TENORM Sources: Summary Table

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1 Sources: Summary Table Radiation Protection US EPA 1 of 3 9/14/ :33 AM Recent Additions Contact Us Print Version Search: EPA Home > Radiation > Programs > > Sources: Summary Table Radiation Home News Information Topics Programs Visitors'Center Site Map Radiation Home Home Basic Information Frequent Questions Sources Working With Other Organizations Regional Contacts Glossary Publications Laws & Regulations Guidance Related Links Sources: Summary Table The summary table below provides a range of reported concentrations, and average concentration measurements of Naturally-Occurring Radioactive Materials (NORM) that become concentrated in various wastes and materials. Once the NORM is concentrated or exposed by human activities, such as mining, it is classified as (Technologically-Enhanced, Naturally-Occurring Radioactive Materials).This is not a comprehensive list, as radiation is known to occur in many other materials, but should provide a general sense of the hazards posed by this class of radioactive substances. Source: Note: Unless otherwise noted, the radiation level of each waste is shown in the units pci/gram. For comparison purposes, the average level of radium in soil ranges from less than 1 to slightly more than 4 pci/gram. "NA" indicates data is not available. Radiation Level [pci/g] low average high Soils of the United States 0.2 NA 4.2 Geothermal Energy Waste Scales (fact sheet) Oil and Gas Production Wastes (fact sheet) Produced Water [pci/l] 0.1 NA 9,000 Pipe/Tank Scale <0.25 <200 >100,000 Water Treatment Wastes (fact sheet) Treatment Sludge [pci/l] ,686 Treatment Plant Filters NA 40,000 NA Waste Water Treatment Wastes (fact sheet) Treatment Sludge [pci/l] Programs WIPP Oversight Yucca Mtn. Standards Mixed Waste Federal Guidance Naturally Occurring Radioactive Materials Radon Radionuclides in Water SunWise Rad NESHAPs Regional Programs MARSSIM MARLAP Cleanup: Technologies & Tools Risk Assessment Radiation Emergency Response Clean Materials Laboratories

2 Sources: Summary Table Radiation Protection US EPA 2 of 3 9/14/ :33 AM Source: Radiation Level [pci/g] Treatment Plant Ash [pci/l Aluminum Production Wastes (fact sheet) Ore (Bauxite) 4.4 NA 7.4 Product 0.23 Production Wastes NA NA Coal and Coal Ash (fact sheet) Bottom Ash Fly Ash Copper Production Wastes ( fact sheet) Fertilizer Production Wastes (fact sheet) Ore (Florida) Phosphogypsum Phosphate Fertilizer Gold and Silver Extraction Wastes ( fact sheet) Rare Earths (Monazite, Xenotime, Bastnasite) Extraction Wastes (fact sheet) 5.7 NA 3224 Titanium Production Wastes (fact sheet) Rutile 19.7 NA Ilmenite NA 5.7 Wastes Uranium Mining Wastes (fact sheet) Uranium Mining Overburden Uranium In-Situ Leachate Evaporation Pond low hundreds Solids 300 Zircon Extraction Wastes (fact sheet)

3 Sources: Summary Table Radiation Protection US EPA 3 of 3 9/14/ :33 AM Source: Radiation Level [pci/g] 68 Wastes [Top of Page ] Radiation Home News Topics Information Programs Visitors' Center Site Map EPA Home Privacy and Security Notice Contact Us Last updated on Friday, April 27th, 2007 URL:

