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125 L4 L
MICROCOPY RESOLUTION TEST CHART
NATIONAL BUREAU OF STANOAROS -1963
ORNI P-1811

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in the open luonatur at least months
prior to the towanca date of this Micro-
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donce that I has been published, the pa.
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CONF-6 0601-00
DEVELOPMENT AND APPLICATIONS OF MINERALS IN RADIOACTIVE WASTE DISPOSAL A
Tsune, Tamura
CODI FRKCES
RILEASED FOR ANNOUNCEMENT
DEC 21 1065
Hei. Itin Physics Invision
2o $.00; VN 50 Oak Ridge National Libouti
Oak Ridge, Tennesstr: L O
MUCLEAR SCIENCE ABSTRACTS
Clays and related earthen materials have been usefui in providing
solutions to the problem of radioactive waste disposal. As sorhents se-
lective for
lays have been useu i
recontamir. ing waste
solutions. As additives to cement-based slurries used
sc: al by
hydraulic fracturing, they have functioned as liquid and .......ali :
absorbers, as well as cheap substitutes for Portland cement.
In the ::.
velopment of these applications, Information has been ged ned vi. the nature
of the reactions of radionuclides with cia vs waer. which to assess tie
safety ut ground disposal operations generally.
In turn, the use of
radioisotopic techniques has provided valuable information on the nature
of clays and related materials.
The reader is referred to several recently published books for infor-
mation on the over-all probiems of sources, treatments, and discharges
"Research sponsored in the U. S. Atomic Energy Commission under coin
tract with the Union Carbide Corporation.

NOT ARADON
.
AL
of radioactive wastes into the environment (Amphlett, 1961; Mawson, 1965;
Straub, 1964). These reference works describe how synthetic resins and
-norganic exchangers have been used in the decontamination of f1881on
product wastes. This paper considers how several clay minerals and allied
materials are used similarly, particularly in radioactive waste disposal.
The rationale behind the development of these applications and the impii.
cations of the experimental results in understanding reactions of radiocesium
and radiostrontium in ground disposal operations are also discussed. Radio-
cesim-clay mineral reactions are treated in greater detail since the
wechanism of sorption postulated for this reaction originated here and is
structure 18 the dominant factor in radiocesium sorption from radioactive
waste solutions.
Information on the sesquioxides, common constituents in
soil aná clay mineral systems, 18 also included because they complicate
*
the absorption behavior of radionuclides in soils.
3
an
MATERIALS AND METHODS
A
T
.
2
Natural hydrobiotite, which is an interstratified mica-vermiculite
consisting of approximately 50% of each component, was obtained from the
.
To
3
*
.
Zonolite Company mine in Traveler's Rest, South Carolina. Montmorilloni to
(Clay Spur, Wyaning), kaolinite (Macon, Georgia), and 1111to (Fithian,
Illinois), which are the reference clay miuerals in the American Petroleum
Institute's Clay Mineral Standard Project No. 49, were obtained from Ward's
Mineral Establishment. Another 11lite sample was obtained through the
Oklahoma State Geological Survey from Beaver's Bend, Oklahoma. Grundi te,
a commercially available 11lite, was bought from the Illinois Clay Product
Company, Joliet, Illinois.
Reagent grade aluminum oxide and aluminum hydroxide powders served
as reference materials for corundum and gibbsite; these identifications
were established by X-ray diffraction analysis.
The sesquioxide hydrates
of goethite, limonite, and diaspore were purchased from Ward's Mineral
Establishment. Baudte ore was supplied by the Reynolds Metal Company.
A zeolitic mineral, clinoptilolite, was obtained from the Hanford Atomic
Laboratory and was used along with Dowex 50-X12 to compare with activated
alumina (F-20 grade) obtained from the Aluminum Company of America. The
attapulgite clay used in these experiments was obtained from the Mineral
and Chemical Philips Corporation of New Jersey.
The method described by Jackson (1958) was used for cation satura-
tion, except in the cases of potassium and casium saturation where lower
salt concentrations and longer contact times were used. Saturation with
these two cations was established using 2x and 157ce on duplicate samples
and counting the solutions and calculating the sorption.
Ion exchange
capacities were determined using the calcium saturation-versene titration
technique. Surface area measurements were made using the BET nitrogen
sorpcion technique.
The slurry tests consisted of adding a known weight of material to
a bottle containing a measured volume of simulated waste solution. The
hour the pH was redetermined and readjusted if necessary. Sorption was
calculated by counting the supernate after centrifugation using +91C8 and
sr and different concentrations of the appropriate stable ion.
In both
the cesium and strontium tests sodium nitrate was present and its concen-
tration was known. All samples were counted in a well-type gamma scintil-
I
lation counter equipped with a NaI crystal.
LEGAL NOTICE
IMI report wompared NH Nooow of Dover wounted work, Matthar the Ondmed
metes, for the Counterton, nor pertou notte a ball
testom
A. Mahu warrant or representation,
w ood or inthet, wo mapeat to the noor-
rhoy, completo , or weten of the formation contained in the reports of the
al my tatarnation, wheretne, method, or prono soloud the report my mu t o
privately owned out of
3. A . Hallition with repot to the desh, or the dangeroudering from the
w at my internation, perpetuus, method, or pronous dood in the reporte
Ao wood in the above, pornon nothing a ball of the Order moltes my u.
mayns or contractor to Contatou, o employ of mail contraste, to one that
make employs or contructor a this Comentanton, or employee of mail contrator prepared
decomana, or provided nown to, ang termitten permint to Me employment or contract
with the Commiartau, ur me empleynt with more contractar.
CESIUM-SELECTIVE SORBENTS
Chemical Development
Several papors have pointed to the high affinity of Illitic min-
crals for tracer levels of cesium (Frederikseen et al., 1958; Schulz
et al., 1960; Tamura and Jacobs, 1960). One of the important parameters
in this sorption reaction 18 the minimum distance separating the alumino-
sliicate sheet; in illite and micas the distance between the layers is
minimum for the family of 2:1 layer lattice silicates (Tamura and Jacobs,
1960; 1961).
Studies of cesium sorption were extended to solutions containing
high concentrations of cesium; in this case, the ion exchange capacity
cesium sorbed (Jacobs and Tamıra, 1960). Explanations of observed different
responses, based on changes in the 001 spacings of the minerals during
sorption, were offered. One objection to the explanation based on changes
in structure was that different minerals were used to study sorption phe-
nomena and that the differences in response may have been due to chemical
properties or other physical properties of these minerals.
The data in
natural hydrobiotite which had been treated. The distribution coerficient
(K) plotted on the ordinate 18 the ratio of the cesium on the sorbent and
in solution; the solution contained 0.1 M NaCl in addition to the cesium
concentrations designated. Our explanation of the response of these dis-
ferent minerals remains the same as that proposed earlier, and more recent
data serve to strengthen this interpretation (Jacobs and Tamura, 1960).
That is, the increasing K, of the natural material with increasing cesium
concentration is due to the formation of favorable sites for cesium. Such
sites are formed when sufficient cesium ions are present to induce collapse
of the vermiculite layers and to reject the magnesium and sodium ions.
This reaction may be likened to the familiar potassium fixation reaction.
The initial decrease in K, of the natural material is due to tha presence
of biotite (Tamura, 1963). The final decrease in K, 18 caused by satura-
tion of the mineral with cesium and sodium.
When the hydrobiotite 18 treated with potassium ions prior to contact
with the cesium solutions, collapse occurs; and favorable sites for cesium
are formed. However, for cesiu to occupy these favorable sites, it must
- .
.za
-
--
-
-
-
-
-
-
-
-
---
-
Fig. 1. Sorption of Cesium by Hydrobiotite.
ORNL-DWG 63-5247R

R POTASSIUM
SATURATED
NATURAL
MATERIAL
w
.
Kg, DISTRIBUTION COEFFICIENT (ml/g)
CESIUM SATURATED
10-2
104 : 100 100 102 . 103
CESIUM CONCENTRATION (mg/liter)
08
replace the potassium ions; and this it does near the edge of the crystal-
lite, increasing the K, of potassium-Baturated hydrobiotite. Because
cesium cannot readily replace the potassium ions Jocated internally and
because of the limited area of the edge of the crystallite, increasing
cesium concentrations will soon saturate the available sites and reduce
the Kg, as noted in Fig. 1. One must remember that, in the case of natural
hydrobiotite, increasing the cesium concentration increases the number of
collapsed layers (collapse being induced by the cesium); the K-hydrobiotite,
on the other hand, is precollapsed with potassiu.
The responses of cesium and potassium saturated hydrobiotites illus-
trate the differences in materials saturated with two alkali ions. Ob-
viously, the difference in response is due to the differences in exchange-
able cations - potassium and cesium. However, cesium saturation of a
mineral is not essential to produce responses similar to the Cs-hydrobiotite,
What 18 essential 18 that lattice changes which affect the selectivity
factor do not occur during sorption. This requirement is met by such
minerals as kaolinite and montmorillonite which show responses similar to
Cs-hydrobiotite. From these studies it is apparent that, in solutions
containing microconcentrations of cesium, illitic minerals and K-hydrobio.
tite are effective sorbents. At higher concentrations, natural vermiculite
and montmorillonite, which have higher exchange capacities, would be
preferred.
When montmorillonites saturated with different cations were first
heated to 600 to 700°C and cooled, improved sorption of cesium was observed,
and the heat-treated materials showed cesium sorption curves similar to
the K-hydrobiotite (Tamura and Jacobs, 1961).
The explanation offered
was that the heating collapsed the expanded 001 layers to dimensions simi-
lar to the 11lites and micas. An alternate explanation suggested the
possible formation of new compounds of cesium from decomposition of the
clay. The data in Fig. 2 show the influence of heating Na-montmorillonite
and may be used to negate the alternate explanation.
The constant K, re-
sponse for cesium by the unheated and 500°C-heated materials 18 reminiscent
of the response with Cs-hydrobiotite; the constancy of K, over a wide range
of cesium concentrations 18 due to the high ion exchange capacity of the
Na-montmorillonite (76 meq/100 g) as compared with Co-hydrobiotite (11
meq/100 g).
10
Fig. 2. Cesium Sorption by Na-montmorillonite after Heating to
Designate i Temperatures.
ORNL-DWG 63-5187R

- 700°C
600°C4
Kg , DISTRIBUTION COEFFICIENT (ml/g)
500°c
25°C
Cant.
1002
40*9 100 10 102
CESIUM CONCENTRATION (mg/liter)
103
.
3
That heating to 600°C increased the sorption at all cesium concen-
trations suggests the original material was not destroyed. The shape of
the response curves for the 600°C and 700°C samples, when sorption was
measured after one-hour contact (nonequilibrium), also suggests that the
response of both samples was similar, the response of the 700°C sample at
high cesium concentrations being due to a mere extension of the heat treat-
ment; that is, irreversible collapse of the layers rather than the forma-
tion of new compounds resulting from decomposition products. The Ka ranged
from 4100 and 1400 at the 10-7 mg level to 60 and 3 at the 103 mg level
for the 600°c and 700°C samples, respectively.
Applications
Information on the mechanism of radiocesium sorption by clay minerals
is useful in explaining the retention of this nuclide in soils. In sandy
soils, where the clay minerals are scarce, it is possible to adsorb radio-
cesium since the micas are common sand-size particles.
In soils of moderate
and high clay content, 111ite is a common mineral and adsorption would be
expected to be high. Hence, in almost all soil types, effective retention
of radiocesium 18 expected and observed (Tamura, 1964).
At the Oak Ridge National Laboratory (ORNL), Grundite (1111te) is
routinely mixed with low-level waste for radiocesium removal in a waste-
water treatment plant whose capacity is 1.4 x 10° liters/day (Cowser and
Tamura, 1963). Plant efficiency for removal of radionuclides is typified
by the first two years of operation as shown in Table 1. Removals of
strontium and total rare earths (TRE) have averaged 84% and 86%, respec-
tively, using lime and soda ash. Adaition of 200 mg/liter of Grundite
began October 1958 and resulted in increasing cesium removal from 21% to
ALER
86%. The clay feed was also instrumental in increasing the removal of
106 Ru to 76%, of 6°co to 78%, and of gross-beta activity to 88%.
EN
TI
Several advanced waste treatment schemes have also been developed
through pilot plant stage for low-level waste treatment at Oak Ridge,
In
the scavenging ion exchange technique, the cesium and other radionuclides
are sorbed on organic resin exchangers. After the resin 18 spent, the
radionuclides are eluted and Grundite is added to the eluate to sorb the
radionuclides. As with the waste water treatment plant findings, Grundite
showed a significant selectivity for cesium, cobalt, and ruthenium (Parker
and Blanco, 1964). The use of Grundite in this method also suggests
Table 1. Average Percentage Removal of Radionuclides in Plant Tests
90+893r
TREE
1378
106Ru
Goco
Gross Beta
Activity
86
Mar. 1958-Aug. 1959
Sept. 1957-Sept. 1958
Oct. 1958-Aug. 1959
84
--
21
66
49
76
65
78
B. 1959
--
Atotal rare earths.
