used
when esti  mating t  he m igration potential of
contaminants present in aqueous solutions in
contact with surface, subsurface, and s uspended
solids. K   d is defined  as the ratio of the
contaminant concentration associ  ated  with the
solid to the  contain inant concentration in the
surrounding aqueous solution when the sy stem
is at equilibr ium. Gene ric or default   partition
coefficient values found i n literature can result
in significant errors   when used to pre  diet the
absolute im pacts of conta  minant migration or
site-specific remediation options.     Partition
coefficient values m   easured  at site-specific
conditions are    essential for sit    e-specific
calculations  [44].
With respect to uranium     movement in the
environment, however, the EPA guidance on K d
suggests that the best      way to m   odel the
concentration of precipitated uranium is through
the solubility constants of the different uranium
compounds i nvolved, rat her than thr ough K d
[44].

As with other uranium  properties, uranium  K d
values are strongly influenced by pH because of
the pH-dependent surface charge properties of
soil m  inerals and the     com  plex aqueous
speciation behavior of dissolved U6+.  In general,
at pH less than 3, the adsorption of ur  anium by
soils and single-m  ineral phases in carbonate-
containing aqueous solutions is low, reaching a
maximum in adsorption  between pH 5-8, then
decreasing at pH values   greater than 8   [44].
Table 3  provides  minimum and  maximum K d
values for u  ranium as a functio   n of  pH and
shows the wide variation that occurs in Kd.

4.6  Fate and Transport Modeling
Obviously, the best method for determ ining the
concentration of a contaminant at a location in a
contaminated site i  s by direct, sit   e specific
measurement  using  the appropriate analy  tical
method  and protocol.     The contain     inant
concentration is then us ually used t o determine
Kd for further    modeling purposes.   The use,
advantages, and lim itations of the K  d approach
have been well discussed in the literature [43 ],
and we recommend  that whenever possible Kd
should be measured. It is im portant to n ote that
soil scientists and geochemists knowledgeable of
sorption processes in natural environm ents have
long known that generic or default partition
coefficient v alues found in the literature can
result in significant errors when used t o predict
the absolute   impacts of c ontaminant migration
or site-remediation options. Accordingly, one of
the major reco  mmendations is that    for site-
specific calculations, partition coefficient values
measured at  site-speci    fie conditions are
absolutely essential [43 ].  However, due to the
complexities of both     geological media and
chemical behavior withi   n this media, the
necessary   measurements of conta     minant
concentration may not be possible. For example,
at a given point in a      geological  matrix, a
contaminant will be partitioned bet   ween th e

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groundwater and the host geological matrix, and
a "true"  measurement at that point    requires
removal of a sam  pie containing b oth the solid
and aqueous phase; this may not always be  easy
to achieve.  Ifsuchproble ms are the c ase, or if
the contam inant has not y  et reached exposure
points, environmental  fate and transport models
must be     used to predict conta      minant
concentrations.

Table 3: Kd Values for Uranium as a Function of
       PH
PH
o
J
4
5
6
7
8
9
10
Kd (mL/g)
Minimum
<1
0.4
25
100
63
0.4
<1
<1
Maximum
32
5,000
160,000
1,000,000
630,000
250,000
7,900
5
Source: [44- Table 5.15]. (See also reference 43, Table 5.18
and pages 5.79-5.81)

While m any  fate and  transport m  odels  are
available for various     media, this t   ype of
modeling is an area of active research with much
debate on the problem s associated with  existing
models and  little consensus on how chem   ical
reactions an  d reaction parameters sh   ould be
determined for field a pplications. The Federal
Interagency  Steering Committee on Multimedia
Environmental Models (ISCMEM) exists to
coordinate efforts am ong agencies that actively
use or supp  ort the deve  lopment of coupled
hydrologic and geochem ical models to si mulate
the transport of chem  ical contam inants in the
subsurface environment.

Fate  and transport     modeling is of great
importance i n radiation  risk asse  ssments and
conceptual site models required for remediation,
and considerable i mportance is attach ed to the
availability of expertise in their use.

5. SITE SCREENING FOR DEPLETED
URANIUM CONTAMINATION

EPA has published several guidance do cuments
on the approach for re     mediation of sites
contaminated with hazardous         materials,
including radionucli  des. Because of the
complexity  and com prehensiveness  of the
subject matter, the reader is advised to consult
the relevant details        in the f     ollowing
documents/websites:
  1.   "Distribution of OSWER Radionuclide
  Preliminary Remediation Goals (PRGs) for
  Superfund Electronic Calculator", February 7,
  2002.
  httD://eDa.aov/suDerfund/resources/radiation/i
  df/rad.pdf

  2.  Soil Screening Guidance, User's Guide,
  2nd Edition 9355.4-23, 1996. This Guide [3]
  provides a methodology to calculate risk-
  based, site-specific soil screening levels
  (SSL).

  3.  Soil Screening Guidance for Radionuclides:
  Technical Background Document, EPA/540-R-
  95/128, 1996 [4], and Soil Screening
  Guidance for Radionuclides: User's Guide,
  EPA/540-R-00-007, 2000 [5].

  4.  EPA website,
  http://www.epa.gov/radiation/radionuclides/ura
  nium.htm

  5.   Inventory of Radiological Methodologies
  for Sites Contaminated with Radioactive
  Materials, EPA/402-R-06-007, 2006 (See
  Table 10, page 42, for analytical
  methodologies applicable to each
  radionuclide, and Section 3.2.1  for discussion
  of water sample preservation and transport
  issues).
It should be noted that information on the
chemical toxicity of urani um is av ailable in the
ATSDR Toxicological Profile for Uranium   [ 1 ].
It should also be noted that since       uranium,
including DU, is both a chemical and
radiological hazard, SSLs for DU should
consider both types of    hazards. SSLs for
uranium should be calculated using both the  Soil
Screening Guidance for non-carcinogenic
chemicals and the Soil Screening Guidance for
Radionuclides.  Since the SSL is a numerical
concentration, it should be based on t   he most
protective health quantity, whether that is kidney
toxicity or radiological risk.

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6.  MEASUREMENT TOOLS AND
MONITORING TECHNIQUES

Uranium and DU can be detected by measuring
the different types of radi  ation (i.e., al pha, beta
and/or gamma radiation) em  itted. Presently , a
vast choice  of equipm ent for  monitoring such
radiation is available. Refer to Table 6,
Appendix  2,  for a description of      selected
specific  measurement tools and monitoring
techniques.

Measurements made with  field equipment are
typically less sensitive than laboratory
measurements and m   ay be im   paired b  y
environmental characteristics such as natural soil
composition. If these fi  eld measurements ar e
not, or are only partly , successful, field sa mples
must be collected and analyzed in a laboratory in
order to  obtain a com prehensive asse ssment of
the contamination.

EPA's Office of Radiation and     Ind oor Air
completed a draft compendium on the Inventory
of Radiological Methodologies, focusing on the
radionuclides likely to be found in soil and water
at contaminated sites. While it is not a com plete
catalog of analy   tical  methodologies, it is
intended to assist pr       oject   managers to
understand the concepts, requirements, practices,
and limitations of laboratory analyses unique to
radioactive environm ental  samples. Detailed
guidance o  n reco  mmended radioa  nalytical
practices may be found in current editions of the
Multi-Agency Radiol    ogical Laborator    y
Analytical P rotocols Manual (MARLAP) [  6]
and the Multi-Agency Radiation Survey and Site
Investigation Manual (MARSSIM) [7].

7.  REMEDIATION TECHNOLOGIES

Technologies for the      remediation of DU
contamination may involve one or more of the
following process es: ex   cavation and earth
moving, ph   ysical separation, chem      ical
separation, in-situ stabilization, or a combination
of these tech nologies. Re mediation of surface
and grou ndwater contain inated with DU   may
include conv entional pum p and treat methods
and/or permeable    reactive barriers   . These
technologies are described  in t    he f olio wing
subsections [8]. However, no technologies exist
that are c  apable of significantly  reducing the
chemical an dradiolog icaltoxicit y  ofDU,
characteristics also fundam   ental to  natural
uranium. Case studies of the rem ediation efforts
of two sites with DU contain   ination, Nuclea r
Metals, Inc.  in  Concord, Massa  chusetts, and
Maxey Flat  s in Hillsb   oro, Kentucky  , are
provided in  Appendix 5  and 6.  It  should be
noted that the following descri       ptions of
remediation technologies are brief and serve
only as a guide for furt    her investigation and
analysis. The evaluation and sel    ection of a
remediation technolog y can be a co     mplex
matter; critical issues incl  ude the phy sical and
chemical fo  rms of the    depleted    uranium
contaminant, phy sical an d che mical properties
of the contaminated media, and the presence of
other contaminants.  The technolog   ies below
broadly cove r DU contaminated sites, storage
sites, sites associated with UF6, and address DU-
contaminated soil and groundwater. In such
remedial situ ations, consideration  must also be
given to related  media, such as dust with the
potential to beco  me  airborne as a   result of
remediation operations. The scope    presented
here does not include    air pollution  such as
particulates from munitions and projectiles, and
in this regard it is worthy   to note that EPA is
unaware of any   National Priorit  y  List sites
associated with DU conta mination arising from
projectiles.

7.1  Soil Technologies
Several tech nologies hav e been developed for
use on DU-c  ontaminated soils [8].  E xamples
include:

•   Excavation, followed by disposal of soi Is in
    a low-level waste repository; and

•   Excavation of contaminated soil followed by
    treatment (i.e., phy   sical separation and
    chemical extraction).

7.1.1 Physical Separation
Remediation of soils contaminated with metallic
DU ty pically begins with ph ysical rem oval of
large fragments, either by hand sorting or by size
classification using a s    creening device [8   ].
Excavation and phy     sical separ  ation with

-------
screening devices may be used as the  principal
means of remediation of contaminated soil if the
contamination is associated with a particular soil
size fir  action.  Phy     sical s  eparation of
contaminated and uncontaminated soils may also
be acco mplished using   magnetic separation
technology;  or gravim etric separation  . Other
proprietary devices includ e the Seg mented Gate
System (SGS), produce   d b   y the   Eberline
Instrument Corporation, which        monitors
radiation in  soil as th   e soil m   oves along
conveyor belts and then diverts the contaminated
material  [8]  [9 ].  A   fter  separation  of the
contaminated and uncontaminated soil fractions,
the uncontaminated soils are used as cl   ean fill,
and contam inated soils are treated or processed
for disposal  . The     volume redu ction of
contaminated soil that    requires disposal or
treatment ca n result in significant cost savings
[10].

7.1.2 Chemical Extraction
Chemical extraction methods (also referred to  as
soil washing or heap leaching) use water with
various chemical additives to dissolve DU fro  m
contaminated soils. Th   e chemical   additives
include oxidants to convert relatively insoluble
U+4 to the more  soluble U +4 form, co mplexing
agents such as carbonate that increase  uranium
solubility,  and strong acids or bases  [8] [9] [10]
[11].  The  cl eaned soil is then generally used as
fill  material, and leachate containing the
uranium and other contaminants is often treated
to rem ove co ntaminants in a concentrat ed form
for disposal [8].