4 Aluminum Production Wastes Radiation Protection US EPA 1 of 2 9/14/ :34 AM Recent Additions Contact Us Print Version Search: EPA Home > Radiation > Programs > > Aluminum Production Wastes Radiation Home News Information Topics Programs Visitors'Center Site Map Radiation Home Home Basic Information Frequent Questions Sources Working With Other Organizations Regional Contacts Glossary Publications Laws & Regulations Guidance Related Links Aluminum Production Wastes Waste muds created by the extraction of alumina from its ore, bauxite, may contain low levels of Naturally-Occurring Radioactive Materials (NORM) usually: uranium thorium radium their radioactive decay products. The NORM becomes concentrated in the production wastes, which are then classified as (Technologically-Enhanced Naturally-Occurring Radioactive Materials). Source Radiation Level [pci/g] low average high Ore (Bauxite) 4.4 NA 7.4 Product 0.23 Production Wastes NA NA Radiation in Summary Table The only ore beneficiation operations performed at these bauxite mines include crushing and grinding. Water used for dust suppression, mine dewatering, and surface runoff results in the generation of a small volume of wastewater. This water is neutralized by lime and then discharged into nearby streams (EPA78a). Bauxite refineries produce alumina (Al2O3) which is used primarily as a feedstock for the aluminum reduction industry. In 1989, five facilities in the United States engaged in domestic alumina production (EPA90). The locations and ore sources for these facilities are shown in Table B.7-4. The total annual production capacity for the domestic bauxite refining industry, as reported by these facilities, was approximately 4.9 million MT. The total reported 1988 production of alumina was 4.1 million MT, which was about 84 percent of U.S. capacity (EPA90). Bauxite ore is processed at an alumina plant using the Bayer or modified Bayer processes. Dried bauxite is mixed with a Programs WIPP Oversight Yucca Mtn. Standards Mixed Waste Federal Guidance Naturally Occurring Radioactive Materials Radon Radionuclides in Water SunWise Rad NESHAPs Regional Programs MARSSIM MARLAP Cleanup: Technologies & Tools Risk Assessment Radiological Emergency Response Clean Materials Laboratories

5 Aluminum Production Wastes Radiation Protection US EPA 2 of 2 9/14/ :34 AM caustic liquor in slurry tanks, transferred to heated digesters where additional caustic is added to dissolve the alumina from the bauxite. The alumina can then be further processed, transferred, or sold to another facility. The liquor is then pumped through settling tanks to remove the bauxite residue. This spent bauxite residue, called "red mud", is placed in a tailings impoundment near the plant. Red mud in some plants is further processed to remove sodium aluminum silicate in the form of pure chemical grade alumina hydrates. This waste product is called "brown mud". Hydrated aluminum oxide is precipitated from the liquor and heated in rotary kilns to drive off water to produce aluminum oxide. The refinery muds (both red and brown mud) dry to a solid with very fine particle size (about 1 μm) and contain significant amounts of iron, aluminum, calcium, and sodium. They may also contain trace amounts of elements, such as barium, boron, cadmium, chromium, cobalt, gallium, lead, scandium, and vanadium, as well as NORM. The types and concentrations of minerals present in the muds depend on the composition of the ore and processing conditions. The material is caustic and no secondary use has been made of the impounded muds. The EPA has identified elevated arsenic (16μg/g) and chromium (374 μg/g) concentrations in some mud samples (EPA 90). However, muds might be used for land reclamation, for the construction of site dams or embankments, or as a feed material for other extraction processes because of the high iron content (20 to 50 percent). Radiation Home News Topics Information Programs Visitors' Center Site Map EPA Home Privacy and Security Notice Contact Us Last updated on Wednesday, November 15th, 2006 URL:

6 Coal Mining Wastes and Coal Ash Radiation Protection US EPA 1 of 2 9/14/ :34 AM Recent Additions Contact Us Print Version Search: EPA Home > Radiation > Programs > >Coal Mining Wastes and Coal Ash Radiation Home News Information Topics Programs Visitors'Center Site Map Radiation Home Home Basic Information Frequent Questions Sources Working With Other Organizations Regional Contacts Glossary Publications Laws & Regulations Guidance Related Links Coal Ash Coal contains trace quantities of the naturally occurring radionuclides: uranium thorium potassium their radioactive decay products including radium. The presence of radium in coal is known to vary over two orders of magnitude depending upon the type of coal and region from which it has been mined. When coal is burned, minerals including most of the radionuclides do not burn and as a result are concentrated in the ash. Coal ash generally consists of fly ash, bottom ash, and boiler slags. Utility and industrial boilers are estimated to generate about 61 million metric tons (MT) of coal ash per year. Of this total amount, nearly 20 million MT are used in a variety of applications instead of being sent to disposal facilities, primarily: additive in concrete structural fill road construction. The amount of ash generated during combustion is primarily dependent upon the mineral content of the coal and type of boiler. The table below lists typical radiation levels in coal ash: Wastes Radiation Level [pci/g] low average high Bottom Ash Fly Ash Programs WIPP Oversight Yucca Mtn. Standards Mixed Waste Federal Guidance Naturally Occurring Radioactive Materials Radon Radionuclides in Water SunWise Rad NESHAPs Regional Programs MARSSIM MARLAP Cleanup: Technologies & Tools Risk Assessment Radiological Emergency Response Clean Materials Laboratories Radiation in Summary Table

