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

118 Pages·2011·3.11 MB·English
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Preview Geochemical Behavior of Long-Lived Radioactive Wastes QAK^RIDGE NATIONAL LABORATORY

O R N L - T M - 4 4 8 1 Geochemical Behavior of Long-Lived Radioactive Wastes Ferruccio Gera Vi 1®§ C} - ' f q ( iK^ 1 taT* * T V':' F a 1 O ' r \ \ V sr.^ < ^ 1 VJ.* ' ' " ' v ' "^ , P^c: QAK^RIDGE NATIONAL LABOi R•> ATORY . OPERATED BY U N I O N CARBIDE CORPORATION • FOR THE U S ATOMIC E N E R G Y C O M M I S S I O N ^ ML , : 0.:: aw; •KV. W- 1 > * V ... * .. .A. V Printed in the United States of America. Available from National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road, Springfield, Virginia 22161 Price: Printed Copy $5.45; Microfiche $2.25 This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the Energy Research and Development Administration, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. 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.

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