7.2  Groundwater Technologies
Technologies for the treatment of DU in
groundwater include:

•   Treatment of groundwater contamination by
    conventional pump and treat methods;

•   Treatment of groundwater contamination by
    permeable reactive barriers; and

•   Emerging/Pilot Studies treatments.

7.2.1 Pump and Treat
Pump and  treat  methods rem ove contam inated
groundwater from the aquifer and can be used  to
contain and  manage migration of con taminant
plumes. Pum  p and treat    methods involve
pumping contaminated water from  the groun d,
treating it, and either injecting it back into the
aquifer or di scharging it to a suitable surface
system.

7.2.2  Permeable Reactive Barriers
Permeable reactive barriers are passive systems
consisting of reactive materials placed in the
subsurface.  As groundwater flows through t  he
system, the r eactive materials in the pe rmeable
barrier remove and immobilize the contaminants
[12] [13 ]  [14  ].    Reactive m aterials used  to
remove uran ium fro m g roundwater in these
systems ty pically include  different f  orms of
metallic (zero-valent) iron [    13], but other
materials (e.g., am orphous ferric oxyh ydroxide)
have also been used to rem  ove uranium  fro m
groundwater (       www.gjo.doe.gov). A
disadvantage of using metallic iron is that the
uranium is rem oved by a precipitation reaction
and the precipitate prod uct has a tendency to
clog the bar  rier, thus reducing its 1   ong-term
effectiveness. In contrast, the use of a  material
such as apatite, a calciu m phosphate  mineral,
leads not o nly to the f  ormation of s paringly
soluble uranium phosphate minerals but also to
adsorption of uranyl carbonate complexes on the
apatite surface with little clogging.

Examples of the eff ective use of pe rmeable
reactive bar  riers to rem   ove urani um fro  m
groundwater include installations at Fry Canyon,
Utah, and Durango,                  Colorado
(www.gjo.doe.gov). A per    meable reactiv  e
barrier sy stem has also  been used to re   move
uranium from  contaminated grou ndwater in an
area known as the  mound site plu  me at DOE's
Rocky Flats  Enviro  nmental Technol ogy S  ite
(RFETS) in  Colorado [ 15]. Itisi  mportantto
note that th  e mode of  action of perm  cable
barriers 1 eaves the  contaminant in place unles s
the barrier is excavated (usually at great cost), so
barrier longevity and long-term performance are
important engineering issues.

7.2.3  Commercial Test Studies
 Several research and developm  ent (emerging)
processes have been te sted on a pilot scale  by
Water Rem ediation Technolog y, LLC , (WRT)
                                              10

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of Arvada, Colorado, using an adsorptive media
Z-92™, for treat    ment of well waters
contaminated with uranium in exces    s of the
maximum contam inant level (MCL). WRT
conducted t  hree studies at Brazos Mutual
Domestic Water in New Mexico [      16]; the
Mountain   Water &   Sanitation District in
Conifer, Colorado [17]; and the Fox R un Water
Company at Chesdin    Manor in    Dinwiddie
County, Virginia [ 18]. In each of these studies,
municipal  water  suppliers had wells that
contained water with concentrations of uranium
in excess of  the MCLs. WRT provided pilot
scale (approximately one gallon per minute) and
larger seal e  (80 gallons per  minute) sy stems
using the Z  -92™  media to dem  onstrate the
effectiveness of the tre atment process, establish
design para meters for the  full-scale systems or
document the effectiveness of the WRT system,
and meet regulator y compliance requirem  ents.
In each case, the pilot unit or larger scale system
successfully met gross   alpha and uranium
compliance at all times.

7.3  Technologies for Soil and Water
Several technologies can be used to treat either
soil or groundwater. Examples include:

•   In-situ stabilization, through the use of
    amendments, grouting, or capping of
    contaminated soil; and

•   Phytoremediation, in which plants are used
    to extract contaminants from soil or
    groundwater.

7.3.1  In-Situ Stabilization/Treatment
In-situ stabilization, treat ment, and a mendment
methods are available for immobilizing uranium
contamination in soils and gro   undwater [10].
The addition of am  endments (e.g., apatite or
phosphate solutions) stabilizes uraniu  m in soils
and gro  undwater through the for    mation of
relatively in soluble uran ium-phosphate solids
[10]   [19]   [20]. Grouting or     capping    of
contaminated soils and s ediments may also be
used to stabilize uranium contamination in place
[10]. As    with perm  cable reactive barriers,
stabilization leaves the conta mination in place.
Precipitation of uranium to the phosph ate form
leaves uranium highly insoluble and essentially
inert chem ically. Even  ingestion  would not
result in m uch uranium retention in t  he body.
Nevertheless, most methods for scree ning for
uranium would show that the uranium was still
present, and it may be difficult to be sure that the
uranium found b   y screening is effectively
stabilized as the phosphate.)

7.3.2 Phytoremediation
Phytoremediation refers t  o the utilization of
green plants'   natural absorption    of specific
components of their host  growing medium; it is
an emerging,  rather than established, technology
for remediation. Uptake of uranium by plants is
typically small      [21] [22  ].    However,
phytoremediation of urani um using sunflowers
(genus Helianthus) has been de monstrated with
uranium  waste at Ashtab ula, Ohio, a nd at a
small pond contam inated with uranium near the
Chernobyl nuclear power plant site in Pripy   at,
Ukraine [ 23]. Ph ytoremediation usin g Indian
mustard (Brassica junced) of DU contamination
at a firing    range at the Aberdeen    Proving
Ground in Maryland has also been demonstrated
[24].  Ph   ytoremediation of uran    ium is
accomplished through the process of
rhizofiltration in which plant root      s sorb,
concentrate, and precipitate metal conta minants
from surface or groundwater      [23].  The
concentration of uranium        contamination
removed from the soil by the plants can reduce
the volum e  of material that otherwise would
need be removed for disposal.

A requirem ent of  ph ytoremediation is that a
proper disp osal approach m ust be adopted for
the contaminant-bearing plants to prevent cross
media transfe r of contam inants and subsequent
exposure. F or inorgan ic contam inants such as
uranium, simply burning the plants will not
destroy the contaminant.

7.3.3 Monitored Natural Attenuation
In additi  on to t  he remediation technologies
described ab ove, the use  of  monitored natural
attenuation (  MNA)  may be  applied   as an
optional pr ocess, which should be evaluated
with other applicable remedies (including
innovative technologies) for restoring
contaminated groundwater, preventing migration
                                               11

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ofcontam  inantplum  es, and protecting
groundwater and other environmental resources.

MNA refers to the reliance on natural
attenuation process es (inc luding a variety  of
physical, chemical, or biological processes) to
achieve site -specific re  mediation objectives
within a re  asonable timefra me co mpared to
other more active methods.  In order for natural
attenuation  to be selected as a rem        edy,
determining the existence and demonstrating the
stability and irreversibility of these mechanisms
is im portant to show that a MNA rem    edy is
sufficiently  protective. Additionally, site-
specific determinations will alway  s have to be
made to ensure that    sorption capacity of the
subsurface is sufficient to be fully  protective of
human health and the environment. [25]

8.  EPA STANDARDS APPLI   CABLE
TO DEPLETED URANIUM SITES

When contaminated site  s to be released  for
public use ar e to be re mediated to  meet EPA's
media specifi c risk-based standards or criteria,
several pote ntial drivers for the re   mediation
need to be considered. Various statutes apply to
different asp ects of the   remediation process.
Table 4 lists the   major statutes that   apply to
various media  that may come into consideration
during remediation. The following sections also
provide further details of the drivers. I  t  should
be noted that the  discussion presented here is not
intended to be  comprehensive, but is provided as
a starting point for further investigation.

Table 4: Main Statutes Applying to Various  Media
in the Remediation Process.
Media                 Statute
Air
Water
Soil

Waste
CAA
SDWA
CERCLA, RCRA
NRC regulations, DOE
Orders
8.1  For Soil
Under CERCLA/RCRA, EPA's site cleanup
standards limit a person's incr   eased chance of
developing cancer to between 1 in 10,000 and 1
in 1,00 0,000 fro m resid ual uranium on the
ground [26]. Site-specific factors are weighed in
establishing the actual clean up value.

8.2  For Air
Under the CAA, EPA established the amount of
uranium in t he air as the  maximum d ose to an
individual not to exceed   10m illirems (mrem)
per year [27].

8.3  For Water
Pursuant to  the SDWA,  EPA establ  ished an
MCLofSO   micrograms per liter (    :g/L) for
uranium in drinking water [28].

8.4  Storage of Depleted Uranium
DU is not stored widely around the country; the
majority of the inventor  yofDUis    stored at
United States Enrichm ent Corporation (USEC)
sites or at DOE sites.  DU stored  by the military
is only a fraction of the to tal. It should be noted
that under the Ato  mic Energy Act (AEA), the
storage of depleted uranium     hexafluoride
(DUF6) is self-regulated by  the  DOE.  DUi   s
mainly stor  edinthe     form  of uranium
hexafluoride (UF 6), whic h is a colorl  ess high
molecular  weight (352) solid, at a      mbient
temperature. It is readily transformed into a gas
at at  mospheric pres  sure by  raising its
temperature above  56.5°C, and into a 1  iquid by
increasing the pressure and tern  perature above
1.5 atm ospheres  and 64 °C. All thre  e phases,
solid, liquid and gas, coexist at 64°C

A2001joi  nt report b y the  Organization for
Economic Cooperation     and  Developm   ent
(OECD)  Nuclear Energ  y Agenc y  and the
International Atom  ic Energy  Agency     on
Management of Depleted Uraniu  m noted that
DU arising  from  the operations of enr  ichment
plants can be safely stored in different form  s,
including uranium tetrafluoride (UF     4), or
uranium oxides (U3O8, UO2, and UO3)  in  coated
steel contain ers in extern al y ards, provided that
contact with standing water is prevented and that
containers are  routinely inspected and  localized
defects leading to corrosion are treated. [29]
                                              12

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8.5 For Disposal
For purposes of disposal, DU is    cons idered a
low-level waste (LLW) and its di      sposal is
subject to U.S. Nuclear R egulatory Commission
(NRC) regulations and appropriate DOE Orders.
Disposal of DU mixed  waste having both a
radioactive com ponent and a RCRA hazardous
waste co  mponent m  ust be performed in
compliance  with NRC LLW requirements and
RCRA hazardous waste requirements.

The Executive Summary of the DOE, Oak Ridge
National Laboratory's Assessment of  Preferred
DU Disposal  Forms pub  lished in Ju  ne 200 0
noted t hat ". . .the four  p otential form s of DU
(DU metal, DUF 4, DUO 2, and DU 3O8) in this
study should be accepta   ble for   near-surface
disposal at si tes such as t he Nevada  T est Site
(NTS) and  Envirocare."  [30]. It further added
that, "The DU products   are considered to   be
low-level waste under bo   th DOE ord ers and
NRC r egulations." It indicated the pr  eference
for disposal at "...the NTS  because of its unique
geohydrologic and institu tional settings." The
study also noted that, "Each DU fo     rm has  a
degree of un certainty reg arding DUF 4, DUO 2,
and DU3O8 acceptability [for disposal  at NTS ],
with the unce rtainty decreasing in the following
order: DU metal, DUF4, DUO2, and DU3O8 [30]

EPA has issued guidance entitled
"Establishment of Cleanup Levels for C ERCLA
Sites with   Radioacti   ve Contamination"
(OSWERNo. 920 0.4-18, August 22  ,1997)
which provi ded clarification for establishing
protective cleanup levels for radioactive
contamination at CERCLA sites. The   guidance
reiterated that cleanups of radionuclides are
governed b y the risk range for all   carcinogens
established i n the National Oil and Hazardous
Substances Pollution Cont ingency Plan (NCP)
when applicable or re   levant and appropriate
requirements (ARARs) are not available or are
not sufficient!  y protecti  ve. Cleanup should
generally achieve a level  of risk within the 10 "4
to 10 "6 carci nogenic risk range based on t    he
reasonable maximum exposure for an individual.
In calculating cleanup levels, one shoul d include
exposures from  all potential pathway   s, and
through all  media (e.g., soil,      groundwater,
surface water, sediment, air, structures, etc.) To
assist with calculating risk, EPA has developed a
Superfund radionuclide preliminary remediation
goal (PRG) calculator. PRGs for the Superfund
programs are risk-based concentrations, derived
from standardized equations co        mbining
exposure information assum ptions with EPA
toxicity data. They    are considere   d to be
protective for hum  ans, thou  gh n  ot alway s
applicable to a particular site and they   d o not
address non-hum an healt h endpoi nts such as
ecological im pacts. PR Gs ar e used  for site
"screening" and as initial cleanup goals if
applicable. PRGs are     not actuall y cleanup
standards and should  not be applied as such.
Their role in site "screening" is to  help identify
areas, contaminants, and conditions t  hat do not
require further federal art ention at a particular
site. Additionally, the   y could   be used to
establish final cleanup levels for a   site after a
proper evaluation takes place. In the S uperfund
program, this evaluation is carried out as part of
the nine criteria for remed y selection outlined i n
the National Oil and    Hazardous Su bstances
Pollution Contingenc y PI an (NCP). Once the
nine criteria analysis is completed, the PRG may
be retained  as is, or  modified (based on site-
specific inf  ormation) prior to beco      ming
established as a cleanup standard.
                                               13

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                                       Acronyms

AEA   Ato          mic Energy Act
ALI             Annual Limits on Intake
ARAR          Applicable or Relevant and Appropriate Requirements
ATSDR         Agency for Toxic Substances and Diseases Registry
CAA   Clean           Air Act
CERCLA        Comprehensive Environmental Response, Compensation, and Liability Act
DOE   Department           of Energy
DU    Depleted           Uranium
EPA            U.S. Environmental Protection Agency
ISCMEM        Interagency Steering Committee on Multimedia Environmental Models
LLW   Low-Level          waste
MARLAP       Multi-Agency Radiological Laboratory Analytical Protocols
MARS SIM      Multi-Agency Radiation Survey and Site Investigation Manual
MCL   Maxim          um Contaminant Level
MNA  Monitored          Natural Attenuation
NCP            National  Oil and Hazardous Substances Pollution Contingency Plan
NRC   Nuclear          Regulatory Commission
NTS   Nevada          Test Site
OECD          Organization for Economic Cooperation and Development
OSC   On-Scene          Coordinators
OSWER         Office of Solid Waste and Emergency Response
PRG   Preli           minary Remediation Goal
RCRA          Resource Conservation and Recovery Act
RFETS          Rocky Flats Environmental Technology Site
RPM   Remedial          Project Managers
SDWA          Safe Drinking Water Act
SGS   Seg          mented Gate System
SSL    Soil           screening Levels
TDI    Tolerable          Daily Intake
USEC United           States Enrichment Corporation
WHO  World           Health Organization
WRT            Water Remediation Technology, LLC
                                            14

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                                           Glossary

Alpha particle - A positively charged particle made up of two neutrons and two protons emitted by
certain radioactive nuclei. Alpha particles can be stopped by thin layers of light materials, such as a sheet
of paper, and pose no direct or external radiation threat; however, they can pose a serious health threat if
ingested or inhaled.

Becquerel (Bq) - The international, or SI, unit used to measure radioactivity, equal to one transformation
(or disintegration) per second. Often radioactivity is expressed in larger units like: thousands (kBq), or
millions (MBq) of Becquerels. One Curie (the traditional activity unit) is equal to 3.7 x 1010 (37 billion)
Bq.

Beta particle - An electron or positron emitted by certain radioactive nuclei.  Beta particles can be
stopped by aluminum. They can pose a serious direct or external radiation threat. They also pose a
serious internal radiation threat if inhaled or ingested.

Curie (Ci) - A traditional unit used to measure  radioactivity.  One Curie equals that quantity of
radioactive material in which there are 3.7xl010 nuclear transformations per second. The activity of 1
gram of radium-226 is approximately 1 Ci.

Depleted uranium - Uranium containing less than 0.7% uranium-235, the amount found in natural
uranium. (See also enriched uranium)

Enriched uranium - Uranium in which the proportion of the isotope uranium-235 has been increased.
(See also depleted uranium.)

Gamma rays - High-energy electromagnetic radiation emitted by certain radionuclides when their nuclei
transition from a higher to a lower energy state. These rays have high energy and a short wavelength.
Gamma rays are very similar to X-rays.

Half-life - The time in which one-half of the atoms of a radioactive isotope disintegrate into another
nuclear form. Half-lives vary from  billionths of a billionth of a second to billions of years.  Also called
physical or radiological half-life.

Ion - An atom or molecule that has too many or too few electrons, causing it to have an electrical charge,
and therefore, be chemically active.

Isotope - A nuclide of an element having the same number of protons but a different number of neutrons.

Maximum contaminant level (MCL) - The amount of a contaminant that may be present in drinking
water under the Safe Drinking Water Act. MCLs are the standards that drinking water treatment systems
must meet.

Microcurie (\iCi) - One-millionth of a Curie. (3.7xl04 disintegrations per second.)

Molecule - A combination of two or more atoms that are  chemically bonded. A molecule is the smallest
unit of a compound that can exist by itself and retain all of its chemical properties.

Monitoring - The use of sampling  and detection equipment to determine the levels of radiation or other
toxic materials in land, air, or water.
                                               15

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Millirem (mrem) - One-thousandth of a rem.

Neutron - A small particle possessing no electrical charge typically found within an atom's nucleus. A
neutron has about the same mass as a proton.

Nuelide - A general term applicable to all atomic forms of an element. Nuclides are characterized by the
number of protons and neutrons in the nucleus, as well as by the amount of energy contained within the
atom.

Oxide - A compound formed by the reaction of oxygen with another element. For example, rust - ferrous
oxide - is iron that has combined with oxygen.

Picocurie (pCi) - One one-millionth of a microcurie (3.7xlO~2 disintegrations per second).

Proton - A small particle, typically found within an atom's nucleus, that possesses a positive electrical
charge.  The number of protons is unique for each chemical element.

Rad - (See Radiation Absorbed Dose)

Radioactive decay - The process in which an unstable (radioactive) nucleus emits radiation and changes
to a more stable nucleus. A number of different particles can be emitted by decay. The most typical are
alpha, beta and gamma particles.

Radioactivity - The process  of undergoing spontaneous transformation of the nucleus, generally with the
emission of alpha or beta particles, often accompanied by gamma rays.

Radioisotope - An isotope of an element that has an unstable nucleus. Radioactive isotopes are
commonly used in science, industry, and medicine. The  nucleus eventually reaches a more stable number
of protons and neutrons through one or more radioactive decays. Approximately 3,700 natural and
artificial radioisotopes have been identified.

Radionuclide - An unstable  form of a nuclide.

Rem - (See Roentgen Equivalent Man)

Roentgen Absorbed Dose (rad) - A basic unit of absorbed radiation dose. It is being replaced by the
"gray," which is equivalent to 100  rad.  One rad equals the dose delivered to an object by 100 ergs of
energy, per gram of material.

Radiation Equivalent Man (rem) - A unit of equivalent dose. Rem relates the absorbed dose in human
tissue to the effective biological damage of the radiation. Not all radiation has the same biological effect,
even for the same amount of absorbed dose.

Specific activity - The activity of radioisotope per unit mass of a material, either (a) in which the
radioisotope occurs, or (b) consisting of only that isotope.

Treatment - A 'treatment' technology means any unit operation or series of unit operations that alters the
composition of a hazardous substance, pollutant, or contaminant through chemical, biological, or physical
means so as to reduce toxicity, mobility, or volume of the contaminated material being treated.  See
Appendix 7 for complete definition.
                                               16

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Uranium - A naturally occurring radioactive element whose principal isotopes are uranium-238 and
uranium-235. Natural uranium is a hard silvery-white shiny metallic ore that contains a minute amount of
uranium-234.

X-rays - High-energy electromagnetic radiation emitted by atoms when electrons fall from a higher
energy shell to a lower energy shell. These rays have high energy and a short wave length.  X-rays are
very similar to gamma rays.
                                              17

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                           Additional Sources of Information
The following reports, documents, and websites offer additional information about DU:
Argonne National Laboratory. Depleted Uranium, Human Health Fact Sheet. October 2001.
Argonne National Laboratory. Depleted UF6 Management Information Network.
http: //web. ead. anl.gov/uranium/
International Ato mic En ergy Agenc y. Depleted  Uranium Fact Sheet. International Atom   ic Energy
Agency Information Series, Division of Public Information, 01-01198 / FS Series 3/02/E.
North Atlantic Treaty Organization. NATO Information: Depleted Uranium.
http: //www .nato. int/du/home .htm
The Royal Society. The Health Hazards of Depleted Uranium in Munitions. Policy Document 7/01. May
2001.  Available at http://www.royalsoc.ac.uk/
U.S. Department of Defense. Deployment Health Support, http://www.deploymentlink.osd.mil/
U.S. Department of Energ y, Office of Envir  onmental Managem ent, Depleted Uranium Hexafluorid e
Management Program. Depleted Uranium Hexafluoride Fact Sheet. Washington, DC. Fall 2001.
U.S. Department of Energy   , Office of Enviro   nmental Man agement and Office of    Technology
Development. Depleted Uranium: A DOE Management Challenge. Washington, DC. October 1995.
U.S. Department of Energy, Office of Nuclear Energy, Science, and Technology. Final Programmatic
Environmental Impact Statement for Alternative Strategies for the Long-Term Management and Use of
Depleted Uranium Hexafluoride. April 1999.
http: //web. ead. anl. gov/uranium/documents/nepacomp/peis/index.cfm
U.S. Environmental Protection Agency. EPA Facts About Uranium. July 2002.
http: //www .epa. gov/superfund/re sources/radiation/pdf/uranium .pdf
U.S. Environmental Protection Agency. Soil Screening Guidance for Radionuclides: Technical
Background Document.  Office of Radiation and Indoor Air, EPA/540-R-00-006.  OSWER Directive
9355.4-16.  October 2000. http://www.epa.gov/superfund/resources/radiation/radssg.htm
U.S. Environmental Protection Agency. Soil Screening Guidance: A User's Guide. OSWER 9355.4-16A.
October 2000.
U.S. Environmental Protection Agency. Common Radionuclides Found at Superfund Sites. OSWER
9200.1-34.  July 2000. http://www.epa.gov/superfund/resources/radiation/pdf/nuclides.pdf
U.S. Environmental Protection Agency. Field Demonstration of Permeable Reactive Barriers to Remove
Dissolved Uranium from Groundwater: Fry Canyon, Utah, September 1997 through September 1998
Interim Report. Air and Radiation Emergency Response. EPA 402-C-00-001.  November 2001
World Health Organization, Departm  ent of Protection of the Human Environment.   Depleted Uranium:
Source, Exposure, and Health Effects. Geneva, April 2001.
Nuclear Energ y Agenc y, Organization for Econ omic Cooperation and  Development; Environm ental
Remediation of Uraniu m Production Facilities, A joint report by the OECD-NEA  and the International
Atomic Energy Agency (IAEA).
National Research Council. Evaluation of Guidelines for Exposure to TENORM. 1999. Pgs. 33, 34, & 76.
                                             18

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       Appendix 1: Technical Background on Uranium and Depleted Uranium

Origin and History
After the discovery of fission, it was realized that to produce a practical military weapon, the much rarer
isotope of 235U would have to be separated from  the much more common 238U isotope. In  the United
States, massive efforts were undertaken, as part of the Manhattan Project, to produce uranium enriched in
235U.