7 Coal Mining Wastes and Coal Ash Radiation Protection US EPA 2 of 2 9/14/ :34 AM Radiation Home News Topics Information Programs Visitors' Center Site Map EPA Home Privacy and Security Notice Contact Us Last updated on Wednesday, November 15th, 2006 URL:

8 U.S. Geological Survey Fact Sheet FS October, 1997 Introduction Radioactive Elements in Coal and Fly Ash: Abundance, Forms, and Environmental Significance 900 Coal is largely composed of organic matter, but it is the inorganic matter in coal minerals and trace elements that have been cited as possible causes of health, environmental, and technological problems associated with the use of coal. Some trace elements in coal are naturally radioactive. These radioactive elements include uranium (U), thorium (Th), and their numerous decay products, including radium (Ra) and radon (Rn). Although these elements are less chemically toxic than other coal constituents such as arsenic, selenium, or mercury, questions have been raised concerning possible risk from radiation. In order to accurately address these questions and to predict the mobility of radioactive elements during the coal fuel-cycle, it is important to determine the concentration, distribution, and form of radioactive elements in coal and fly ash. Abundance of Radioactive Elements in Coal and Fly Ash Assessment of the radiation exposure from coal burning is critically dependent on the concentration of radioactive elements in coal and in the fly ash that remains after combustion. Data for uranium and thorium content in coal is available from the U.S. Geological Survey (USGS), which maintains the largest database of information on the chemical composition of U.S. coal. This database is searchable on the World Wide Web at: CoalQual/intro.htm. Figure 1 displays the frequency distribution of uranium concentration for approximately 2,000 coal samples from the Western United States and approximately 300 coals from the Illinois Basin. In the majority of samples, concentrations of uranium fall in the range from slightly below 1 to 4 parts per million (ppm). Similar uranium concentrations are found in a variety of common rocks and soils, as indicated in figure 2. Coals with more than 20 ppm uranium are rare in the United States. Thorium concentrations in coal fall within a similar 1 4 ppm range, compared to an average crustal abundance of approximately 10 ppm. Coals with more than 20 ppm thorium are extremely rare. During coal combustion most of the uranium, thorium, and their decay products are released from the original coal matrix and are distributed between the gas NUMBER OF OBSERVATIONS NUMBER OF OBSERVATIONS Western United States (2,3) (4,5) (6,7) (8,9) (10,11) (12,13) (14,15) (1,2) (3,4) (5,6) (7,8) (9,10) (11,12) (13,14) >15 URANIUM CONCENTRATION IN WHOLE COAL (ppm) (2,3) (4,5) (6,7) (1,2) (3,4) (5,6) (7,8) Illinois Basin (8,9) (10,11) (12,13) >15 (9,10) (11,12) (13,15) URANIUM CONCENTRATION IN WHOLE COAL (ppm) Figure 1. Distribution of uranium concentration in coal from two areas of the United States. phase and solid combustion products. The partitioning between gas and solid is controlled by the volatility and chemistry of the individual elements. Virtually 100 percent of the radon gas present in feed coal is transferred to the gas phase and is lost in stack emissions. In contrast, less volatile elements such as thorium, uranium, and the majority of their decay products are almost entirely retained in the solid combustion wastes. Modern power plants can recover greater than 99.5 percent of the solid combustion wastes. The average ash yield of coal burned in the United States is approximately 10 weight percent. Therefore, the concentration of most radioactive elements in solid combustion wastes will be approximately 10 times the concentration in the original coal. Figure 2 illustrates that the uranium concentration of most fly ash (10 to 30 ppm) is still in the range found in some granitic rocks, phosphate rocks, and shales. For example,

9 Basaltic rock U.S. coals Common shales Granitic rock Fly ash = 10x U.S. coals Black shales URANIUM CONCENTRATION (ppm) Phosphate rock Figure 2. Typical range of uranium concentration in coal, fly ash, and a variety of common rocks. the Chattanooga Shale that occurs in a large portion of the Southeastern United States contains between 10 and 85 ppm U. Forms of Occurrence of Radioactive Elements in Coal and Fly Ash The USGS has a current research project to investigate the distribution and modes of occurrence (chemical form) of trace elements in coal and coal combustion products. The approach typically involves (1) ultra sensitive chemical or radiometric analyses of particles separated on the basis of size, density, mineral or magnetic properties, (2) analysis of chemical extracts that selectively attack certain components of coal or fly ash, (3) direct observation and microbeam analysis of very small areas or grains, and (4) radiographic techniques that identify the location and abundance of radioactive elements. Most thorium in coal is contained in common phosphate minerals such as monazite or apatite. In contrast, uranium is found in both the mineral and organic fractions of coal. Some uranium may be added slowly over geologic time because organic matter can extract dissolved uranium from ground water. In fly ash, the uranium is more concentrated in the finer sized particles. If during coal combustion some uranium is concentrated on ash surfaces as a condensate, then this surface-bound uranium is potentially more susceptible to leaching. However, no obvious evidence of surface enrichment of uranium has been found in the hundreds of fly ash particles examined by USGS researchers. The above observation is based on the use of fission-track radiography, a sophisticated technique for observing the distribution of uranium in particles as small as centimeter in diameter. Figure 3 includes a photograph of a hollow glassy sphere of fly ash and its corresponding fission track image. The diameter of this relatively large glassy sphere is approximately 0.01 cm. The distribution and concentration of uranium are indicated by fission tracks, which appear as dark linear features in the radiograph. Additional images produced by USGS researchers from a variety of fly ash particles confirm the preferential location of uranium within the glassy component of fly ash particles. Health and Environmental Impact of Radioactive Elements Associated With Coal Utilization Radioactive elements from coal and fly ash may come in contact with the general public when they are dispersed in air and water or are included in commercial products that contain fly ash. The radiation hazard from airborne emissions of coalfired power plants was evaluated in a series of studies conducted from These studies concluded that the maximum radiation dose to an individual living within 1 km of a modern power plant is equivalent to a minor, perhaps 1 to 5 percent, increase above the radiation from the natural environment. For the average citizen, the radiation dose from coal burning is considerably less. Components of the radiation environment that impact the U.S. population are illustrated in figure 4. Natural sources account for the majority (82 percent) of radiation. Man-made sources of radiation are dominated by medical X-rays (11 percent). On this plot, the average population dose attributed to coal burning is included under the consumer products category and is much less than 1 percent of the total dose. Fly ash is commonly used as an additive to concrete building products, but the radioactivity of typical fly ash is not significantly different from that of more conventional concrete additives or other building materials such as granite or red brick. One extreme calculation that assumed high proportions of fly-ash-rich concrete in a residence suggested a dose enhancement, compared to normal concrete, of 3 percent of the natural environmental radiation. Another consideration is that low-density, fly-ashrich concrete products may be a source of radon gas. Direct measurement of this contribution to indoor radon is complicated by the much larger contribution from underlying soil and rock (see fig. 4). The emanation of radon gas from fly ash is less than from natural soil of

10 Figure 3. Photograph (left) of a hollow glassy fly ash particle (0.01 cm diameter) and its fission track radiograph (right). Uranium distribution and concentration are indicated by the location and density of dark linear fission tracks in the radiograph. NATURAL COSMIC 8% TERRESTRIAL 82% 8% INTERNAL 11% RADON 55% MAN-MADE MEDICAL X rays 11% 4% 3% 18% Nuclear Medicine CONSUMER PRODUCTS OTHER <1% Figure 4. Percentage contribution of various radiation sources to the total average radiation dose to the U.S. population. similar uranium content. