United States Office of EPA 520/1 -83-025
Environmental Protection Radiation Programs November 1983
Agency Washington, DC 20460
Radiation
&EPA Prediction Parameters
of Radionuclide Retention
at Low-Level
Radioactive Waste Sites
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Prediction Parameters
of Radionuclide Retention
at Low-Level Radioactive Waste Sites
by
James Neiheisel
November 1983
/U.S. Environmental Protection Agency
Office of Radiation Programs
Washington, D.C. 20460
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FOREWORD
The Low-Level Radioactive Waste Policy Act of 1980 makes each State
responsible for disposing of low-level radioactive waste (LLW) either
within the State or outside the State under compacts with other States.
The States have requested, through the Presidentially-established State
Planning Council on Radioactive Waste Management, that EPA provide a
generally applicable environmental standard for the disposal of LLW. As
a result of this request, EPA proposes to develop an applicable LLW
standard in accordance with the authority and provisions of the Atomic
Energy Act of 1954, as amended.
The EPA Office of Radiation Programs (ORP) plans to complete
specific technical tasks during the development of the LLW standard.
These tasks include waste classification and health risk assessments
using model systems on a number of disposal options.
As part of the ongoing technical tasks, the Los Alamos National
Laboratory, under Interagency Agreements with the Department of Energy,
has assisted in providing laboratory and field data to establish a
predictive methodology for States and State compacts to assess
radionuclide retention at potential LLW sites. The methodology is based
on data from three LLW sites situated in contrasting climates and
surficial deposits. This report presents preliminary results obtained
with the prediction methodology, which is a rapid, inexpensive method
aligned with the capabilities of conventional laboratories. This
predictive method, if fully developed, could replace the acceptable but
more expensive sorption coefficient (Kd) method in the selection of
suitable potential LLW sites.
The Agency invites all readers of this report to send any comments
or suggestions to Mr. David E. Janes, Director, Analysis and Support
Division, Office of Radiation Programs (ANR-461), U.S. Environmental
Protection Agency, Washington, D.C. 20460.
Glen L. Sjoblom, Director
Office of Radiation Programs
iii
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ACKNOWLEDGMENTS
The author wishes to thank Dr. Lewis Battist and Mr. G. Lewis Meyer
of the Office of Radiation Programs, U.S. Environmental Protection Agency,
for critical review of this report and for the many helpful suggestions
and discussions during the course of this work.
The laboratory tests by the Los Alamos National Laboratory for
mineralogy and special considerations on site specific samples from the
low—level radioactive waste sites are acknowledged with thanks.
Appreciation is especially extended to Dr. Kurt Wolfsberg for his
technical assistance relating to cause of variation in the sorption
ratios (Kd's) of some of the radionuclides at the low-level radioactive
waste sites.
The assistance of Mr. Miles Kahn and Ms. Mary Anne Culliton for
editorial review and Ms. Sharon Scott of this office for typing is
gratefully acknowledged and appreciated. Appreciation is also extended
to Ms. Barbara Doyle for the drafting of charts and figures.
iv
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CONTENTS
Page
Foreword ill
Abstract iz
Introduction .. 1
Surficial Deposits of the Contiguous United States 2
Low Level Waste Sites 2
Clay Mineral Suite of Surficial Deposits 4
Chemical Aspects of the Surficial Deposits 6
Background Terrestrial Radiation Levels 6
Factors Governing Radionuclide Retention 7
Texture 7
Sorptive Minerals 7
Chemical Factors 11
Method of Investigation for Predictive Parameters 13
Sorption Coefficient (Kd) Measurements 13
Fractionation of Samples 14
Quantitative Mineral Analysis 15
Chemical Factors 17
Comparison of Radionuclide Retention in Surficial Deposits 17
Texture and Mineral Composition in Relation to Kd Values 19
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CONTENTS (continued)
Page
Sorption Coefficient Versus Percent Sorptive Minerals 23
Other Control Factors 23
Summary and Conclusions 25
Recommendations 26
References 28
TABLES
1. Typical Kd Values of Sr and Cs on Pure Mineral Phases
Characteristic of Sand, Silt, and Clay-Size Materials 8
2. General Relationship between Texture, Surface Area,
and Clay Mineral Composition 10
3. Texture and Mineral Composition of Beatty and Barnwell
Low-Level Radioactive Waste Sites 21
4. Radionuclide Sorption (Kd's) of Samples at Beatty and
Barnwell Sites in Ambient and Controlled Atmospheres 22
FIGURES
1. Surficial Deposits of the Contiguous United States
and Location of Three Commercial Low-Level Radioactive
Waste Sites 3
2. Comparison of Clay-Mineral Suite of Major Surficial
Deposits of the Contiguous United States and
World Ocean Basins . 5
vi
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FIGURES (continued)
Page
3. Chemical Structure and Comparative Particle Size of
Common Clay Minerals in the Surficial Deposits 9
4. Method for Determining Percent Sorptive Minerals
in Samples from LLW Sites 16
5. Average Radionuclide Retention at Three Low-Level
Radioactive Waste Sites Located in Three Major
Surficial Deposits of the Contiguous United States 18
6. Ternary Textural Diagram of Sand-, Silt-, and Clay-Size
Materials at Three Low-Level Radioactive Waste Sites 20
7. Percent Sorptive Minerals Versus Sorption Coefficient
(Kd) of Cesium and Strontium for Samples from the
Barnwell and Beatty Low-Level Radioactive Waste Sites 24
vii
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ABSTRACT
The Environmental Protection Agency is evaluating site-specific
toils from the Beatty, Nevada; Barnwell, South Carolina; and West Valley,
Few York, low-level radioactive waste (LLW) sites to determine critical
>arameters for predicting radionuclide retention. Each of the sites is
.ocated in one of the three major surficial deposits of the contiguous
Inited States. These deposits have a unique assemblage of sorptive
linerals, texture, and environmental factors that affect the sorption
lechanism of the radionuclides. The sorption coefficients (Kd) of most
•adionuclides are highest in the alkaline Alluvial Basin deposits which
contain montmorillonite and zeolites as principal sorptive minerals.
A plot of the percent sorptive minerals, determined by an applied
[uantitative technique, versus the sorption coefficient (Kd), reveals
:hat a linear relationship exists for strontium and cesium in some of the
Leposits. Thus, strontium and cesium are predictable in relation to
lineral type and quantity in a given chemical environment. Other
•adionuclides, however, reflect retention governed more by chemical
factors such as pH, Eh (redox potential), presence of organics, ligands,
md nature of the groundwater. Uranium, for example, shows high
•etention at the Barnwell site but low retention at the other two sites
rLth the carbonate ligand in the groundwater probably being the main
:ontrol factor.
ix
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INTRODUCTION
The Low-Level Radioactive Waste Policy Act of 1980 requires that
by 1986 the States dispose of their low-level radioactive waste within
their State or outside the State under compact with other States. The
Environmental Protection Agency (EPA) is developing numerical, generally
applicable environmental standards under the authority of the Atomic
Energy Act of 1954, as amended. During the standards development, EPA
plans to complete specific technical tasks to use in assessing health
risks of selected disposal options. As part of the technical tasks, in
concert with health risk assessments, natural and engineered barriers are
being evaluated at three existing low-level waste sites that have
geologic media typical of the three major surficial deposits of the
contiguous United States. This paper addresses the radionuclide
retention capabilities of the natural barrier and presents a methodology
for assessing potential radionuclide retention at future low-level
radioactive waste (LLW) sites.
