Geochemical Behavior of Long-Lived Radioactive Wastes QAK^RIDGE NATIONAL LABORATORY

118 Pages·2011·3.11 MB·English

O R N L - T M - 4 4 8 1
Geochemical Behavior of
Long-Lived Radioactive Wastes
Ferruccio Gera
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This report was prepared as an account of work sponsored by the United States
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Administration, nor any of their employees, nor any of their contractors,
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ORNL-TM-4481
UC-70-VJaste Management
C o n t r a c t N o . W - 7 4 0 5 ~ e n g - 2 6
CHEMICAL TECHNOLOGY DIVISION
LIVED RADIOACTIVE WASTES
GEOCHEMICAL BEHAVIOR OF LONG
Ferruccio Gera
JULY 1975
-NOTICE-
Thtt iepo»t was prepared JI *n account of work
tportiored by the United SUte» Guiernmenr. Neither
the United State* noi the United States Energy
R«<Afch and Development Ad mi nitration, net any of
their employee*, nor any ot Ihett c e n t n e w s ,
tubcon m e l o n . ot their employee*, m*'«r» any
witr tn ty , t t p i e i i ol i n c h e d , ot tuumt «ny lepf
babiliiy ot tetpoiuibihty (or the accuracy, compkieneu
ot wefu lne* of any information, eppmtuc . prwluet ot
process disclosed, or lepretenti that i u ut r would not
infringe p n n i t l y owned right*.
OAK RIDGE NATIONAL LABORATORY
Oak Ridge, Tennessee 37830
operated by
UNION CARBIDE CORPORATION
for the
ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATION
iii.
TABLE 0¥ CONTENTS
Page
A b s t r a c t 1
1 . I n t r o d u c t i o n 2
2 . Heavy N u c l i d e s and Long-Term Hazard P o t e n t i a l 3
3 . Geochemica l Data 16
3 . 1 Mobilization of Uranium and Radium 21
3 . 2 Removal o f Uranium and Radium from Ground Water 23
3 . 3 Abundance o f N a t u r a l A l p h a - E m i t t e r s i n t h e H y d r o s p h e r e . . . . 24
3 . 4 T r a n s u r a n i u m Elements 29
4 . E n v i r o n m e n t a l Behav io r 35
4 . 1 T e r r e s t r i a l Ecosystems 38
4 . 2 A q u a t i c Ecosystems 4
4 . 3 Resuspension 48
4 . 4 High-Background Areas 62
4.5 Uranium Mil Tailings 6
5. Sumary and Conc lus ions 74
6. Acknowledgment . 7
7. R e f e r e n c e s 78
Apendix 9 1
BLANK PAGE
iv.
LIST OF TABLES
Table Page
1 Activity of Long-Lived Fission Products in High-Level Solid
Wastes from LWR and I2-IFBR Fuels 4
2 Properties of Heavy Radionuclides with Half-Lives Longer
Than 30 Days 6
3 Radioactivity of Heavy Nuclides in LWR High-Level Solid
Waste as a Function of Decay Time 7
4 Radioactivity of Heavy Nuclides in LMFBR High-Level Solid
Waste as a Function of Decay Time 8
5 Number of Limits of Annual Intake by Ingestion of Heavy
3
Nuclides in 1 cm of LWR High-Level Solid Waste as a Function
of Decay Time 9
6 Number of Limits of Annual Intake by Inhalation of Heavy
3
Nuclides in 1 cm of LWR High-Level Solid Waste as a Function
of Decay Time. 10
7 Number of Limits of Annual Intake by Ingestion of Heavy
3
Nuclides in 1 cm of LMFBR High-Level Solid Waste as a
Function of Decay Time 1
8 Number of Limits of Annual Intake by Inhalation of Heavy
3
Nuclides in 1 cm of LMFBR High-Level Solid Waste as a
Function of Decay Time 12
9 Concentration of Uranium and Thorium in Various Rocks 17
10 Content of Radium in Water and Deposits of Some Russian
Mineral Springs 25
1 Content of Uranium and Radium in Natural Waters 27
12 Plutonium Content in Waters of Volcanic Regions 30
13 Plutonium Content in Recent Volcanic Rocks and Minerals. . . . 31
14 Estimated Average Annual Internal Radiation Doses from
Natural Radioactivity in the United States 37
226
15 Typical Concentrations of Ra in Soil Excluding High-Back-
ground Areas 39
26 28
16 Activity of Ra and Th in Various Fods 40
V
Table Page
17 Relationship Between Dietary Intake and Concentration in
Soil of Radium and Plutonium 41
18 Factors Relevant to the Transfer of Heavy Elements in
Terestrial Fodchains 42
19 Concentrations of Heavy Elements in Various Compartments
of Aquatic Ecosystems 45
239
20 Concentration Factors of Pu in Marine Invertebrates and
Algae 47
21 Important Sources of Atmospheric Aerosols and Worldwide
Production. 50
22 Relative Erodibility of Soil Particles According to Size. . . 51
23 Maximum Theoretical Values for Time of Flight, Range, and
Height of Rise of Particles in the Atmosphere for a Wind
of 5 km/hr 52
24 Size Distribution of Particulate Matter Suspended in Air. . . 54
25 Uranium Concentrations in Air . . . 5
26 Thorium Concentrations in Air in the San Francisco Bay Area . 57
27 Thorium Concentrations in Air in Continental Areas of North
America 58
228
28 Gross Alpha and Ra Levels in Various Foods Collected on
the Kerala Coast 65
2.9 Radioactivity in Water, Tuba City Uranium Mill, May 1967. . . 70
30 Average Long-Lived Radioactivity in Air, Monument Valley
Uranium Mil, May 1968 70
31 '^Ra and Uranium in Ground Water, Mexican Hat Uranium Mill,
May 1968 72
32 Comparison of Potential Hazards Associated with a 100,000-
Year-Old High-Level Waste Repository and a Large Uranium
Mil Tailings Pile 73
1
GEOCHEMlCAL BEHAVIOR OF LONG-LIVED RADIOACTIVE WASTES
Ferruccio Gera
ABSTRACT
The hazard potential associated with the heavy elements
present in high-level radioactive waste decreases greatly in
the first few tens of thousands of years of decay; however,
further reduction in the hazard potential becomes extremely
slow after about 100,000 years. In the time period between
100,000 and 5 million years the hazard potential of high-
level waste is reduced by a factor of between 10 and 20.
Current evidence seems to indicate that if radioactive waste
containment were to fail after a period of 100,000 years or
more, some environmental contamination would result; however,
the contamination levels would be low. The radiological risk
would not be significantly different from that now existing
in various localities as a result of the accumulation of nat-
ural radioactive elements.
With the partial exception of radium, which is concen-
trated in the fruit of specific perennial plants, the long-
lived alpha-emitters are characterized by very low biologic
availability in terrestrial ecosystems. The biologic avail-
ability may be somewhat higher in aquatic ecosystems due to
the significant reconcentration factors in particular organ-
isms. Despite the fact that many of these elements are fre-
quently discussed as a group (e.g., the actinides or the
transuranics), significant differences of environmental be-
havior exist among them. Inhalation hazards are controlled
primarily by the efficiency of resuspension mechanisms.
Soil erosion by wind is more effective for particles be-
tween 50 and 500 )Jm. On the other hand, the pulmonary de-
position of particles larger than 10 vim is practically
negligible.
Natural high-background areas and the piles of uranium
mill tailings are instances of unusual accumulations of long-
lived alpha-emitters in surface materials. Data concerning
the levels of activity in foods grown on radioactive soils
seem to confirm the low biologic availability of the natural
radioactive elements. Surveys of uranium mill tailings in-
dicate little dispersal of the radioactive elements into the
environment; even though untreated tailings piles would
appear to be particularly vulnerable to resuspension of dust
particles by wind.