Enrichment is a process t hat increases the amount of one isotope relative to another.  Regardless of the
enrichment method utilized for uranium, large quantities of uranium depleted in 235U, are generated as a
waste product. This waste became known as depleted uranium, or DU.

Production of highly enriched uranium (HEU) ended in 1992 due to the decreased needs of U.S. defense
programs. In 1993, the United States Enrichment Corporation assumed responsibility for the production
of low-enriched uranium (LEU) for commer  cial nuclear reactor fuel. As a re suit of past enrich   ment
activities, DOE currently maintains a large  inventory of DU, most of it stor  ed in the for m of uraniu m
hexafluoride. Smaller quantities of DU are stored  in the form of uranium metal, uranium metal alloys,
and uranium oxides.

Uses of Depleted Uranium
The most well known use  for DU is in the manufactu  re of armor-piercing projectiles  due to its high
density and pyrophoric properties. It is also used for other military purposes to reduce the effect of other
conventional munitions.  Civil applications are also prevalent, including use in counterweights in aircraft,
missiles, racing sailboat keels, and as a material used in hospitals for shielding X-rays or gamma radiation
from equipment used for radiation therapy. Below are further discussions of some of these applications.

Further Enrichment
DU was once proposed as a feedstock for further ur    anium en richment. T his application has been
postponed indefinitely because of the present low co stof uranium ore. It should be noted t  hat, like the
initial enrichment process, any further enrichment of DU would result in sm all quantities of "enriched  "
uranium and about the same amount of DU.  The  DU would contain an even  sm aller proportion of 235U
than the original DU.

Nuclear Reactor Fuel
While DU cannot be used directly in nuclear reactor fuel, it can be used as a fer tile material in a breeder
reactor to pr oduce plutonium -239 (239Pu). The plutonium  , once extracte d, can be blended with DU to
make mixed oxide (MOX) reactor fuel (typically 6% Pu and 94% DU).

Down-blending  Highly Enriched Uranium
DU could be blended with weapons grade highly enriched uranium (HEU) to make co  mmercial reactor
fuel. This o ption is one method to reduce the qua ntity of HEU, as part of a reduction in   the nuclear
weapons stockpile.

Munitions
DU metal has been used  in conventional  military applications, most notably in tank armor and arm  or-
piercing projectiles.  Conventional weapons using DU were used in the 1991 and 2003 Gulf Wars and in
NATO operations in Kosovo and Bosnia.

Shielding
                                              19

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The high atomic number (Z=92) and hi gh density (19.5 g/cm3) make DU an excellent potential material
for shielding persons or equipment from X-rays and gamma rays.

Counterweights
The high density that, in part,  makes uranium such an attractive shielding material also makes it suitable
as a small but heavy counterweight in aircraft and other similar applications.

It should  be noted t hat Military S pecification MIL-U-70457 s tipulates that DU used by the U.S
Department of Defense (DoD) must have a 235U concentration of less than 0.3% by weight.  Most DU has
a 235U concentration of a pproximately 0.2% by weight. In ad ditionto 234U, 235U, and  238U, DU may
contain trace amounts of 236U. The detection of 236U indicates that part of the depleted uranium originated
from reprocessed uranium.

To date, the above uses of  DU have  consumed only a small portion of the DU in storage.  A number of
other uses for DU have b een proposed, so me of wh ich might result in the consu mption of a significant
amount of the stored DU. Additional proposed uses include the following.

High-Density DU Shielding
DU metal has been used in som e shielding applications, but the high cost of converting UF6 to metal has
prevented more widespread use.  One proposal being considered is to incor porate DU into concrete for
applications in self-shielded storage boxes for radio  active waste and dry  spent fuel storage  shields for
onsite storage of civilian reactor fuel.

Cask Fill Material, Repository Inert Material, or Back Fill Material
Depleted UO2 has been proposed for use as a fill   material in spent fuel nuclear waste cont ainers. The
concept is in tended to provide add  itional shielding, reduce the 1 ikelihood of criticality  accidents, and
reduce the lo ng-term release of radionuclides.  Fo  r sim ilar reasons, DU has also been proposed as a
repository inert or backfill material.

Counterweights for Forklift Trucks
Use of DU metal, clad in protective  steel shielding, in fork lifts as counterweights would result in th  e
design of forklifts that co uld lift heavier loads, whi le at the same time reduce the turning radius of the
forklift.  This would allow the forklift t o work i n narrower aisles, increasing the usable warehouse floor
space.

Depleted Uranium and  its Chemical Forms
DU can exist in any  chemical form in which uraniu m occurs.  Since all isot opes of an element undergo
the sam e reactions in nat ure and have  aim ost identi cal phy sical characteri sties, natural, enriched and
depleted uranium are essentially chemically identical. Each  isotope has the sa me chemical reactions in
the environment, and the sam e biochemical and biol ogical effects on the hu  man body. Any differences
exist because of small mass differences between various isotopes.

Chemically, DU is identical to "norm al" uranium. Uranium is the heaviest existing  natural element and
can react with most elements except rare gases. In the air, it forms oxides such as uranium oxide  (U O2)
and triuranium octaoxide (U3O8). At room temperature, humidity can promote the oxidation of uranium.
When uranium is fragmented in      chips, powder, and turnings, the     metal beco mes py rophoric,
spontaneously ignites in a ir. Uranium  is produced i n a num ber of chemical  forms, including uranium
oxides, uranium  h exafluoride, uranium tetrafluorid e, and uranium   metal. T  hese for ms a re explaine d
below in  greater detail. T he physical properties of s ome of the m ost important uranium compounds are
given in Table 5.
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Uranium Oxides
Uranium oxides include U3O8, UO2, and uranium trioxide (UO3).  Both U3O8 and UO2 are solids that are
relatively stable over a wi de range of environm ental conditions, with a low so lubility in water.  In these
forms, the DU is chemically more stable and suitable for long-term storage or disposal. U3O8 is the most
stable form of uranium and is the form most commonly found in nature. The most common form of U3O8
is "yellow cake," a solid produced duri ng mining and milling operations, and named for its characteristic
yellow color. UO 2 is a solid cera mic material, and the form of uranium most commonly used in nuclear
reactor fuel. At ambient temperatures, UO2 gradually converts to U3O8.
Uranium Hexafluoride
Uranium hexafluoride is t he chemical form of uranium  used during enrichme nt. UF 6 can be a  solid,
liquid, or gas within a reasonable range  of temperatures and pre ssures. SolidUF6isa white, dense,
crystalline material, resem bling rock salt. While UF  6 does not react with ox  ygen, nitrogen, carbon
dioxide, or dry air, it does react with water or water vapor to form corrosive hydrogen fluoride (HF) and
uranyl fluori de (UO 2F2). Becaus e UF 6 reacts with water, inclu ding hum idity i n the air, it is alway  s
handled in leak-tight containers or processing units.  Although  very convenient for processing, UF6 is not
favored as a chemical form for long-term storage or disposal because of its relative instability.

In uranium conversion and enrichment processes, a major hazard is the handling of uranium hexafluoride
(UF6), which is che mically toxic.  Uranium  in thes e situations can also react  with moisture to release
highly toxic hydrofluoric acid.

Uranium Tetrafluoride
Uranium tetrafluoride (UF 4), sometimes called green salt bee ause of its char acteristic green color,  is a
solid com posed of aggl  omerating particles with a te xture sim ilar to baki ng soda. It  is nonvolatile,
nonhydroscopic, and slightl  y soluble   in water.   When exposed to water, UF  4 slowly dissolves a nd
undergoes hydrolysis, forming several possible uran ium compounds and hydrogen fluoride (HF). UF4 is
generally an intermediate in the conversion of UF6 to uranium oxide (UO2 or U3O8) or uranium metal.

Uranium Metal
Uranium metal is  among the densest materials known, with a den sity of 19 gr ams per cubi c centimeter
(g/cm3). The silvery  white, malleable, and ductile metal is not  as stable as uranium oxide and will
undergo surface oxidation. It tarnishes in air, with the oxide     film preventing oxi dation of the bulk
material at room temperature. Uranium metal powder or chips will ignite spontaneously in air at ambient
temperature.

Manufacturing/Enrichment Processes
To produce uranium for commercial reactor fuel or military applications, the uranium must first be mined,
milled, enriched, and converted to a usable form .  Uranium ore contains about 0.1% uranium by weight.
This ore is processed at mills using mechanical and chemical measures to separate the uranium fro m the
remainder of the ore. The uranium mills produce "yellow cake," a powder containing mostly U3O8.

Since isotopes of the same element have the same chemical properties, enrichment must be accomplished
by using processes that are based on the phy sical differences between isotopes, such as mass. A number
of methods have been developed to enrich uranium  , including gaseous diff usion, gas centrifuge, and
electromagnetic separation .  In gaseous diffusion,   enrichment is acco mplished by first converting the
yellow cake (U3O8) into uranium hexafluoride (UF 6), a highly corrosive gas. This gas is allowed to pass
through a porous barrier,  where the lig hter 235U  molecules  are slightly m ore li kely to pass through the
barrier than t he heavier  238U molecules.  Be cause 235UF6 and  238UF6 molecular w eights  ar e nearly the
                                              21

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same, the gas is only slightly enriched in a single stage. The gas is passed through m any stages, until the
235U fraction in the  gaseous UF 6 is increased to the required enrich  ment.  In addition to t  he enriched
uranium produced, a large quantity of DU, containing about 0.2% 235U, is also generated as a byproduct.

Some of this DU has be en used to manufacture armor-piercing penetrators and armor.  Army contractors
manufacture penetrators  from DU metal  at contractor-owned, contractor-operated facilities.   The U.S  .
Nuclear Regulatory Commission (NR C) and Agre ement States license these  contractors to possess an d
store DU and to manufacture munitions components from  it.  A typical license would allow a contracto r
to receive depleted UF6, transport it to a manufacturing facility, convert it into UF4 and/or metal, and sell
the DU components to an authorized buyer.  Most of the depleted uranium hexafluoride (DUF6) is stored
in cylinders at the gaseous diffusion plants where it was generated.

USEC was created as  a government corporation to shift some of the enrichment capacity from military to
civilian use. In the early  1990s, USEC was created as a government co rporation that became USEC, Inc.
when it was privatized in 1998. Today, USEC, Inc.  is the world's leading supp Her of enriched uranium
fuel for co mmercial nucle ar plants. T hey currently manage  enri chment proce sses out of the Paducah,
Kentucky, plant and perform research and laboratory functions out of the Portsmouth, Ohio plant.

DUF6 can be stored in three for  ms-liquid, gaseous , or solid. At a mbient tern peratures and pressures
DUF6 is a solid; therefore, it is not easily released from the  storage container. When DUF6 mixes with the
water vapor in the air and the iron oft he cylinders, a plug of soli d uranium and iron com pounds and a
small amount of HF gas is created, limiting the amount of material released from a breached cylinder.

Most of DOE's DU inventor y contains between 0.1 to 0.4 weight-percent uranium -235, in the form  of
uranium hex afluoride (UF 6) or uraniu m tetra-fluoride (UF 4), well below levels neces  sary to create a
nuclear chain reaction. A  large stockpile has  been contained pri marily in the  form of UF 6 i n metal
cylinders stored at DOE's enrichment facilities. DU manufacturing and testing facilities in  the United
States are provided in App endix 4, while Appendix 3 contains a listing of sites  on the NPL that have or
may have DU contamination.
Table 5: Physical Properties of Uranium Compounds
Compound
                       Melting Point (°C)
   Density (g/cm )
                                              Crystal
                                              Particle
                                                           Bulk
        Solubility in Water at Ambient
        Temperature
Uranium Hexafluoride
(UF6)                  64.1

Uranium Tetrafluoride
(UF4)                  960 ± 5
                                                                   Decomposes to UO2F2
                                              4.68


                                              6.7
             4.6
             2.0-     Very Slightly Soluble
             4.5
Uranyl Fluoride (UO2F2)  Decomposes to U3O8 at
                       300                    6.37

Triuranium Octaoxide     Decomposes to UO2 at
(U3O8)                 1,300                  8.30
                                                                   Soluble
                                                            -2.6
Uranium Dioxide (UO2)


Uranium Metal (U)
                       2,878 ± 20

                       1,132
10.96

19.05
1.5-     Sparingly Soluble
4.0

2.0-     Sparingly Soluble
5.0

19      Sparingly Soluble
Source: http://web.ead.anl.gov/uranium/guide/ucompound/propertiesu/tablephysprop.cfm
                                               22

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            Appendix 2: Measurement Tools and Monitoring Techniques

Monitoring uranium in the environment includes both field measurements and analysis of environmental
samples in the laborator  y. Since there is consid  erable natural uranium  around in all soi Is and the
concentration of natural uranium varies greatly, analyses for uranium alone may not tell anyone if DU is
present, and so isotopic analyses are generally needed. This is also important since, although there is little
difference between the hazard from natural uranium and that from DU, there could be serious legal issues
when a site could be responsible for the DU, but not  for the natural uranium. DOE has had c ases where
the total uranium present could have been either background or from leaks or emissions.

The following sections provide some introductor  y i nformation o n measurement tools and m  onitoring
techniques used for uranium . It should also be noted that EPA has recently  published an inventor y of
radiological methodologies for sites contaminated with radioactive materials (see reference 4 on page 9)
and the interested reader is referred to this document for further information.

Field Measurements
Field m easurements are typically perfor med using ha nd-held survey m eters, capable of detecting alpha
particles while discriminating against be ta particles.  These instruments ty pically provide an esti mate of
the surface  contam ination due to all alpha em   itting radionuclides present.   Alpha scintillation (ZnS)
detectors have been commonly used in the past,  but large-area gas-flow proportional counters have often
been found to be more suitable for remediation efforts where lower detection limits are required [1].

The Measurements Applications and Development   Group at Oak Ridge National Laborator y (ORNL)
compared th e perfor mance of sever al hand-held de tectors co mmonly used to detect DU   in soil [45 ].
Detectors rev iewed included a Fi eld Instru ment fo r Detection of Low Energy  Radiation (FIDLER), a
1.25"x  1.5" sodium iodide (Nal)  detector, and o pen and closed window pancake-type detectors.  The
open-window pancake detector showed the best dete  ction sensitivity, although the Nal detector s ystems
provided more consistent results.

Field measur ements using survey m  eters are best   suited for  ide ntifying surface conta mination.  The
detection of DU below the surface usi ng hand-held proportional counters, ioni zation chambers, and GM
counters is inhibited by the absorption of alpha and  beta particles in the soil. Hand-held gamma ray
spectrometers can detect DU below the surface, but   the lack of a high-energy   , high-yield gamma-ray
emission b y 238U  significantly reduces the effective  ness of th is technique for field identification and
survey [46].

Laboratory Analysis of Environmental Samples
A num ber of analy tical methods have  been develop ed to quantif y uranium in environm ental sam pies.
Environmental media that have been   analyzed include air filters, swipes, bi  ota, water, and soil  [  1].
Analytical methods inclu de both chemical  methods that usuall y determ ine onl y t he total quantit y of
uranium, and  radiological  methods that can determ  ine the quantit  yofind ividual urani um isotopes.
Chemical methods include kinetic phosphorescence analysis, X-ray fluorometry, and mass spectrometry.
Among the most common radiological methods are alpha spectrometry, gamma ray spectrometry, delayed
neutron counting, and i  nstrumental neutron activa tion anal ysis. These methods are briefly described
below.

Kinetic Phosphorescence Analysis (KPA)
KPA is a  method that us es a laser to  excite uran ium in an aq  ueous solutio n and then  measures the
emission luminescence intensity overtime.  The intensity of the luminescence is proportional to the total
                                              23

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quantity of uranium in the sam pie. The technique  provides no information about the relative isotopic
abundances of uranium and, therefore, cannot distinguish DU from natural uranium in the sample.

X-Ray Fluorometry (XRF)
XRF is si milar to KP A, but uses X-ra ys to excite secondar y X-ray fluorescence in the sam pie material.
The secondary X-rays have wavelengths characteristic of the element that produced them. The X-rays are
separated by wavelength  by Bragg diffraction in a  crystal with the appr opriate lattice sp acing. The
measurement of the intensity   oft he X-ray s at  the characteri  stic wavelen gth provi des quantitative
information  about trace elem ents in th e sample material, including uranium .  XRF does   not provide
information about the isotopic composition of the uranium in the sample.

Mass Spectrometry (MS)
MS is a technique that separates and analyzes ions based on the ratio of the  mass to the charge. Unlike
most chemical methods, this method provides quant itative information about both the tot  al quantity o f
uranium in the sam  pie and the isotopic co  mposition. The two  most common MS techniques for
quantification of uranium in environmental samples are thermal ionization mass spectrometry (TIMS) and
inductively coupled plasma-mass spectrometry (ICP-MS). Until r ecently, TIMS had been  t he preferred
method for the determination of uranium isotopic ratios in environmental samples because of its superior
sensitivity, a ccuracy, and precision, but ICP-MS    has been sh own to provide si   milar accuracy and
precision, with higher sample throughput and ease of use [46].

Alpha Spectrometry
Alpha spectrometry is a method that relates the q uantity of a given alpha-emitting radionuclide to the
number of alpha particles detected .  Since radionuclides emit  alpha particles  at one or   more discrete
energies, it is possible to relate the area of a peak in the alpha spectrum to the quantity of a radionuclide in
the sample. Alpha particles continuously lose energy to the electrons in the medium they are traveling in,
and will travel only a short distance before they lose all their energy.  For this reason,  samples should be
kept thin and placed near the detector.

Gamma Spectrometry
Gamma spectrometry  involves the det  ection of ga mma ray s emitted by radionuclides. Radionuclides
typically em it gamma ray  s at one or   more discret e energies.   The area s of peaks in the ga mma ray
spectrum can be related t  othe quantity of the app ropriate radionuclide.   Si nee different isotopes of
uranium emit gamma ray s of different energies, gamma spectrometry can be used to quantify the relative
abundance of uranium iso topes in addi tion to the t otal quantity of uranium .  Unlike alp ha particles,
gamma rays can penetrate soil and water, and can be detected some distance from the source.

Instrumental Neutron Activation Analysis (INAA)
INAA involves the irradiation of a sample with neutrons to produce an activation product that decays by
emission of gamma rays characteristic of the radionuclide. After irradiation, the sample is  counted using
a high resolution gamma ray spectrometer.  For DU, the radionuclide  of interest is 238U, which absorbs a
neutron to become 239U.   239U emits gamma radiation when it decays to ne ptunium-239 (239Np). As
mentioned in the previous  section, INAA can be used with delayed neutron counting to m easure both the
isotopic composition and the total quantity of uranium in the sample.

Delayed Neutron Counting (DNC)
DNC is a  method for determ ining the quantit y of  235U and other fissile radionuclides in a sample by
irradiating the sample with neutrons an d counting the delayed neutrons from fission.  Delay ed neutrons
result from a small fraction of fission products that emit neutrons  as part of their decay chain. DNC can
be used with instrumental  neutron activation analy  sis, described previously, to deter mine the isotopic
composition of uranium, which is necessary to distinguish DU from natural uranium.
                                              24

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Analytical Methods for Air Samples
Air samples are typically collected on so me type of air filter and then analy zed by one oft he methods
described previously, including ICP-MS, alpha spectrometry, or INAA.

In a method used b y EPA's National Air and Radi  ation Enviro nmental Lab oratory (NAREL), the air
filters are  ashed, silica  content is volatilized wi   th hy drogen fluoride, uranium is    extracted with
triisooctylamine, purified by anion exc hange  chroma tography, and co-precipi tated with lanthanum as
fluoride.  The uranium is then collected by filtration and dried. The activities of 234U, 235U, and 238U are
measured by alpha spect  rometry. T his method is u sed to measure urani um in air as part of the
Environmental Radiation Ambient Monitoring  System [47].

In another method, described by Singh and Wrenn, air filters are ashed, re-dissolved, and co-precipitated
with iron hydroxide and calciu  m oxalate.  The uranium  is further purified by   solvent ext raction and
electrodeposition. A det  ection level of 0.0 2dpm/Lfor  238U in solutio  n was reported using alpha
spectrometry [48].

Analytical Methods for Water Samples
EPA's Env ironmental and S  upport Laborator y pub lished  standardized procedures in    1980 for
measurement of radioactivity in drinking water that included uranium analysis by both radiochemical and
fluorometric methods [49], and more recently, developed an ICP-MS method.

In the radiochemical method, the uranium is co-precipitated with ferric hydroxide, purified through anion
exchange chromatography, and converted to a nitrate  salt.  The re sidue is transferred to a stainless ste el
planchet, dried, and flamed. T he gross alpha  activit y is m easured using either a gas flow  proportional
counter or a scintillation detection system following the chemical separation [49].

For the fluor ometric method, uranium is concentrat ed by  co- precipitation with alum inum phosphate,
dissolved in diluted nitric acid containing  magnesium nitrate as a salting agent, with the  co-precipitated
uranium extracted into ethyl acetate, and dried. The uranium is dissolved in nitric acid, sodium fluoride
flux is added, and the samples fused over a heat source [50].

The ICP-MS  method was developed f or measuring tota 1 uranium in water  and waste.   The sample
preparation is minimal - filtration for dis solved uranium, followed by  acid digestion for total recoverable
uranium. Recovery is quantitative (near 100%) for a variety of aqueous and solid matrices and detection
limits are low, 0.1 :g/L for aqueous samples and 0.05 mg/kg for solid samples [51].

Analytical Methods for Soil Samples
EPA's Office of Radiation and Indoor Air has  developed two  methods for the radiochem ical analysis of
uranium in various environmental media including soil: a fusion method and a non-fusion method [47]. In
the fusion method, the sa mple is ashed, the silica  volatilized, the sample fused with potassiu m fluoride
and pyrosulphate, a 236U tracer added, and the uranium  extracted with triisoocty lamine, purified on an
anion exchange colum n, co-precipitated with lantha num, filtered, and prepared in a planchet. Alpha
spectrometry is used to    quantify the individual ur anium  i sotopes,  and the sa  mple  concentration is
calculated using the 236U yield.

In the non-fusion method, the sample is ashed,  the silica volatilized, a 236U tracer  added, and the uranium
extracted with triisooctylamine, stripped with nitric acid, co-precipitated with lanthanum, and transferred
to a planchet. Further analysis by alpha spectrometry is the same as that for the fusion method.
                                              25

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Table 6: Selected Analytical Methods for Determining Uranium in Environmental Samples
        (see Table 6-2 of the Toxicological Profile for Uranium [1] for additional methods and details)
Sample Matrix
Water

Water



Water


Water

Groundwater







Groundwater




Soil



Soil



Soil,
sediment,
and biota


Soil,
sediment,
and biota

Sample Preparation
Sample fusion with sodium fluoride (NaF)
and lithium fluoride (LiF)
Pre-concentration by ion exchange
chromatography; purification by ion-
exchange and solvent extraction

Extraction by ion-exchange; dissolution in
low oxygen solvent; irradiation

Wet-ashed; reaction with complexant

Separation on resin; automated








Separation and concentration on two High
Performance Liquid Chromatography
(HPLC) columns; complexation with
Arsenazo III
Dissolution in HC1-HNO3 -HF; purification
by co-precipitation, solvent extraction and
electrodeposition

Soil leached with HCl-HclO4 -HF;
purification by ion exchange, and solvent
extraction and electrodeposition

Ashing; fusion with potassium fluoride (KF)
and potassium pyrosulfate (K2S2O7);
purification by extraction with
triisooctylamine; anion exchange
chromatography and co-precipitation
Ashing; extraction into triisooctylamine,
strip from triisooctylamine with nitric acid
(HNO3), and coprecipitation with
lanthanum.
Analytical Method Sample
Detection
Limit
Fluorometry 5 mg/L
(total uranium)
Neutron No data
Activation
Analysis (NAA)
(235Uand238U)
Delayed neutron 0.4 mg/L
analysis (total
uranium)
Pulsed-laser 0.05 ppb
phosphorimetry
Flow Injection- 0.3 mg/L
Inductively for238U
Coupled Plasma
-Mass
Spectrometry
(FI-ICP-MS)
(isotope
quantification)

Spectrophoto- 1-2 mg/L
metry (total
uranium)

Alpha 0.03
Spectrometry mg/sample
(isotope
quantification)
Alpha No data
Spectrometry
(isotope
quantification)
Alpha No data
Spectrometry



Gross Alpha No data
Spectrometry or
Alpha
Spectrometry
Accuracy
117.5% at
6.3 mg/L
No data



No data


103
(average)
±0.3 ng/L








No data



67%



No data



No data




No data



                                                  26

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Sample Matrix Sample Preparation
Field Survey None
Analytical Method
Scintillation
Detector and
Count Rate
Meter
Sample
Detection
Limit

Accuracy
No data
Air
Air
Air
Air
Air paniculate collection on glass fiber
filter, digestion in nitric acid (HNO3)
Spiked air paniculate dry and wet ashed;
dissolution; coprecipitation with iron
hydroxide and Ca oxalate, purification by
solvent extraction and electrodeposition onto
platinum

Sample collection on cellulose filters;
ashing; extraction with triisooctylamine;
purification by anion exchange
chromatography and co-precipitation

Collection on cellulose filters
Inductively
Coupled Plasma
-Mass
Spectrometry
(ICP-MS) (total
uranium)

Alpha
Spectrometry
Alpha
Spectrometry
Instrumental
Neutron
Activation
Analysis
(INAA)
0.1 mg/L in   No data
final
solution
0.02 dpm/L   No data
for238Uin
solution
0.015 pCi     No data
0.03 mg per   No data
filter
       Source: lexicological Report for Uranium [1], Table 6-2
                                                     27

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      Appendix 3: National Priorities List (NPL) Sites that have or may have DU
      Contamination
        NPL Site
                           EPA
                          Region
                                        Description
Maxey Flats Nuclear       Region
Disposal, Hillsboro,        4
Kentucky (NPL-1986)
Malta Rocket Fuel Area,    Region
Malta, New York (NPL-    2
1987)
Savannah River Site,
Aiken, South Carolina
(NPL-1989)
Region
4
Rocky Flats
Environmental
Technology Site, Golden,
Colorado (NPL-1989)
Oak Ridge Reservation
(DOE), Oak Ridge,
Tennessee (NPL-1989)
Region
Region
4
The Maxey Flats Nuclear Disposal Site is located in eastern Kentucky near
Hillsboro in Fleming County and was a disposal facility for low-level
radioactive waste.  Approximately 533,000 pounds of source material
(consisting of uranium and thorium or ores containing them), 2.5 megacuries
(MCi) of byproduct materials, and 950 pounds of special nuclear material
(i.e., plutonium and enriched uranium) were buried in an area known as the
Restricted Area. Radioactive leachate was discovered to be leaching out of
this area and into surrounding fractured bedrock, soil, and possibly
groundwater. The remediation approach was to capture and evaporate the
leachate, producing solid concentrates that were then buried in onsite
disposal trenches, which were ultimately capped. Other liquid waste was
solidified and buried in another onsite disposal trench, which was also
capped.

This site is located in the towns of Malta and Stillwater, New York,
approximately  1 mile south of Saratoga Lake and 2 miles northeast of
Round Lake. All or part of the Test Station on the site has been leased and
used for a wide range of rocket and weapons testing programs and for space
and other research.  In 1979, approximately 8 grams of uranium
hexafluoride gas were released in a portion of the former GE/Exxon nuclear
building.  The area was cleaned and the contaminated material was sent to
licensed disposal facilities.

Savannah River has produced nuclear materials for national defense since
1951. This site is surrounded by woods and ranges from dry hilltops to
swampland.  The Department of Energy (DOE) reports that a small quantity
of DU was released in January  1984 into Upper Three Runs Creek, which
eventually flows into the Savannah River.  The site remedy has included
groundwater pump and treat, capping/solidification of various disposal
basins and solid waste disposal sites, removal and treatment and/or disposal
of hazardous substances, and shipping process waste to the Waste Isolation
Pilot Project in New Mexico.

This former plant manufactured plutonium components for nuclear weapons
and shut down  operations in 1989 in response to alleged violations of
environmental  statutes.  In 1992, the United States decided not to resume
production at this site. During the summer of 1998, DOE excavated 171
drums of uranium and contaminated soil from Trench T-l. Most of this
waste was shipped to the Nevada Test Site for disposal.

Two facilities at this site produced enriched uranium: the Y-12 plant by an
electromagnetic process, and the K-25 plant by gaseous diffusion. DU is a
byproduct of both of these processes.  There has been leakage from this site
into the surrounding environment. At the Y-12 plant, the Abandoned Nitric
Acid Pipeline was used to  carry waste effluent, which included DU.
Iowa Army Ammunition
Plant, Des Moines
County, Iowa (NPL-
1990)
Region    The Iowa Army Ammunition Plant site's primary activity has been to load,
7         assemble, and pack a variety of conventional ammunition and fusing
          systems. In the fall of 2000, chunks of DU were reported at the Firing Site.
          This has prompted increased focus on the site.
                                                  28

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        NPLSite
                            EPA
                           Region
                              Description
Naval Surface Warfare     Region
Center, Dahlgren,         3
Virginia (NPL-1992)
Materials Technology      Region
Laboratory (U.S. Army),   1
Watertown,
Massachusetts (NPL-
1994)
Gaseous Diffusion Plant   Region
(USEC), Paducah,         4
Kentucky (NPL-1994)
Nuclear Metals,           Region
Concord, Massachusetts   1
(NPL-2001)
NSWC is approximately 4,300 acres and located 40 miles south of
Washington, D. C., along the Potomac River. This site conducts research,
development, testing, and evaluation of surface ship weaponry. Six sites are
related to the former use of munitions, some of which included DU.

Located on 48 acres of land on the north bank of the Charles River, this
arsenal has been in operation since 1816.  In addition to storage, this facility
has expanded into weapons development and production. Specifically, DU
machining, milling, forging, and casting took place on this site.
Radiological contamination present at the site has been remediated and
removed.  At the time of this writing, the site's  remediation focus is on
decontaminating the soil.

This site, which is 3 miles south of the Ohio River and  10 miles west of
Paducah, KY, performed the first step in the uranium-enrichment process.
Separating the uranium by diffusing it through a barrier results in several
end products, one of which is DU. Radiological and volatile organic
compound (VOC) contamination has been found in on- and offsite wells,
and poly chlorinated biphenyl (PCBs) in offsite  surface water bodies.
The Nuclear Metals, Inc., also known as Starmet Corporation, site is located
in Concord, Massachusetts.  In 1958, NMI began operating a manufacturing
facility that produced DU products, primarily as penetrators for armor
piercing ammunition. Soil, sediment, and surface water samples taken
historically and recently indicate that the holding basin, sphagnum bog, and
cooling recharge pond all have elevated levels of DU.	
                                                   29

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    Appendix 4:  Facilities Involved with the Manufacturing or Testing of Products
    Containing DU and/or Components of Products Containing DIT*
       Facility/Site/Company Name                                 Location                 EPA Region
Sierra Army Weapons Depot
Aerojet Ordinance Company
NI Industries
Hughes Helicopter
Armtec Defense Products
China Lake Naval Weapons Center
Elgin Air Force Base Munition Test Facility
Chamberlain
Mason & Hangar
Specific Manufacturing Capability, INEEL
U.S. Army Armament Munitions & Chemical Compound
Olin Corporation
Jefferson Proving Ground, U.S. Army
U.S. Army
Paducah Gaseous Diffusion Plant, U.S. DOE
Nuclear Metal, Inc.
U.S. Army Laboratory Command
Chamberlain
U.S. Army Aberdeen Proving Ground
General Dynamics
U.S. Army Camp Grayling
Honeywell
Honeywell Corporation
U.S. Army Twin Cities Army Ammunition Plant
Kisco
Remington Arms Company Lake City Army Ammunition Plant
Target Research, Inc.
Los Alamos National Laboratory
Los Alamos, New Mexico
Kirkland Air Force Base
Terminal Effects Research and Analysis
Aerojet General Corporation
U.S. Ecology
U.S. Army Ballistics Research Laboratory, Nevada Test Site
Nellis Air Force Base
National Lead Industries
Watervliet Arsenal
Bulova Systems
Lima Army Tank Plant, General Dynamics
Feed Materials Plant, U.S. DOE
Portsmouth Uranium Enrichment Plant, U.S. DOE
Ashtabula Extrusion Plant
Sequoyah Fuel Corporation
General Defense
Carolina Metals
Savannah River Site, DOE
Defense Consolidation Facility
Aerojet Heavy Metals
Martin Marietta Energy Systems K-25 Site*
Day and Zimmerman
Pantex Plant, U.S. DOE
General Dynamics
U.S. Naval Surface Weapons Center
Susanville, California          Region 9
Downy, California            Region 9
Los Angeles, California        Region 9
Los Angeles, California        Region 9
Coachella, California          Region 3
China Lake, California         Region 3
Valpariso, Florida             Region 4
Waterloo, Iowa               Region 7
Middletown, Iowa             Region 7
Idaho Falls, Idaho             Region 10
Rock Island, Illinois           Region 5
East Alton, Illinois            Region 5
Madison, Indiana             Region 5
Fort Riley, Kansas             Region 7
Paducah, Kentucky            Region 4
Concord, Massachusetts        Region 1
Watertown, Massachusetts      Region 1
New Bedford, Massachusetts    Region 1
Aberdeen, Maryland           Region 3
Detroit, Michigan             Region 5
Grayling, Michigan            Region 5
Minnetonka, Minnesota        Region 5
Hopkins, Minnesota           Region 5
New Brighton, Minnesota      Region 5
St. Louis, Missouri            Region 7
Independence, Missouri        Region 7
Dover, New Jersey            Region 2
Los Alamos, New Mexico      Region 6
Albuquerque, New Mexico     Region 6
Albuquerque, New Mexico     Region 6
Socorro, New Mexico          Region 6
Lockwood, Nevada            Region 9
Beatty, Nevada               Region 9
Mercury, Nevada             Region 9
Las Vegas, Nevada            Region 9
Colonie, New York            Region 2
Albany, New York            Region 2
Valley Stream, New York      Region 2
Lima, Ohio                  Region 5
Fernald, Ohio                Region 5
Portsmouth, Ohio             Region 5
Ashtabula, Ohio              Region 5
Gore, Oklahoma              Region 6
Red Lion, Pennsylvania        Region 3
Barnwell, South Carolina       Region 4
Aiken, South Carolina         Region 4
Snelling, South Carolina       Region 4
Jonesboro, Tennessee          Region 4
Oak Ridge, Tennessee         Region 4
Texarkana, Texas             Region 6
Amarillo, Texas              Region 6
Falls Church, Virginia         Region 3
Dahlgren, Virginia            Region 3
                                                30

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	Facility/Site/Company Name	Location	EPA Region
 Hercules                                                        Radford, Virginia               Region 3
 Ethan Allen Firing Range General Electric                       Burlington, Vermont            Region 1
 Hanford Nuclear Reservation, U.S. DOE                         Hanford, Washington           Region 10
 U.S. Army Yakima Firing Range                                Yakima, Washington            Region 10
 Stresau Labs	Spooner, Wisconsin	Region 5	
 * The Martin Marietta Energy Systems K-25 facility is now known as the East Tennessee Technology Park; it was originally known
 as the Oak Ridge Gaseous Diffusion Plant.

 ** This list includes the locations and names of facilities involved in the manufacturing and/or testing of components that were eventually
 incorporated into a  product containing Depleted Uranium (DU). Inclusion on this list does not imply that DU was undeniably present at
 the facility, but only denotes that the listed facility was part of the manufacturing or testing process of some aspect of a product containing
 DU. In a few cases, the components produced at the listed facility did not contain DU at that point of the process.
                                                        31

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Appendix 5: Case Study - Nuclear Metals, Inc. (NMI) site, Concord, Massachusetts

Background
The Nuclear Metals, Inc. (NMI) site, also known as the  Starmet Corporation site, is located on a 46.4-acre
parcel located at 2229 Main Street in Concord, Mi ddlesex County, Massachusetts. The facili ty includes
five interconnected buildings, a paved parking area, a sphagnum bog, a cooling water recharge pond, and
a holding basin.

In 1958, NMI began operating a manufacturing facility on previously undeveloped land. Nuclear Metals,
Inc. prod uced DU prod  ucts, primarily as penetrat  ors for armor piercing    ammunition. NMI also
manufactured  metal powders for   medical applicati ons, ph otocopiers, and specialty  metal products
Disposal was executed via waste stream discharge  . From 1958 to 1985 , NMI discharged wastes to an
unlined hoi ding basin. Extrusion operations o n depl eted uranium prod uced ro ds with a th  in layer of
copper coating that was rem ovedin a nitric acid pickling operation during which "small quantities" o f
copper and uranium  were dissolved in the nitric    acid. The sp ent nitric acid solution w  as collected ,
neutralized with a lim e slurry, and discharged to the unlined, in- ground holding basin along with other
wastes.  Discharge to the holdi ng bas in ceased in 1985  when NMI began using an acid closed-loop
recycling process.

NMI was ren amed Starmet Corporation in 1 997. In  March 1997,  the company's NRC license to handle
source  material (includin g depleted u  ranium, thorium , and tho  rium oxide) was transferred to the
Massachusetts Department of Public Health, Radiation Control Program. The state collected groundwater
samples and detected volatile organic co  mpounds (VOC s) in NMI' s supply well, previously used for
drinking water. Further analy  tical results indicated that the g   roundwater beneath the propert  y wa s
contaminated with radionuclides (i.e., uranium and thorium), and other materials. In addition, a sphagnum
bog on the property was also been sampled and has shown evidence of radionuclides. Soil, sediment, and
surface water samples taken historically and recently indicated that the holding basin, sphagnum bog, and
the cooling water recharge pond all have exhibited elevated levels of depleted uranium.

Cleanup Approach
In 1998, Starmet conducted a voluntar  y partial cleanup of contaminated soils under the Massachusetts
Department of Enviro  nmental Protection (MADEP)  oversight.  The partia  1 cleanup consisted of
excavation  and transporta tion off-site of approxim  ately 8, 000 cubic y ards of soil contaminated with
depleted uranium and copper. The cleanup halted i n late 1998 when Starmet determined that the cleanup
level set by MADEP could not be m et without excavation of a significantl y greater quantity of material.
The site has since been listed on the National        Priorities List; furthe  r evaluation of remaining
contamination at the site will be addressed under EPA authority.

Response Action
A time-critical removal assessment was conducted to determine if buried drums on site  contain hazardous
material. Two areas containing  buried drums and othe r laboratory equipm ent were located  during the
removal assessment: one in a fen ced-in area adjacent to the hoi ding basin and cooling water pond, and
contains approxim ately 70 drum s; the  other, calle d the "old landfill" cont  ains an unknown num ber of
drums  and laborator y equipm ent. A tim  e-critical  removal actio n was conducte d which included: 1)
installation of fencing around t he "old landfill" area where buried drum s are located;  2) re-grading and
capping of the "old landfil 1" area; and 3) installation of a liner in the holding basin to eli minate fugitive
dust and reduce the leaching of contaminated soils into the groundwater. Sampling and  analysis of soils in
the holding basin was conducted in September 2001  to fill data gaps in previous sampling efforts and to
determine if data from past sampling efforts performed by Starmet were comparable to  EPA data. In June
2002, EPA  assumed the groundwater m onitoring program previously performed by Starmet. During the
                                              32

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June 2002 sam pling event, EPA also sam  pled sedi ment and surface  water o n-site and in the Assabet
River. EPA sampled the groundwater m onitoring wells again in July 2003 before turning site work over
to Potentially Responsible Parties.

Progress and Current Status
Removal of 8,000 cubic y ards of soil from the hoi  ding basin b y Starmet under MADEP  oversight has
reduced the threat of potential exposure at the site. A time-critical removal action has been conducted to
prevent the direct contact threat with the contaminated surface soils located in the "old landfill" area, and
to reduce the infiltration of precipitation into the  holding basin soils. EPA  has installed a fence and
warning signs around the perimeter of contaminated soils in the " old landfill" area, has  capped the "old
landfill" area; and, has installed a liner over the hold   ing basin. I n June 2003,  EPA also negotiated an
agreement with five   potentially responsible  pa  rties including:  U.S. Arm  y, U.S. DOE, Whittaker
Corporation, MONY Life Insurance Co., and Textron, Incorporated, for the pe rformance of a R emedial
Investigation/Feasibility Study (RI/FS), which incl udes the perfor mance of an  Engineering Evaluation
and Cost Analy sis (EE/CA). An EE/CA Approva 1 Mem orandum was signed on September 27,  20  02,
which authorizes the performance of an EE/CA in support of aNon Time-Critical Removal Action for the
holding basin and buried  drum areas. A lien has been  recorded on the Star met property at 2229 Main
Street in Concord.

In May 20 01, Starm et transported  1, 700 drum s c ontaining depleted uranium from its So uth Carolina
facility to the site, to facilitate its planned sale  of that facility. Starmet also has approximately 2000 drums
and other containers of depleted uranium wastes and approximately 100 drums of beryllium wastes stored
at the site. Starm et is  currently in  violation of its MADPH radio active materials license be cause it has
failed to remove the stored drums of depleted uranium materials from the site and is therefore not allowed
to process any radioactive  material at the  facilit  y under their li cense. After Starmet indicated that it
planned to c ease operatic ns or file for bankruptc  y, the Comm onwealth of Massa chusetts obtained a
preliminary injunction in  state court i n January 20 02, requirin g Starm et to  continue to provide site
security and necessary  utilities. On  March 15, 2002, th  e state court placed Star   met i nto tern porary
receivership. On or about March 18, 2002, Starmet  abandoned the site property. The tern porary  receiver
provided security  and necessary  utilities, with th  e assi stance  of MADPH, until March 25, 2002.
Thereafter, MADPH beg an providing security at  the site. Starmet filed fo  r  Chapter  11 bankruptcy
protection on April 3, 2002, returned to the site,     and continues to operate  and provi de site security  .
MADPH currently has funding available to provide  security and necessary utilities if needed, through the
financial assurance  mechanism provided under Star met's radioactive  materials license. If MADPH's
funding is exhausted and no other  funding source is available, resulting in a bandonment of the facility,
then EPA may be required to address the security and utilities issues.

In April 2004, the state r  cached an ag reement with the Army to rem ove the  more than 3,000 dr urns of
depleted uranium and other materials from within th e facility. The stat e has procured a co ntractor for
performance of the work, and shipments of dru ms  and other material to the E nvirocare waste disposal
facility in Cl ive, Utah, began in Septem  ber 2005.11 is expected that the state  rem  oval work will be
completed in spring 2006. In Se   ptember 2004, E  PA conditionally a pproved the RI/FS Work Pla n
submitted by de maxi mis, inc., the  pr oject coordinator for the  private PRPs. Field work associated with
the rem edial investigatio n began i  n October 200 4. In Octobe r2004, under the supervi  sionofU.S.
Environmental Protection Agency , de maximis, inc., started an investigation of the Su  perfund Site t o
locate all contain inants and prepare a feasibility  study of the  Site cleanup. So far over 1300 sam  pies of
soil, sediment and water have been  collected and analyzed. Since each sample is analyzed for a number of
different contaminants, the data base contains over 300,000 records. Soil contamination has been found at
several locati ons on the site. Conta mination has  also been located in the groundwater. The m      ajor
contaminant is  uranium. Pol ychlorinated  biphenyls (PCBs) and volatile organic co   mpounds are  also
                                               33

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present. A num her of other die micals have been detect ed at low er concentrations. Analysis of data i s
being conducted to determine the extent of, and the risk from, the contamination.

Under a contract with MA DEP, Envirocare Inc. i s removing all identifiable ra dioactive and other waste
material from the Starmet Plant. Th e material  shipped so fart o Clive, Utah, includes 1 ,315 drums of
uranium tetrafluoride, 1,097 drums of a concrete and uranium mixture (conjoint) and 447 drums of other
uranium waste. Approximately 250 drums of uranium tetrafluoride, 200 tons of uranium metal, and other
miscellaneous waste re main to be shipped. The m aterial is rem oved every working day in two or t hree
Landstar Co. tractor trailers. The work was scheduled for completion by March 31, 2006. Removal of the
radioactive material is required prior to starting the EPA investigation of the buildings and soil and water
beneath them. The funding for the contract was provided by the U.S. Army.

In December 2004, de maximis, inc., under supervision of the EP A, removed from the ground between
the Holding Basin and Cooling Water Recharge Pond a n umber of drums containing some uranium and
beryllium waste, production tools and production materials, buried in 1967.
In April 2003 Weston Solutions Inc., under a contract
with EPA, rem oved fro m the ground i n the area of
the Old Landfill (sout  h  of Bog)  drums containing
uranium and bery Ilium,  more production tools an  d
materials, th en filled, graded and covered the    area.
Another pha se of the plant cleanup,     which will
include the removal of all contaminated equipment, is
anticipated after Starmet leaves the premises.
Further Information
•   httD://vosemite.eoa.aov/r1/nDl  oad.nsf/f52fa5c31faf
    5c885256adc0050b631/7B6349F1A22FFDF385259
    E5006CA840?OoenDocument
    httD://www.crewconcord.ora/oaaes/whats new.html
                                             34

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 Appendix 6: Case Study - Maxey Flats Nuclear Disposal Site, Hillsboro, Kentucky

Background
The Maxey  Flats Nuclear Disposal S ite is locat  ed in eastern  Kentucky, near Hillsboro, in Flem ing
County. The site was a disposal facility for low-level radioactive wastes. The site is located o n a spur of
Maxey Flats, a ridge 300 feet above the surrounding stream valleys. The area surrounding the site is rural
and agricultural. More than 300 people live within  a five mile radius of the restricted area; the closest
residence is within % mile. More than 120 wells and 25 springs are situated within five miles; however,
nearby residents receive household water from a municipal water system.

From 1963 to 1977, the Commonwealth of Kentucky, under authorities granted by the U.S. Government,
licensed private operators including the Nuclear Engi neering Company (NECO) to dispose of low-level
radioactive wastes fro  m m ilitary ships and facilities,   hospitals, universiti  es, corporations, etc.; an
estimated five million cubic feet of material were  disposed. Most was solid waste; however, other waste
types were disposed and some were highly radioactive. Approximately 533,000 pounds of source material
(consisting o f uranium   and thorium ororescontai ning them ), 2.5 m  egacuries (MCi)  of b yproduct
materials,  and 950 pounds of special nuclear material (plutonium and enriched uranium) were buried in an
area known as the Restricted Area.

Between 1973 and 1986 a large  evaporator facility was operated on site to handle contaminated liquids.
During the operation of the facility , workers capped each disposal trench with a layer of soil after it was
filled, but the earth even  tually co llapsed into the  ditches. Water co llected in the trenches, leachin  g
radionuclides into the surroundi ng environment. A restri cted area of approximately  40 acres is situated
entirely on top of  the flats. The fenced and patrolled restricted ar ea encompasses the disposal trenches,
"hot wells" (sealed concre te pipes containing plutoni um and uranium), waste storage buildings, and an
evaporator facility. Including the acquired buffer zone properties, the site occupies 900 acres.

Operations closed in 19 73 and b y 1985, the U.S. EPA had developed a list o  f potentially  responsible
parties (PRPs) fro m the disposal records toward whom to point financial responsibility. In 1986 Maxe y
Flats was placed on the National Priorities List, becoming, at 300 acres, one of the largest Superfund sites
in the hist ory of t he program, and from  1987 to   1991 extensive studies on rem ediation options were
carried out.

Response Action
To assure proper management and closure, the Commonwealth of Kentucky has maintained the site since
the ti me that co mmercial operations ended. The    Remedial Investigation and Feasibility  Study was
conducted from March, 1  987 until Se ptember, 1991 unde r an adm inistrative Order by  Consent. The
Record of Decision was issued in September, 1991. Meanwhile, between December, 1988 and November,
1989, U.S. EPA Emergency Response solidified 286,000 gallons of tanked leachate because of significant
leakage fro m the m etal le achate (radi oactively contaminated tre nch water) tanks. Subseq uently, from
March, 1991 to Septem ber, 1992, U.S. EPA E mergency Response disposed  of the solidif ied leachate
blocks in an  undergr ound on-site tre nch and i nstalled 30 acres of tern   porary ab ove-ground plastic,
impermeable liner to prevent infiltration of rain into the waste trenches.

After negotiations lasting from June,  1  992 until June  , 1995, two Consent Decrees (one fo  r the 50 de
maximis parties and one for the 306    de  minimis parties) arranged for cost allocation and for the
performance of the Reme dial Design (RD) and Re  medial Actio n. After the required pub  lie co mment
periods, the U.S. District  Court activated the decrees in April 1996; the RD for the first o   f two major
cleanup phases ( 1. Leachate Removal and Disposal; 2. Building Demolition, On-Site Disposal, and Other
Items) began immediately thereafter. Construction  of Phase I and Phase II of the reinforced concrete

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bunkers (for disposal of
completed.
                        solidified rad ioactive leachate and oth er contam inated materials) have been
Approximately 900,000 gallons of leachate and have been rem oved from within the landfill s ince current
dewatering operations began  in September, 1998. However, the  median total daily volumes of water
removed declined from   more than 5, 050 gallons  in 1998 to 1 ess than 600 gallons during the 2000
pumping season. Landfill  dewatering  operations we re discontinued duri ng the early  fall of 2000.
Construction of an interim cap to prevent water infiltration with a perimeter drainage system that includes
the groundw ater interceptor channel   has been  completed. To verify  the dr ainage sy stem does not
negatively i mpact erosio n rates, erosion m  onuments have been installed f  or m onitoring the rate o f
erosion.

The completion of the Initial Remedial Phase was declared in October 2003 by U.S. EPA. Remedial work
completed at the Maxey Flats Waste Disposal Site has been under the guidance of the U.S. EPA, Atlanta,
Georgia, and in accordance with the Consent      Decree signed in 1996.    International Technology
Corporation and Shaw Environmental Group performed the remedial construction.

Progress and Current Status
A five  year review was co mpleted in 2 002; other fi ve year reviews are planned for 2 007 and 2012, the
latter of which, if successf ul, will render the Co mmonwealth of Kentucky  fully responsible for the site.
Corrective steps co mpleted in 20 03  have broug ht m ost problems at the   site under control. The steps
include installation of the geomembrane liner, which directs rainwater into a detention basin to be tested
for radioactivity before it is rele ased into a nearby creek. Contaminated water was pumped out of the
storage trenches, solidified with concrete, and bur ied on site.  Autom atic monitoring equipment samples
surface water at multiple locations around the site ev ery six hours for testing. A 550-acre "buffer zone"
has been added around the perimeter of the site to separate it from the surrounding farms and homes.

                                                   Flats' restricted area,  with the excep tion of two
No contaminated water has been found outside Maxey
springs in th e buffer zone where low levels
have been detected. If    work contin ues on
schedule, a per  manent "cap" consisting of
multiple lay ers of liner a  nd soil, with grass
sown on the surface, is planned to cover the
site sometime around 2 012. The to tal cost of
cleanup and m onitoring is expected to exceed
$60 m illion. In addition t o the depleted uranium co ntamination, Maxey Flats is also noted for tritium,
strontium-90, and radium-226 contamination.
                                             Further Information
                                             •   htto://www. waste.kv.aov/Droarams/sf/Maxev+Flats. htm
                                                httD://www.eDa.aov/Reaion4/waste/nDl/nDlkv/maxfltkv.htm
                                                httD://nucnews.net/nucnews/2006nn/0604nn/060423nn.txt
                                              36

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       Appendix 7:  Treatment Defined by NCR

The concept of treatment is discussed in the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP) under Section 300.5, as follows:
      "Treatment technology" means any unit operation or series of unit operations that alters the
      composition of a hazardous substance, pollutant, or contaminant through chemical, biological, or
      physical means so as to reduce toxicity, mobility, or volume of the contaminated materials being
      treated.  Treatment technologies are an alternative to land disposal of hazardous wastes without
      treatment.

The NCP further states that

      "EPA expects to use treatment to address the principal threats posed by a site, wherever
      practicable. Principal threats for which treatment is most likely to be appropriate include liquids,
      areas contaminated with high concentrations of toxic compounds, and highly mobile materials."
      (See Section 300.430 (a)(iii)(A))

The preamble to the NCP provides further clarification of treatment:

      "This goal [treatment expectation] reflects CERCLA's preference for achieving protection through
      the use of treatment technologies that destroy or reduce the inherent hazards posed by wastes and
      result in remedies that are highly reliable over time. The purpose of treatment in the Superfund
      program is to significantly reduce the toxicity and/or mobility of the  contaminants posing a
      significant threat (i.e., "contaminants  of concern") wherever practicable to reduce the need for long-
      term management of hazardous material. EPA will seek to reduce hazards (i.e., toxicity and/or
      mobility) to levels that ensure that contaminated material remaining on-site can be reliably
      controlled over time through engineering and/or institutional controls.

      Further, the Superfund program also uses as a guideline for effective treatment the range of 90 to 99
      percent reduction in the concentration or mobility of contaminants of concern (see preamble
      discussion below on "reduction of toxicity, mobility or volume" under Section  300.430 (e)(9)).
      Although it is most important that treatment technologies achieve the remediation goals developed
      specifically for each site (which may be greater or less than the treatment guidelines), EPA believes
      that, in general, treatment technologies or treatment trains that cannot achieve this level of
      performance on a consistent basis are not sufficiently effective and generally will not be
      appropriate. [See 55 FR 8701]

For further information on this definition please contact EPA's Office of Superfund Remediation &
      Technology Innovation.
                                               37

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                      U.S. Environmental Protection Agency
                        Office of Radiation and Indoor Air
                           Radiation Protection Division
                         1200 Pennsylvania Avenue, NW
                             Washington, DC 20460
                                EPA 402-R-06-011
                                 December 2006
                             www. epa. gov/rad iation
                                        41

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