14
eliminating evaporation of the eluate. In the scavenging foam-separation
technique, the waste 18 treated with a detergent, such as dodecylbenzene
sulfonate, primarily to remove radiostrontium (Davis et al., 1965). The
detergent 18 aerated, and the resultant foam containing radiostrontium is
removed and separately condensed. Since cesium is not removed by the foam
column nor by the scavenging treatment which preceded the foam treatment,
Grundite 18 added in the scavenging step. By adding approximately 60 mg
+
of Grundite per liter, the decontamination of cesium is increased fifteen
fold. The Grundite which is added in this latter application is heated
to 600°C for 20 minutes and cooled prior to use.
This recommendation was
made by us after heating of montmorillonite had shown improved sorption of
radiocesium (Tamura, 1963) and because 1111te from Illinois and the Grundite
were suspected to contain montmorillonite impurities (Jackson et al, 1952;
Yoder and Eugster, 1955).
Heating did not necessarily improve all 11lites; the sample of 11lite
from Oklahoma showed evidence of vermiculite impurities, and heating was
detrimental for radiocesium sorption (Fig. 3).
In this case potassium
2
treatment improved sorption at tracer-level' concentrations. Hence, for
A
CAS
Fig. 3. Removal of Cesium by Illite from Oklahoma.
ORNL-DWG 63-5186K

POTASSIUM SATURATED -
HUNHEATED,
NATURAL
Kg , DISTRIBUTION COEFFICIENT (ml/g)
HEATED TO 500°C
residentini
.
100
***
- 10-2
101 100 101 10²
CESIUM CONCENTRATION (mg/liter)
103
.
..
16
improv.ing natural materials for radiocesium sorption, it is essential that
the mineralogy be known.
In the disposal of intermediate-level waste, the hydrofracturing tech-
nique being developed consists of injecting waste slurries into deep under-
lying rock formations (de Laguna and Houser, 1960). In developing the
mixes, it was found that radiocesium could not be fixed in the matrix even
with high concentrations of Portland cement as shown for injections 3 and
4 (Table 2). By adding approximately 50 g of 11lite per liter of waste,
leachability of radiocesium was greatly reduced, especially evident in the
field grout recovered from injection 5.
Both injections 3 and 4 did noč
contain illite; by introducing 11lite it was possible to increase radio-
cesiu retention, thereby allowing a reduction of cement content and of
cost.
STRONTIUM-SELECTIVE SORBENTS
Chemical Development
Our early work suggested the usefulness of alumina-type compounds
for the selective removal of strontium from waste solutions (Tamura and
Streness
These studies dealt with reagent grade aluminum oxide
Table 2.
Leaching Characteristics of Grouts Blended in the Laboratory
In Field Equipment, and Cored After Field Injection
Injection
Number
Laboratory
Mix
Field
Grout
Cored
Grout
Clay
Addition
12.2
12.0
5.3
Attapulgite
7.0
4.0
Attapulgite
5
2.2
0.3
0.3
Attepuisi te
Attapulgite
Grundite
PM
2
H
***
:
:
E
::
:
EE.
'
..
.
.
.
powder identified as corundum. In soils, hydrous aluminum oxides are
coumon, and it was interesting to evaluate the effectiveness of these
naturally occurring materials.
An aluminum hydroxide (gibbsite) source material, labeled Arkanses
bauxite, was obtained from Reynolds Metal Company. Based on X-ray dif-
fraction and thermal data, there was 60% kaolin and 40% gibbsite in the
sample.
The material was tested and compared with reagent grade aluminum
oxide (I
These tests showed that Arkansas bauxite prior to be.
ing heated was not as effective as aluminum oxide for strontium removal,
but superior to it after being heated to 350°C. Heat treatment was used
to decompose the gibbsite to the oxide in order to obtain a comparable
product.
The weight of heated bauxite was reduced proportionately since
heating resulted in a loss in weight.
To confirm the role of gibbsite in
the bauxite, aluminum hydroxide identified as gibbsite and kaolinite from
Georgia were examined.
The unheated aluminum hydroxide showed very low
selectivity for strontium, but the material heated to 350°C was more se-
lective (Table 3). Kaolinite showed a decrease in selectivity after being
heated to 350°C. These tests not only revealed the usefulness of heated
Table 3. Percentage Removal of Strontium by Several Materials at pH 10
After Different Solid-Waste Solution Contact Times
Waste Solution: 25 ml of 0.1 M NaNO, containing 1 x 10" M Sr<*
Arkansas Bauxdte
Aluminum Hydroxi
Contact
Time
(hr)
Aluminum
Oxdde
(0.2500 g)
Kaolinite
Unheated 350°C
(0.2500 g) (0.2467 g)
Unheated
(0.2500 g)
(0.2500 g)
Unheated
(0.2500 g)
(0.1750 g)
42.4
97.2
17.3
24.2
-
1
4
79.3
86.0
91.6
99.0
2.44
4.40
3.44
46.4
49.6
99.8
99.9
99.9
38.2
•
24
99.5
46.4
24.0
The baudte contained 40% gibbsite and 60% kaolinite.
Aluinum oxius was identified as having the corundum structure; aluminum hydroxide gave gibb,
site x-ray pattern.
20
bauxite but established the importance of alumina- type materials as
strontium sorbers.
Several other hydrous oxide minerals of iron and aluminum were heated
to determine whether they would show properties favorable for the sorption
of strontium. Diaspore, goethite, and limonite were used; Table 4 gives
the results of the tests for materials heated for three hours at 500°c.
The results for reagent grade ferric oxide and aluminum oxide powders are
also given in Table 4. In every case the heated materials showed higher
surface areas and superior strontium sorption properties than the unheated
materials. The amount of heated materials used was reduced according to
the respective weight loss; diaspore, goethite, and limonite required
0.22 8/50 ml and the gibbsite required 0.16 8/50 ml as compared with 0.25 8
of unheated materials per 50 ml of solution.
Limonite showed a relatively
high affinity for strontium even prior to heating, but the heat treatment
produced a superior sorbent 1f one takes into account the smaller sample
used in the test. The high selectivity by limonite in the natural state
was probably due to the initially high surface area. Like heat-treated
gibbsite, limonite functioned best in alkaline solutions.
Table 4. Percentage Sorption of Strontium by Several Materials
· From 0.1 M NaNO, Containing 1 x 10" M Sr2+
Heated Materials - 500°C for 3 hr
Sorption and pH for Specified Contact Time
1 hr
4 hr
24 hr
Surface Area
(mg)
36 hr
& PT
%
pH
=
pH
&
ĐT
6.6
68.5
16.3
72.8
9.85
9.45
17.3
84.0
9.90
9.80
18.6
85.7
9.70
9.75
17.4
84.7
9.65
9.20
62.1
Diaspore (325 mesh)
Unheated
Heated
Goethite (325 mesh)
Unbeated
Heated
Limonite (325 mesh)
Unheated
Heated
Gibbsite (powder)
Unbeated
Heated
15.8
95.5
9.80
9.75
18.3
97.6
9.70
9.75
17.8
98.1
9.80
9.80
17.7
97.3
9.60
9.60
20.8
93.2
84.2
98.2
9.70
8.95
94.4
99.6
9.80
9.60
97.8
99.7
9.60
9.70
98.2
99.6
9.60
9.15
0.3
177.0
1.01
99.5
9.80
9.95
2.77
99.66
9.84
9.85
99.8
9.83
0.15 9.50
99.81 9.80
Fe2O3
Unheated powder
33.8
9.75
40.3
9.90
41.9
9.80
41.8
8.85
A1293
Unbeated powder
C
6.6
32.9
49.1
-
66.6
Sample pH adjusted to 11.0 and not measured after contact.
Practical Application
Intermediate-level and high-level was tes contain varying concentra.
tions of stable salts, such as sodium nitrate. The potential usefulness
of high-surface alumina in waste treatment 18 Indicated in Fig. 4. Above
0.1 M NaNO2, the K, for strontium decreases rapidly for Dowex 50 resin
and the zeolitic mineral (clinoptilolite). At 1 M concentration, for
example, the K, 18 less than 300 for these ion exchangers, whereas the
F-20 grade alumina from the Aluminum Company of America has a K, of 4000.
It should be mentioned that these tests were performed at pH 10 and with
10
M Sr(NO2), concentration. The ion exchange capacity of the F-20
alwina was approximately 10 meq/100 8; the Dowex 50 was 500 meg/100 8
on the dry basis; and the clinoptilolite measured 80 meg/100 g.
To date, intermediate-level-activity waste at Oak Ridge National
Laboratory 1s disposed of in underground trenches. To assess the potential
hazard of such an operation, it is desirable to know the nature of reten-
tion of the radiostrontium. Samples of Conasauga shale taken near the
area of the trenches gave adsorption values above those of reference clay
minerals for this radioelement. The higher adsorption was suspected to
Fig. 4. The Influence of Sodium Nitrate Concentration on the Sorp-
tion of Radios trontium.
on
ORNL-OWG 63-5011R

...
a
..
A ALUMINA
O CLINOPTILOLITE
• DOWEX 50
o
N
o
Ko , DISTRIBUTION COEFFICIENT (mi/g)
N
o
Hoto ITI.
N
W
o
o
n
indinitis
ô
0
1
5
.
6
2
..
NaNO, CONCENTRATION (M)
be caused by the sesquioxides, particularly iron oxide, in the shale,
When the iron oxides were removed, the residual shale gave adsorption
values comparable to those obtained from 11lite from Illinois.
It was
estimated that about 50% of the adsorbed strontium was on the sesquioxides.
The results suggest close attention be paid to the på and dissolved salt
concentrations in the contaminated shale since these factors strongly
influence the adsorption properties of the sesquioxides.
In other tests
adsorption of iron oxide on the surface of acid-washed sand particles
-
-
-
-
-
-
-
resulted in an increase in strontium sorption from 26% on the sand to
88% when the sand contained 0.25% Fe Oz. These results further point to
the importance of the sesquioxides in soils as sorbents for strontium,
CEMENT SUSPENDERS
Chemical Development
In the development of slurries for use in the hydrofracturing method
of disposal, it was necessary to add a material which would suspend the
cement particles, adsorb the excess fluid, and reduce the over-all cost
of the formulation. In normal cement practices, bentonite 18 commonly
used to meet these requirements. The problem in our situation was
25
complicated by the nature of the waste solution which currently is 0.5 M
with respect to sodium lons and 18 expected to be 5 M as a new evaporator
18 Introduced in the waste treatment process.
It should be mentioned that
the total solids added to the waste 18 approximately 6 10/gal, and this
low solid/solution ratio makes it difficult to maintain a homogeneous
Buspension. In these waste solutions bentonite flocculates and 18 rela-
tively ineffective, as shown in Fig. 5. When the addition of bentonite
in the blend was increased, no improvement was noted (Fig. 5).
The reason
for this was that the slurry increased in volume proportionately and a
smaller proportion of the slurry was poured in the graduate.
Attapulgite clays have been reported to have viscosity and thixotropic
characteristics relatively imune to large variations in salt content
(Grim, 1963). Of several attapulgite samples tested, attapulgite 150*,
used in drilling muds, 18 effective as a suspender, adsorber, and as a
cheap substitute. Excess liquid not trapped in the matrix or adsorbed
on the clay or cement appears as "free" 11quid (Fig. 5). To minimize any
*The term 1s proprietary.
-
Fig. 5. Comparative Behavior of Mixes Containing Attapulgite (a)
and Montmorillonite (b) as suspenders. Increasing the solids containing
montmorillonite by 50% (c) and by 100% (a) did not improve phase separa-
tion, because the slurry volumes increased proportionately.
US
2
-

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hazardous consequence of phase separation, as this phenomenon is called,
111ite is added to selectively sorb cesium which is the most abundant
11
radionuclide in our intermediate-level waste stream, thus leaving any
GXC088 fluid relatively free of radioactivity.
Practical Application
Thus far, seven test injections have been completed. All tests con-
tained attapulgite at about 100 8/11ter for the reasons mentioned above.
The last three injections contained 11lite at 50 8/1iter for radiocesium
retention.