Soil has the ability to slow down the movement of radionuclides.
Because of the many variables involved, this aspect has not been
considered as an important factor in selecting waste sites. At present,
laboratory measurements of site specific soils for sorption coefficients
(Kd's) of radionuclides is the most acceptable method of characterizing
radionuclide retention, but this method is also very expensive and time
consuming. In this method of analysis, the Kd of each radionuciide of
concern is measured for its specific activity in the solid and liquid
phase in controlled batch or column tests. The number generated)as the
ratio of the radionuclide retained on the solid divided by that in the
liquid is the Kd of the radionuclide. The higher the Kd number, the
greater the retention of the radionuclide. The Kd numbers vary in
relation to several variables of which pH and type and amount of sorptive
minerals are important; these factors can be measured with confidence by
prescribed methods. Other factors are also important in control of
radionuclide retention, and many of these are similar within similar
surficial deposits.
The basic methodology prescribed in this report is to examine the
Barnwell, South Carolina; Beatty, Nevada; and West Valley, New York,
sites, each as a unique site within differing major surficial deposits.
The textural, mineralogical, and chemical factors of each of the LLW
sites within each of these surficial deposits is compared with the Kd
measurements of radionuclides on site specific soils and groundwater from
each of these sites to identify predictive parameters. The amount of
sorptive minerals at each site is varied in quantity so that proportional
increases of Kd may be related to type and amount of sorptive minerals.
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A quantitative assessment of the mineralogy is required to determine the
precise amounts of sorptive minerals in the respective samples for
comparison with the Kd measurements. Preliminary results show that
prediction of some of the radionuclides may be possible by careful
mineral analysis.
The surficial deposits found at the three LLW sites cover
large areas of the contiguous United States and are not confined to
conventional physiographic boundaries. Since each deposit has a unique
assemblage of minerals and soil and groundwater chemistry, a comparison
of their capabilities to retard the migration of radionuclides also lends
itself to considering the factors which control the sorption mechanisms
of radionuclides.
The prediction method presented is tentative and requires
validation. However, the methodology is less expensive and less
time-consuming than the conventional Kd method for some of the important
radionuclides and could be of value in selecting future LLW sites.
SURFICIAL DEPOSITS OF THE CONTIGUOUS UNITED STATES
The low-level radioactive waste (LLW) sites at Barnwell,
South Carolina; Beatty, Nevada; and West Valley, New York, are located
in unconsolidated surficial deposits which cut across physiographic
provinces and occur in varying thicknesses above bedrock. Hydrologists
have classified surficial deposits into surficial regions with similar
physical properties, spatial locations, climate, and other factors
relating to groundwater. The U.S. Water Resource Council (1968) has
described the major areas of potential groundwater development and has
delineated most of the major surficial deposits. Hunt (1974 and 1977)
has described and mapped the geology of these surficial deposits. The
surficial deposits shown in Figure 1 are those described by the the U.S.
Water Resource Council (1968) with modification to include the New
England glacial deposits by Hunt (1974).
Low Level Waste Sites
The LLW sites considered in this investigation are located in three
different major surficial deposits which are present to some extent in
46 of the contiguous United States. West Valley, New York, is located in
the Glaciated Central Region in transported glacially derived deposits of
Pleistocene age; these constitute the youngest deposits. Barnwell,
South Carolina, is situated in the Atlantic Coastal Plain in the
unconsolidated marine sediments of Tertiary age. Beatty, Nevada, is
located in the unconsolidated Alluvial Basin deposits of Tertiary age in
the semi-arid to arid western States; these continental deposits are
derived from the weathering of adjacent mountain ranges.
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::::: ATLANTIC AND GULF
BEATTY, NV WS3S
Figure 1. Surficial deposits of the contiguous United States and location of three commercial low-level
radioactive waste sites. Source: U.S. Water Resource Council (1968) with modification to
include glacial deposits of New England after Hunt (1974).
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Clay Mineral Suite of Surficial Deposits
The clay mineral suite of the surficial deposits at each of the
sites is related to its source rock, weathering conditions, and history
of deposition. Since the clay minerals constitute the major sorptive
mineral components of these deposits, their distribution in relation to
climate and geologic factors could be expected to be reflected in a
spatial pattern within the major surficial deposits. This study and the
investigations of others indicate that the clay minerals and zeolites are
the most sorptive materials as regards radionuclide retention by the
common minerals. In general, the sorption potential of the common clay
minerals from highest to lowest are montmorillonite, illite, chlorite,
and kaolinite.
Millot (1979) discussed the general climatic control over clay
minerals on a global basis. Montmorillonite (smectite) is most common
from weathering of volcanic rock in poorly drained areas of the middle
latitudes, while kaolinite occurs most abundantly in humid tropic zones
where chemical leaching is heavy (Millot, 1979). Illite and chlorite
appear most abundantly in the colder, higher latitudes. This general
relationship is displayed in Figure 2 in the world ocean sediment
distribution patterns (Neiheisel, 1983). Kaolinite is unique to the
Atlantic Ocean because of the predominance of equatorial drainage from
the intraplate regions of continents into a relatively smaller ocean
basin and the lack of trenches which enables its transport to deposition
sites across the basin. The sediment of the Pacific Ocean, by contrast,
is dominated by a montmorillonite clay-mineral suite in the middle
latitudes and equatorial regions and a chlorite-illite clay-mineral suite
in the high latitudes.
The clay-mineral suites of the surficial deposits of the continents
have a distribution pattern that generally parallels that of the ocean
basins (Figure 2). The illite-chlorite clay-mineral suite is
characteristic of The Glaciated Central Region which is comprised of
materials transported by the continental glaciers of the Pleistocene age
from colder, northern latitudes. The montmorillonite-rich loess
deposited by the prevailing westerly winds constitutes sizeable local
surficial features over considerable portions of the glacial tills of the
Glaciated Central Region; however, the predominant clay-mineral suite of
this region is best characterized as illite-chlorite. The Alluvial Basin
deposits of the western United States are comprised predominantly of
montmorillonite derived from weathering of volcanic rock abundant in the
Cretaceous and Tertiary age deposits of that region. Kaolinite is
characteristic of the Atlantic Coastal Plain, and montmorillonite
constitutes the principal clay mineral of the Gulf Coastal Plain
(Figure 2). The kaolinite of the Atlantic Coastal Plain is derived from
the weathering of the adjacent Appalachian System which has a relatively
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EXPLANATION
PREDOMINANT CLAY MINERALS
KZZ3 MONTMORILLONITE
KAOLINITE
rrrrm ILLITE
Figure 2. Comparison of clay-mineral suite of major surficial deposits
of the contiguous United States and world ocean basins.
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warm climate, granitic source rocks, and acid leaching environment
favorable to the formation of kaolinite. The Gulf Coastal Plain, by
contrast, contains clay minerals transported from the montmorillonite-
rich western States.
Chemical Aspects of the Surficial Deposits
The chemical environmental factors of the surficial deposits
influence radionuclide retention. Onishi, et al. (1981), have listed pH,
Eh, cation exchange capacity (CEC), competitive ions, presence of
oxyhydroxides, and presence of organics and inorganic ligands as
important chemical factors affecting the sorption mechanism of some of
the radionuclides. Of those chemical factors, the pH is perhaps the
least variable and most highly significant.
The pH of the Atlantic Coastal Plain and Glaciated Central Region is
generally acidic and encompasses a pH range of 4 to 7- The Alluvial
Basin deposits, by contrast, are alkaline with the pH range between 7 and
9. The alkaline pH is a result of evaporation of calcium carbonate
deposits formed in the unsaturated zone of semi-arid to arid regions.
Swanson (1982), in an investigation of the stability of nickel and cobalt
in Hartford soil, demonstrated that the retention capability of these
radionuclides is higher in the alkaline pH (9.0) as compared to an acid
pH (6.0). Thus, one might expect greater retention of radionuclides in
the Alluvial Basin deposits based on the pH alone for some of the
radionuclides. However, the most highly sorptive minerals also occur in
these deposits, and radionuclide retention is predictable for some of the
radionuclides that are specifically controlled by the mineralogy.'
Background Terrestrial Radiation Levels
Data on the background terrestrial radiation levels of United States
surficial regions in the vicinity of nuclear power plants have been
compiled by Oakley (1972). This information, extrapolated to the total
surface area of the United States, revealed the lowest terrestrial
background reading in the Atlantic and Gulf Coastal Plain regions (mean
dose equivalent of 22.8 mrem/y). The northern central areas had
intermediate background radiation levels (mean dose equivalent of
45.6 mrem/y), and the highest readings were in the Denver area of the
Rocky Mountain region (mean dose equivalent of 90 mrem/y). The Alluvial
Basin surficial deposits apparently have a background reading of
intermediate range if the Reno, Nevada, area is cited as typical (dose
equivalent of 45.6 mrem/y). More recent airborne radiometric'data from
the DOE National Uranium Resource Evaluation (NURE) program conducted
between 1976 and 1982 could provide total coverage and could update
present values. The background terrestrial radiation values of the
surficial deposits to some degree reflect the mineralogical and chemical
environments of these units and may provide correlative information of
value in defining radionuclide retention.
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FACTORS GOVERNING RADIONUCLIDE RETENTION
Texture
Korte, et al. (1976), have determined that the clay, content (less
than 2 micron size) of a soil was the more useful parameter of several
considered in determining retention or attenuation of a particular
element in several soil types. The parameters considered included cation
exchange capacity, pH, surface area, free iron oxides, total Mn, soil
texture, soil class, and cursory mineral analysis. Gee and Campbell
(1980), in an analysis of two Hanford, Washington, soils in which the
only difference between the soils was the amount of clay-size materials,
found radionuclide retention greatest in the sample with the higher clay
content. Several other investigations leave little doubt that the most
sorptive minerals are in the clay-size fraction. Thus, a first
approximation of radionuclide retention might be made on a standard
texture grain-size accumulation curve that gives weighted amounts of
sand, silt, and clay-size fractions.
Ames and Rai (1979) published summary information of strontium and
cesium retention on pure mineral phases. Quartz and feldspar, more
common to sand and silt-size fractions, have low retention (Kd) values
compared to the common clay minerals of clay-size fractions (Table 1).
Montmorillonite, the common clay mineral with the greatest
radionuclide retention, occurs in the smallest size range of the common
clay minerals; average kaolinite, illite, and montmorillonite sizes are,
respectively, 1.0, 0.3, and 0.1 microns in the direction of the larger
average dimension (Figure 3). Montmorillonite, with smallest particle
size, has the largest surface area per unit volume. The correlation 'of
surface area to clay mineral species is apparent from measurements of
soils at several locations in two separate investigations (Table 2). If
the surface area is divided by the percent clay fraction for the
predominant clay mineral species, it is apparent that the ratio for
kaolinite approximates 1.5, whereas the ratio for the montmorillonite-
rich clay size approximates 5 on several samples reported by Korte,
et al. (1976); this is also apparent in the data presented by Pietrzak,
et al. (1981). Illite has a ratio between that of kaolinite and
montmorillonite which correlates with the particle size data depicted in
Figure 2. Thus, we see that texture and surface area reflect the mineral
composition.
Sorptive Minerals
The term sorption, as used in this investigation, includes
adsorption and absorption of radionuclides on solids from an aqueous
solution. For cesium and strontium, the clay minerals having the highest
sorptive characteristics, in increasing order, are kaolinite, illite, and
montmorillonite (Table 1). This relative order is also generally similar
for other radionuclides for which cation exchange is an important
sorption mechanism. The sorption potential of the clay minerals for a
radionuclide is related to a number of factors, including their charge
and structural and chemical characteristics.
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Table 1. Typical Kd Values of Strontium and Cesium on
Pure Mineral Phases Characteristic
of Sand, Silt, and Clay-Size Materials
Distribution Coefficient (Kd)
Texture Minerals Strontium Cesium
Sand-Size Quartz 0-5 0
Feldspar 9 9
Mica 5 5-15
Silt-Size Quartz 0-5 0
Feldspar 9 9
Mica 5 5-15
Clay-Size Kaolinite 15 45
Illite 100 400
Montmorillonite 150 4900
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\o
^ xxX
oKt
11 1
1 XXX
y xxx
Ji i
m r
1 vs-vz
i
4
c
J
ro+pt
io o_
1 1
XX/K
if )
"XXX
.1
KAOUNITE
ILLITE
MONTMORILLONITE
A - Structural thickness of three common clay minerals in angstom units (A)
0.1 |J
r>
I I
—O..IM —
ILLITE
EXPLANATION
= TETRAHEDRAlLAYER
~) = OCTAHEDRAL LAYER
• OXYGEN OR HYOROXYl
KEV O ALUMINUM. IRON
OR MAGNESIUM
• SILICON
3T
•4- 0001|i
MONTMORILLONITE
KAOLIN ITE
B - Comparative particle size of common clay minerals in micron units in natural deposits
Figure 3. Chemical structure and comparative particle size of common clay minerals in the surficial deposits.
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Table 2. General Relationship Between Texture, Surface Area,
and Clay Mineral Composition
Number of
Soil Samples
2
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The clay mineral structures of kaolinite, illite, and montmorillonlte
are depicted in Figure 3. Kaolinite is made up of one tetrahedral sheet
and one octahedral sheet with the sheets strongly held together by
hydrogen binding. Kaolinite particles have a small negative surface
charge, and sorption is believed to be mainly along broken bonds at the
edges of the crystal structure.
Illite consists of one octahedral sheet between two tetrahedral
sheets (Figure 3). The charge density of illite is the highest of the
three clays considered, but due to its neutralization with
non-exchangeable potassium ions, the cation exchange capacity is
relatively low. Sorption is largely on external surfaces of this clay
mineral.
Montmorillonite clay is the more common variety of the smectite clay
minerals. It has a layer structure similar to illite, but, in addition,
has one-to-two layers of water between tetrahedral sheets, with thickness
depending on the variety of cationic species in the water interlayer
(Figure 3). Sorption occurs on both the surface and in the water
interlayer system. Montmorillonite has an intermediate charge but has
the highest sorption and cation exchange capacity of the clay minerals
because of the unusual intercalation properties and small particle size
(less than 2 microns).
The zeolite clinoptilolite occurs in fair abundance in the Alluvial
Basin deposits. Sorption measurements by Daniels, et al. (1982), on the
clinoptilolite of Yucca Mountain tuffs for cesium indicate a Kd of
3.8 x 1C)4 ml/g; strontium has generally similar sorption ratios for
this zeolite. This mineral ranks with montmorillonite in sorption
potential for many of the radionuclides. The measurement of
clinoptilolite and other zeolites, therefore, is important in evaluating
radionuclide retention potential of minerals.
The presence of quartz, feldspar, and mica, common in the sand and
silt-size fractions of the surficial deposits, is considered to
contribute little to the sorption of the radionuclides. Since sorbent
minerals of clay size occur as coatings on some of the sand- and
silt-size minerals, radionuclide retention is significant in larger size
fractions because of the sorptive clay coatings, as will be shown later.
The values listed in Table 1, for example, are for pure mineral phases
free of adhering sorptive minerals of clay size.
Chemical Factors
Some of the chemical factors that may govern radionuclide retention
include pH, Eh (redox potential), cation exchange capacity, and the
presence of ligands, organics, and oxyhydroxides. The cation exchange
capacity is a useful correlation to clay mineral composition, but
according to Korte, et al., 1976, this parameter does not necessarily
improve the ability to predict the movement of cations through the
11
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natural soils. The cation exchange capacity is expressed in
milliequivalents per 100 grams. Average values for pure mineral phases
are 10 for kaolinite, 15 for illite, and 100 for montmorillonite. While
cation exchange capacity is not as significant for most radionuclides, it
is, however, considered especially significant to strontium, cesium,
Plutonium, and americium (Onishi, et al., 1981).
The pH is probably the most important chemical factor controlling
the sorption of some of the radionuclides. Within the surficial
deposits, this value is generally within a fixed range and given more
test data, predictions based on this parameter are a foreseeable
possibility for some radionuclides. The alkaline nature of the western
soils is related to caliche formation in the semi-arid to arid climate,
while the soils of the humid eastern United States are generally acid in
nature. The marked change in radionuclide retention with change in pH
demonstrated by Swanson (1982) for nickel and cobalt in a Hanford soil
was discussed in an earlier section.
The Eh (redox potential) in the surficial deposits is oxic in
nature. However, reducing conditions may occur in some trenches of LLW
containing high concentrations of organics or oxygen depletion factors
that result in a depleted quantity of oxygen such as reported by Weiss
and Colombo (1980) for the West Valley site. As shown by Onishi, et al.
(1981), the radionuclides most sensitive to such change are technetium,
uranium, neptunium, and plutonium. Technetium, for example, has low
retention under oxic conditions but moderate retention under reducing
conditions.
The chemical factors within the surficial deposits are more
difficult to predict because of a lack of understanding regarding their
physicochemical nature or their predictable occurrence within the
surficial deposits. Taking uranium as an example, Sherwood and Serne
(1983) show that the retention of this nuclide is very sensitive to pH,
oxidation state (Eh), the amount of complexing carbonate or sulfate, and
organic ligands. The presence of high carbonate in the groundwater has
the potential of rapid mobilization of uranium as anionic uranyl
complexes; with relatively low carbonate in the groundwater, the uranium
is less mobile and will be retained in larger quantities by the soil.
Since several sorption mechanisms may operate simultaneously for
some radionuclides, the chemical control factors are difficult to assess
for prediction of radionuclide retention. Their use for predicting
radionuclide retention becomes increasingly greater by comparisons of
chemical differences existing between major surficial deposits of the
contiguous United States. Within the surficial deposits, comparisons of
retention of radionuclides and chemical factors, with fewer variables
involved, may eventually highlight the principal factors for use as
predictive parameters. Laboratory tests may then define the range over
which the particular chemical factor operates.
12
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METHOD OF INVESTIGATION FOR PREDICTIVE PARAMETERS
A method to determine the potential use of textural, mineralogical,
and chemical factors to predict radionuclide retention involves the
following:
(1) Laboratory measurements of sorption coefficients (Kd) of
radionuclides of interest on site-specific samples and with
site-specific groundwater. This constitutes the most
acceptable state-of-the-art measure of radionuclide retention
and will be used as a means of comparison with other
measurements in identifying predictive parameters.
(2) Fractionating samples while retaining chemical integrity to
vary the amount of sorptive minerals in each sample. This is
necessary to identify linear relationships that may exist if
the percent sorptive minerals are compared with the sorption
coefficients of radionuclides.
(3) Quantitative evaluation of sorptive minerals to establish
precise amounts in samples.
(4) Measurement of background radiation and chemical properties of
soil and groundwater believed significant to radionuclide
retention.
Sorption Coefficient (Kd) Measurements
The philosophy, methodology, and applications of sorption
measurements are discussed in detail in the Los Alamos National
Laboratory investigation of the Yucca Mountain tuffs by Daniels, et al.,
(1982). In this investigation using similar methods, site-specific soil
samples from the Beatty and Barnwell sites from 6- and 12-meter depths
were prepared with site-specific groundwater spiked with radionuclides
introduced at the Los Alamos Laboratory. Groundwater with the
experiments were prepared with (1) 59pe, 60co, 85grj 131]^ an(i
l37Cs. (2) 63Ni, (3) 95mTC, (4) natural uranium, (5) 239pu> and
(6) 24lAjn using the appropriate groundwater (Wolfsberg, et al., 1983).
The pH values (+0.5 unit) were ~8.7 and ^6.0 for the Beatty and
Barnwell waters, respectively. The group of mixed nuclides and
were analyzed by gamma counting on a GeLi detector. A Nal detector was
used for 241^. Uranium was determined by neutron activation and
delayed-neutron counting, and 239pu an
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Some measurements of sorption were performed on samples In a
controlled atmosphere of nitrogen containing <0.2 ppm oxygen and
<20 ppm carbon dioxide. The purpose of these measurements was to
investigate possible changes in sorption caused by any reducing minerals
in. the soils. Lower carbonate concentrations (due to loss of CC>2) in
the controlled atmosphere may also affect sorption of some elements. The
pH values of the waters in the controlled atmosphere were 0.5 to 1.0
units higher than in air (Wolfsberg, et al., 1983).
The sorption ratio is defined by
K _ activity on solid phase per unit mass of solid
d activity in solution per unit volume of solution
The Kd is the measure of the specific activity in the soil phase to
that of the specific activity of the liquid phase for the radionuclide of
interest in the controlled batch tests. The higher the Kd number, the
slower a radionuclide will migrate through the soil relative to
groundwater.
Fractionation of Samples
Knowing that minerals with the greatest sorption potential naturally
occur in the finer grain size, the samples were fractionated to study
whether linear relationships exist between proportional amounts of
sorptive minerals and radionuclide retention. The soils reported in this
preliminary investigation were disaggregated and separated texturally by
sieving techniques (Wolfsberg, et al., 1983). The disaggregating
techniques used did not alter the chemical properties. A more vigorous
treatment, such as used in determining particle size distributions, would
have given better textural separations; however, dispersants were avoided
and extremes in aggitation were not used to maintain chemical integrity
of the samples. The fractionated samples are (1) a predominant sand-size
fraction; (2) a silt-size fraction, and (3) a mixed silt- and clay-size
fraction. Some of the clays in these fractions are apparently strongly
mechanically bonded to larger mineral particles. Clays in the Barnwell
samples are largely aggregates of kaolinite clay; Keller (1982) discusses
the unusual nature of this clay mineral which occurs as aggregates in
silt-size as well as typically clay-size materials.
The division of fraction sizes used in this investigation is in
accordance with U.S. Department of Agriculture specifications. In this
grouping, gravel represents particles greater than 2 mm size; sand
represents particles between 2 mm and 50 micron-size; silt represents
particles between 50 micron-size and 2 micron-size; clay represents
particles less than 2 micron-size. Gravel-size particles were removed
prior to testing.
14
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Quantitative Mineral Analysis
The highly sorptive minerals occur mainly in the clay-size fraction,
and some are aggregated in the silt-size fraction. It is therefore
important to use a mineralogical identification method that is as
quantitative as possible to obtain accurate information on weight percent
in the sample. Several quantitative techniques to identify clay minerals
have been described by investigators and have been evaluated by Pierce
and Siegel (1969). While all of the methods have merit, some are more
thorough in addressing all the mineral phases in the sample. The
technique we used is designed to assess, as quantitatively as possible,
the percent of sorptive minerals in the total sample.
The method employs separate x-ray diffraction analysis of
representative portions of both the silt- and clay-size fractions to
eliminate some of the minerals that, if present in a combined silt- and
clay-size fraction, would cause interference peaks on the resulting
diffractogram. Thus, clay minerals are predominant in clay-size
fractions (except for kaolinite at the Barnwell site) and quartz and
feldspar dominate the silt-size fraction. By preparing a standard
grain-size accumulation curve for a sample, the weight of each
size-fraction is determined for use in calculation of the average of each
mineral in the total sample (Figure 4).
The Los Alamos Laboratory performed mineral analysis on the first
samples tested for the Barnwell and Beatty sites using representative and
fractionated samples. Samples were ground to a powder in acetone and
packed into glass holders. Clay samples on filter paper were suspended
in deionized water and sedimented onto glass slides to form oriented
aggregates (Wolfsberg, et al., 1983). X-ray diffraction was performed
using a Siemens D500 Diffractometer providing Cu K-alpha radiation. Each
sample was run from 2o to 32° two-theta. Diffraction data were
collected and processed by the Siemens DIFFRACC V system. The system
identified X-ray diffraction peaks and calculated their d-spacing and
integrated intensities (Wolfsberg, et al., 1983).
Mineral identifications were made by comparison of sample X-ray
diffraction patterns with patterns from the JCPDS mineral file.
Identifications were also confirmed by petrographic examination, where
possible. Estimates of mineral percentages for each of the size-
fractions were made by a combination of methods that included use of
X-ray diffraction intensity peak correction (Hubbard, et al., 1976) and
comparison of sample patterns to patterns for materials of known mineral
composition (Wolfsberg, et al., 1983) .•
The sand-size fraction was analyzed by standard petrographic
techniques using at least a statistical 300-grain count. Samples were
also tested by x-ray diffraction techniques for determining minor amounts
of sorptive clay and alteration or weathering products associated with
the sand-size particles.
15
-------
QUANTITATIVE MINERAL DETERMINATION
CALCULATION
PRODUCT OF FRACTIONAL COMPOSITION
AND GRAIN SIZE
PROCEDURE
• GRAIN-SIZE DETERMINATION
100
10
N- 60
40
20
CLAY-
SIZE
_L
SAND-SIZE
10 50 100
PARTICLE SIZE. MICRONS (
1000
.MINERAL EVALUATION OF SIZE-FRACTIONS
SAND-SIZE - PETROGRAPHIC ANALYSIS
SILT-SIZE - X-RAY DIFFRACTION ANALYSIS
CLAY-SIZE - X-RAY DIFFRACTION ANALYSIS
Figure 4. Method for determining percent sorptive minerals
in samples from LLW sites.
16
-------
The percentage of each mineral in the sample is ideally calculated
as the sum of the fractional percentages of the minerals in the sand,
silt, and clay-size fractions.
Chemical Factors
The chemical factors tested for in this investigation by Los Alamos
Laboratory included the pH, Eh, CEC, natural radioactivity, water
analysis of site-specific groundwater, and soil analysis. The pH and Eh
were determined in the field. Natural radioactivity of the soil was
determined by a GeLi detector and by a liquid scintillation counter for
water (Wolfsberg, et al., 1983). These values and nonradioactive
isotopes or radionuclides of interest were determined and the values
applied as specified by Gillham, et al. (1980), in computing the sorption
coefficient.
COMPARISON OF RADIONUCLIDE RETENTION IN SURFICIAL DEPOSITS
The average sorption coefficients (Kd's) of radionuclides at the
three LLW sites are shown in Figure 5. The Kd values for the Beatty and
Barnwell sites are from laboratory determinations using site-specific
soil and groundwater in tests conducted by the Los Alamos National
Laboratory (Wolfsberg, et al., 1983). Data for the West Valley,
New York, site is from an investigation by Weiss and Colombo (1980) of
Brookhaven National Laboratory in which site-specific soils and trench
water were used. Tests are still in progress at the Los Alamos
Laboratory for the West Valley site.
As anticipated, negligible retention of tritium, carbon-14, iodine,
and technetium occurs at any of the sites since these elements are
present in the case of tritium as water or as anionic species or
covalently bonded compounds. The greatest overall retention of
radionuclides is in the Alluvial Basin deposits which contain an alkaline
pH due to the calcium carbonate (caliche formation) and highly sorptive
montmorillonite and zeolites. Even though the quantity of sorptive
minerals is less at the Beatty site, the types of sorptive minerals
(montmorillonite and zeolites) have higher sorption capabilities than
those of the other surficial deposits. The alkaline pH of the Alluvial
Basin, as compared to the acidic pH of the other deposits, is undoubtedly
also a major contributing factor since solubility of many of the
radionuclides is increased by the more acidic condition.
The highest retention for uranium occurs in the Coastal Plain
sediments at the Barnwell site. Uranium retention is an order-of-
magnitude higher at Barnwell than the jtusr locations, probably due to
the lower carbonate ion content in the groundwater at the Barnwell site
(Wolfsberg, et al., 1983).
17
-------
LLW
SITE
SURFICIAL REGIONS &
CLAY MINERAL SUITE
pH
RADIONUCLIDES - OXIC CONDITIONS
137Cs 239Pu 55Fe
WEST
VALLEY,
NY
BARNWELL,
SC
BEATTY,
NV
GLACIATED CENTRAL
ILLITE
CHLORITE
6.8
ATLANTIC COASTAL
PLAIN
KAOLINITE
5.9
ALLUVIAL BASIN
MONTMORILLONITE
ZEOLITES
7.3
1 | LOW RETENTION, Kd 0 - 100
3l HIGH RETENTION, Kd 1000 - 5000
MODERATE RETENTION, Kd 100 - 1000
VERY HIGH RETENTION, Kd 5000 - 10000
5 • EXCEPTIONALLY HIGH RETENTION, Kd greater than 10000
Rgure 5. Average radionuclide retention at three low-level radioactive
waste sites located in major surficial deposits in the United States.
-------
The retention rates for cobalt and nickel are higher by more than an
order-of-magnitude at the Beatty site in the Alluvial Basin deposits than
at the other two sites. This is probably a function of alkaline pH
rather than a complexing agent. Tewari, et al., 1972, explains the
marked increase of cobalt on Mn02 for the pH between 5.5 and 8.0 as a
result of hydrolysis. Thus, this effect may explain the higher cobalt
retention at the Beatty site compared to that at the West Valley or
Barnwell sites (Figure 5).
Mineralogy can be highly significant in the assessment of the
radionuclide retention of cationic species such as strontium and cesium.
Both strontium and cesium show site specific correlation of sorptive
mineralogy and Kd. The behavior of these nuclides may be predictable if
one uses quantitative mineralogical techniques.
TEXTURE AND MINERAL COMPOSITION IN RELATION TO Kd VALUES
The triangular textural diagram depicted in Figure 6 shows the
quantities of sand-, silt-, and clay-size fractions determined from the
standard grain-size accumulation curve of the samples from the three LLW
sites. The clay-size fraction ranges from 7 to 15 percent at the Beatty
site, and 21 to 36 percent at the Barnwell site. The one sample tested
at the West Valley site contained 33 percent clay-size material.
The texture, mineral composition, and sorption coefficient of
radionuclides on samples from trench depth at the Beatty and Barnwell
sites are listed in Tables 3 and 4. At each site it is generally
apparent that the retention of many of the radionuclides increases with
increased clay-size fraction; however, there are other complicating
factors that govern simple proportional responses with most of the
radionuclides. The texture of site-specific soils, however, does provide
a rough index of relative retention for some of the radionuclides.
An assessment of the highly sorptive minerals in a sample is more
meaningful than the percent clay-size fraction discussed previously if
the quantitative method is used to obtain mineral percentages.
Inspection of the texture versus highly sorptive minerals listed in
Tables 3 and 4 shows general correlation of the clay-size fraction and
the sum of the montmorillonite and zeolite (clinoptilolite) at the Beatty
site. However, this relationship is not apparent for the Barnwell
samples; the amount of sorptive kaolinite exceeds the clay-size fraction
by a considerable amount. The kaolinite in the Barnwell samples occurs
in abundance in all size fractions. While most clay minerals occur in
greatest abundance in the clay-size fraction, kaolinite is more diverse
in occurrence. Keller (1982) describes the wide range in textural
patterns of kaolinite ranging from strictly clay-size to aggregates of
silt-size and even larger sizes as a function of its mode of origin in
varieties of geochemical environments. The kaolinite in the Barnwell
samples calculated from the quantitative mineral evaluation method are
45, 64, and 80 percent in sample numbers 4, 12, and 14, respectively
(Table 3).
19
-------
• BA = BARNWELL, SC
A BT = BEATTY, NV
• WV = WEST VALLEY, NY
BA4
CLAYEY SAND
SAND-SILT-CLAY
Figure 6. Ternary textural diagram of sand - silt - and clay-size
materials at three low-level radioactive waste sites.
20
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Table 3. Texture and Mineral Composition of Soil Samples from Beatty and Barnwell
Low-Level Radioactive Waste Sites
N>
Sample
Number
Beatty
1
2
5
Barnwell
4
12
14
Texture
Sand
89
91
83
58
68
73
Silt
3
2
2
6
11
8
Clay
8
7
15
36
21
19
Mineral Composition
Quartz Feldspar Mica H.M.
15 80
13 80 1 -
8 80 2 -
50 - - 5
35 1
15 5
Kaolinite Montmorillonite Zeolite
3 2
3 3
- 7 3
45
64
80 - -
H.M. = Heavy Mineral.
-------
Table 4. Radlonuclide Sorptlon Ratio (Kd) of Soil Samples from
Beatty and Barnwell Low-Level Radioactive Waste Sites
in Normal and Controlled Atmospheres
Sample
Number
Radionuclides
Beatty
1
2
5
Barnwell 4
12
14
Beatty 1
Barnwell 14
u
Sr
Ni Co Cs
Pu
Fe
Am
Radionuclide Sorption Ratio (Kd) - Oxic Conditions
2
1
3
750
750
550
-
100
82
150
82
142
190
157
115
2,100 2,600 3,300
3,200 620 4,500
3,600 9,000 8,200
115 96 3,500
123 136 3,100
116 24 1,500
Kd - Controlled Atmosphere -
1,700 1,800 4,300
150 130 900
700
5,000
1,800
22,500
3,700
135
1,200
6,000
1,800
6,000
6,000
600
300,000
250,000
100,000
56,000
65,000
130 , 000
Reducing Conditions
16,000
120,000
800
680
140 , 000
120,000
-------
Preliminary evaluation of the West Valley, New York, site samples
reveals a texture and composition relationship in which clay minerals
(illite and chlorite) are contained predominantly in the clay-size
fraction. Thus, for two of the three major surficial deposits, the clay
minerals are predominantly in the clay-size fraction. The exception was
the occurrence of kaolinite at the Barnwell site in both the silt and
clay-size fractions.
SORPTION COEFFICIENT VERSUS PERCENT SORPTIVE MINERALS
Most of the radionuclides at the Barnwell and Beatty sites show a
general increase of sorption coefficient (Kd) with increased sorptive
minerals. A linear relationship was found limited to cesium and
strontium for the Beatty site and for strontium at the Barnwell site
(Figure 7). Daniels, et al. (1982), found a similar relationship for
cesium and strontium in relation to clinoptilolite from the Yucca
Mountain (Nevada) tuff samples. They attribute the proportional Kd
relationship to the presence of clinoptilolite since the Kd of smectite
(montmorillonite) did not follow this relationship. The range of Kd
values found for clinoptilolite in the Yucca Mountain tuff samples are
generally similar for percentages of sorptive minerals in the 10 percent
range such as occurs for the Beatty site samples. Daniels, et al.
(1982), using a nonweighted least squares fit to data points in which
clinoptilolite was approximately 10 percent, found Kd values for
strontium and cesium of 690 + 170 and 430 + 150, respectively. The Kd
values for strontium and cesium at the Beatty site are 80 to 150 and 3000
to 8000, respectively (Figure 7). However, the clinoptilolite
approximates 3 percent and montmorillonite 7 percent of the Beatty
samples. Considering that montmorillonite has a Kd of 4900 for cesium
and 150 for strontium (Ames and Rai, 1979), it would appear that at the
Beatty site the montmorillonite contributes to the sorption ratio.
At the Barnwell site, the plot of percent sorptive kaolinite versus
Kd of strontium provides a straight-line relationship as depicted in
Figure 7- This same relationship is not apparent for cesium at the
Barnwell site as it is at the Beatty site. Some of the data, however, is
still in doubt and additional data are being obtained.
OTHER CONTROL FACTORS
In the more permeable media at the Beatty and Barnwell sites,
oxygenated conditions prevail in the trenches. However, because of the
waste form and impervious nature of the soil of the West Valley site,
reducing conditions occur in some of the trenches (Weiss and Colombo,
1979). The sorptive behavior of radionuclides for site-specific soils at
the Beatty and Barnwell sites was tested by the Los Alamos Laboratory
using a controlled atmosphere of nitrogen (less than 0.2 ppm oxygen and
less than 20 ppm carbon dioxide) to determine if sorptive behavior of
some of the radionuclides may be different from that occurring under
normal atmospheric conditions. The Kd values under the controlled
23
-------
S3
8000
7000
6000
s 5000
a
25
o 4000
I
•a
* 3000
2000
1000
Beatty 2
Beatty 1
I
J_
Beatty 5i
I
I
24 6 8 10 12
PERCENT SORPTIVE MINERALS
14
200
150
F 100
I
1
50
Beatty 5
(Montmorillonite)
I
I
I
Barn well 14
Barnwell 4
I
I
I
10 20 30 40 50 60 70
PERCENT SORPTIVE MINERALS
J I
80
90
Figure 7. Percent sorptive minerals versus sorption coefficient (Kd) of cesium and strontium
for samples from the Barnwell and Beatty low-level radioactive waste sites.
-------
reducing atmospheric conditions are listed in Table 4. The sorption of
plutonium under reducing conditions is higher by a factor of 3 for the
Beatty sample and by a factor of 6 for the Barnwell sample (Wolfsberg,
et al., 1983). Uranium was not tested in the controlled atmosphere.
Similar Kd values were obtained for strontium, cesium, iron, nickel,
cobalt, and americium in both ambient and controlled atmospheres.
The differences in the Kd values of nickel and cobalt at the LLW
sites are believed to be mainly from chemical control factors. The
Beatty site Kd values are an order-of-magnitude higher than those at the
Barnwell or West Valley sites. Swanson (1982) showed that by changing
the pH of an alkaline Hanford solid to an acidic condition (pH-6.0) with
other factors similar, the Kd of nickel and cobalt would be reduced
tenfold. Jenne (1968) presents evidence that the principal sorption
mechanism of cobalt and nickel in the marine sediments is the
coprecipitation of these radionuclides with hydrous oxides of manganese
and iron under controlling conditions of pH and Eh (redox potential).
Similar chemical factors probably control the high retention that might
be expected for cobalt and nickel in the Alluvial Basin deposits relative
to the lower retention in the Glaciated Central Region and Coastal Plain
deposits. More work needs to be done to explore the effects of other
factors before prediction parameters are feasible for nickel or cobalt.
The low sorption of uranium by the Beatty samples compared to that
of the Barnwell samples may be related to the relatively high
concentrations of bicarbonate at Beatty that give rise to poor sorbing
anionic complexes. Similarly, the americium and plutonium colloid
chemistries may be affected by the groundwater composition (Wolfsberg,
et al., 1983).
SUMMARY AND CONCLUSIONS
Each of the low-level radioactive waste sites investigated for
predictive parameters to assess radionuclide retention is situated in
contrasting surficial deposits of the contiguous United States. Each of
these surficial deposits has a unique assemblage of minerals, texture,
and chemical environmental factors that are products of the climate and
geologic history of the deposits. A comparison of the sorption
coefficients (Kd's) for radionuclides at the three sites reveals repeated
similarities within each deposit but large variations in the Kd values
between the contrasting surficial deposits. The Alluvial Basin deposit
has higher retention of radionuclides than either the Glaciated Central
Region deposit or the Coastal Plain deposits.
The most obvious differences in the surficial deposits are (1) the
type and amount of sorptive minerals and (2) the acidic or alkaline pH.
The sorptive minerals are also the finest textured components of the
surficial deposits. Quartz and other minerals common to the sand- and
silt-size particles generally have low sorptive properties.
25
-------
An assessment of sorptive minerals using established methods
to focus on their quantitative proportions in representative and
fractionated samples provides a critical parameter for comparing measured
sorption coefficient (Kd) values of radionuclides. While retention of
most radionuclides increases with increased amounts of sorptive minerals,
a linear relationship between Kd and sorptive minerals is evident for
only cesium and strontium. Linear relationships of percent sorptive
minerals versus sorption coefficient (Kd) values are apparent in the
preliminary evaluations of the Alluvial Basin deposits for both cesium
and strontium and in the Coastal Plain deposits for strontium. The Kd
determination of the Glaciated Central Region deposits is not yet
completed; however, it becomes apparent from this preliminary
investigation that cesium and strontium may be predictable by careful
evaluation of the sorptive minerals in the potential low-level
radioactive waste sites of each region.
The alkaline nature of the Alluvial Basin deposits appears to
account for an order-of-magnitude higher retention of cobalt and nickel
in these deposits than in the acidic surficial deposits. Other chemical
factors, such as presence or absence of iron, manganese, and organics,
and coprecipitation with a hydrous oxide, may also relate to the
retention of. cobalt and nickel.
The groundwater chemistry may be significant in controlling
retention of uranium, americium, and plutonium in the surficial
deposits. Higher uranium retention in the Barnwell deposits may be
related to low bicarbonate concentrati6n as contrasted to the low uranium
retention in the other two deposits containing greater amounts of this
ligand.
The sorption coefficients (Kd's) of tritium, carbon-14, technetium,
and iodine are predictable in that there is negligible retention of these
radionuclides in any of the surficial deposits due to their occurrence as
tritium in water or a covalently bonded compound such as C-14 or as
anions.
RECOMMENDATIONS
Linear relationships that may exist as predictive parameters of the
major surficial deposits can be determined by testing site-specific soils
for the sorptive coefficient (Kd) of radionuclides and the percent and
variety of sorptive minerals by using a quantitative mineral evaluation
method. Variations of amounts of sorptive minerals by fractionation
techniques must maintain the chemical integrity of all samples.
Verification for regional consistency should be conducted on a number of
samples within similar surficial deposits to validate the methodology
apparent in this investigation.
26
-------
Chemical factors which are important as control mechanisms are not
as easily identified as predictive parameters for radionuclide
retention. Comparison of the radionuclide retention between major
surficial deposits, however, are suggestive of potential control
factors. More investigations identifying limits and ranges of chemical
factors for several groundwaters with variation in radionuclide
concentrations are required to provide information applicable to
prediction of radionuclide retention with chemical parameters at this
time.
It is recommended that efforts continue to provide data on
radionuclide retention capabilities for the value it will afford
assessment of future low-level radioactive waste sites. Preliminary
predictive data realized in use of texture and quantitative mineralogical
techniques may eventually also encompass chemical parameters. The
benefits realized will be reflected in health benefits to the nation as
well as advancing our understanding of physicochemical factors relating
to protection of our groundwater from pollution.
27
-------
REFERENCES
Ames, L.L., and Rai, D., 1979, Radionuclide interactions with soil and
rock media, EPA 520/6-78-007, v. 1, p. 253.
Brown, K.S., and Anderson D., 1980, Effect of organic chemicals on clay
liner permeability, in Proceedings of Sixth Annual Research Symposium on
Disposal of Hazardous Waste, David Schultz, editor, EPA-600-9-80-010,
pp. 123-134.
Cahill, J.M., 1982, Hydrology of the low-level radioactive-solid-waste
burial site and vicinity near Barnwell, South Carolina, U.S. Geological '
Survey Open File Report 82-863, p. 31.
Daniels, W.R., Wolfsberg, K., Rundberg, R.S., Ogard, A.E., Kerrisk, J.F.,
et al., 1982, Summary report on the geochemistry of Yucca Mountain and
environs, Los Alamos National Laboratory Report IA-9328-MS, p. 364.
Gee, G.W., and Campbell, A.C., 1980, Monitoring and physical
characterization of unsaturated zone transport—Laboratory analysis,
Battelle Pacific Northwest Laboratory Report PHL-1304.
Gillham, R.W., Cherry, J.A., and Lindsay, L.E., 1980, Cesium distribution
coefficients in unconsolidated geological materials, Health Physics,
v. 39, pp. 637-649.
Heilman, M.D., Carter, D.L., and Gonzales, C.L., 1965, The ethylene
glycol monoethyl ether (EGME) technique for determining soil surface
area, Soil Science, v. 100, pp. 409-413.
Hubbard, C.R., Evans, E.H., and Smith, D.K., 1976, The reference
intensity ratio, I/Ic for computer simulated powder patterns, Journal of
Applied Crystallography, v. 9, p. 169.
Hunt, C.B, 1974, Natural regions of the United States, W.H. Freeman and
Company.
Hunt, C.B., 1977, Surficial geology of the United States, U.S. Geological
Survey Open File Map No. 77-232.
Jenne, E.A., 1968, Controls of Mn, Fe, Co, Ni, Cu, and Zn concentrations
in soils and water: The significant role of hydrous Mn and Fe oxides,
pp. 337-387, In: Trace Inorganics in Water, R.A. Baker, Editor, American
Chemical Society, Advances in Chemistry Series 73, p. 387.
Keller, W.D., 1982, Kaolin, a most diverse rock in genesis, texture,
physical properties, and uses, Geol. Soc. of Amer. Bull, v. 93, pp. 27-36.
Korte, N.E., Skopp, J. , Fuller, W.H., Niebla, E.E., and Alesii, B.A.,
1976, Trace element movement in soils: Influence of soil physical and
chemical properties, Soil Science, v. 122, pp. 35-359.
Millot, G., 1979, Clay, Scientific American, v. 240, n. 4, pp. 108-119.
28
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Neiheisel, J., 1983, Quantitative mineral assessment and radionuclide
retention potential of Atlantic 3800-meter nuclear waste dumpsite
sediments, U.S. Environmental Protection Agency, Technical Paper,
EPA 520-1-83-003, p. 43.
Nichols, W.D., 1980, Hydrologic studies of the unsaturated zone, Beatty,
Nevada, U.S. Geological Survey Professional Paper 1175.
Oakley, D.T., 1972, Natural radiation exposure in the United States,
U.S. Environmental Protection Agency Reports, ORP/SID72-1, p. 62.
Onishi, Y., Serne, R.J., Arnold, E.M., Cowan, C.E., and Thompson, F.L.,
1981, Critical review: Radionuclide transport, sediment transport, and
water quality mathematical modeling, and radionuclide adsorption/
desorption mechanisms, Battelle Pacific Northwest Laboratory, PNL-2901,
p. 339.
Pierce, J.W., and Siegel, 1969, Quantification in clay mineral studies of
sediments in sedimentary rocks, Jour. Sed. Petrology, v. 39, pp. 187-193.
Pietrzak, R.F., Czyscinski, K.S., and Weiss, A.J., 1981, Sorption
measurements performed under site-specific conditions—Maxey Flats,
Kentucky, and West Valley, New York, disposal sites: Nuclear and
Chemical Waste Management, v. 2, pp. 279-285.
Purdic, D.E., 1982, Hydrologic conductivity of a fine grained till,
Cattaraugus County; N.Y., Groundwater, v. 20, n. 2, pp. 194-204.
Sherwood, D.R., and Serne, R.J., 1983, Tailing treatment techniques for
uranium mill waste: a review of existing information, U.S. Nuclear
Regulatory Commission Report, NUREG/CR-2938, p. 56.
Swanson, J.L., 1982, Effect of organic complexants on the mobility of
nickel and cobalt in soils: Status Report, Battelle Pacific Northwest
Laboratory, PNL-4389.
Tewari, P.H., Campbell, A.B., and Lee, W., 1972, Adsorption of Co(2) by
oxides from aqueous solutions, Canada Journ. Chem., v. 5, p. 1642.
Weiss, A.J., and Columbo, P., 1980, Evaluation of isotope migration -
land burial; water chemistry at commercially operated low-level
radioactive waste disposal sites; Progress report through September 30,
1979, Brookhaven National Laboratory Report, BNL-NUREG-51143
(NUREG/CR-1289), March 1980.
Wild, R.E., Oztunali, O.I., Clancy, J.J., Pitt, C.J., and Picazo, E.D.,
1981, Data base for radioactive waste management, Vol. 2, U.S. Nuclear
Regulatory Commission, NUREG/CR-1759.
Wolfsberg, K., et al., 1983, Research and development related to sorption
of radionuclides on soils, Los Alamos National Laboratory Report,
LA-UR-83-800, p. 48.
29
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA 520/1-83-025
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Prediction Parameters of Radionuclide
Retention at Low-Level Radioactive
Waste Sites
5. REPORT DATE
November 1983
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
James Neiheisel
8. PERFORMING ORGANIZATION REPORT NO.
EPA 520/1-83-025
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Office of Radiation Programs
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
TAG Number AD-89-F-1-669-0
and AD-89-F-2-669-0
12. SPONSORING AGENCY NAME AND ADDRESS
Office of Radiation Programs
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Progress Report
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Three low-level radioactive waste (LLW) sites situated within three of the
major surficial deposits of the United States are .being investigated to determine
predictive parameters that may exist for assessing the radionuclide retention at
future LLW sites. Each of the major surficial deposits has a unique assemblage
of sorptive minerals, texture, and chemical environmental factors that affect the
sorption mechanism of the radionuclides. The LLW sites are located at Beatty, Nevada;
West Valley, New York; and Barnwell, South Carolina.
Preliminary results reveal predictive linear relationships for cesium and
strontium in a plot of the percent sorptive minerals versus the sorption
coefficient (Kd). The percent sorptive minerals are determined by a quantitative
mineral method.
Radionuclide sorption control mechanisms of cobalt, nickel, plutonium,
uranium, americium, technetium, and iron reflect some retention related to
mineralogy, but principal retention factors are more related to the nature and
amount of organics, ligands, oxyhydroxides, redox potential, pH, and groundwater
chemistry.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Surficial Deposits
Sorption Coefficient of Radionuclides
Sorptive Minerals
Clay Minerals
Low-Level Radioactive Waste Sites
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
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