It is planned in future tests to include heat-treated gibbsite
or bauxite for improving radiostrontium retnetion. Routine use of
attapulgite is anticipated as the operations of the plant become an integral
--
-
--
part of the over-all waste disposal scheme at ORNL in 1966.
-
-
-
---
--
-
SUMMARY
Clay minerals and allied products have a vital role in the disposal
of radioactive wastes.
Illite is routinely used in large-scale waste
water treatment operations. Studies on the nature of the waste-clay re-
action have led to improving 1111te by heat treatment, as well as the use
of different clay minerals for radiocesium sorption. The sesquioxides
appear particularly attractive for radiostrontium sorption in solutions
of high salt content. Laboratory tests indicate that the besquioxides
in natural formations can contribute to radiostrontium sorption and aid
in its retention in the environment.
Attapulgite has been useful in
developing inexpensive mixes for disposal of intermediate-level wastes.
The high selectivity for radiocesium exhibited by minerals such as
1111te is related to the minimal 001 spacing of 2:1 layer silicates.
The
high sorption of radiostrontium by alumina 16 due to the high surface area
produced upon heating of the hydrated forms. Since illites, micas, and
the sesquioxides are ubiquitous in their distribution, these materials
are valuable economic materials for waste disposal applications.
REFERENCES
Amphlett, C. B. (1961) Treatment and disposal of Radioactive Wastos.
Pergamon Press, New York, 1961.
Cowser, K. E., and Tamura, T. (1963) Significant results in low-level
Waste treatments at ORNL, Health Physics v. 9, pp. 687-696.
Davis, W., Jr., Kibbey, A. H., and Schonfeld, E. (1965) Laboratory de.
monstration of the two-step process for decontaminating low-radio-
activity-level process waste water by scavenging-precipitation and
foam separation, Oak Ridge National Laboratory, OR
nal Laboratory, ORNI-3811.
de Laguna, W., and Houcor, B. L. (1960) Disposal of radioactive waste
: by hydraulic fracturing, Health Physics Division Annual Progress
Report, 1960, ORNL-2994, pp. 128-136.
Frederiksson, L., Ericksson, B., Rasmus on, B., Gahne, B., Edvarson, K.,
and Low, K. (1958) Studies on soil-plant-animaí interrelationships
with respect to fission products, Proc. Second U. N. Intern. Conf.
Peaceful Uses of Atomic Energy, September 1-13, 1958, Geneva:
United Nations, v. 18, pp. 449-470.
Grim, R. E. (1963) Some industrial applications of fundamental clay
mineralogy: Intern. Clay Conf. (Proc. of conference held at Stock-
holm, Sweden, Aug. 12-16, 1963), v. 2, pp. 389-398.
Jackson, M. L. (1958) Soil Chemical Analysis. Prentice-Hall, Englewood
cliffs, New Jersey (Ch. 4, pp. 6264).
Jackson, M. L., Hseung, Y., Corey, R. B., Evans, E. J., and Vanden Heuvel,
R. C. (1952) Weathering sequence in soil clays, Proc. Soil Sci Soc.
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Jacobs, D. G., and Tamura, T. (1960) The mechanism of lon fixation using
radioisotope techniques, Seventh Intern. Congr. Soil Sci., v. 2,
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Mawson, C. A. (1965) Management of Radioactive Wastes. Van Nostrand,
Princeton, New Jersey, 1965.
Parker, F. L., and Blanco, R. E. (1964 Waste treatment and disposal
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On the soil chem-
Schulz, R. K., Overstreet, R., and Barshad, I. (1960)
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30
Tamura, T. (1963) Cesium sorption reactions as indicator of clay mineral
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Tamura, T. (1964) Selective sorption reactions of cesium with soil min-
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Tamura, T., and Jacobs, D. G. (1960) Structural implications in cesium
sorption, Health Physics v. 2, pp. 391-398.
Tamura, T., and Jacobs, D. G. (1961) Improving cesium selectivity of
bentonites by heat treatment, Health Physics v. 5, pp. 149-154.
Tamura, T., and Struxness, E. G. (1963) Reactions affecting strontium
removal from radioactive wastes, Health Physics v. 9, pp. 697-704.
Yoder, H. S., and Eugster, H. P. (1955) Synthetic and Natural Muscovites:
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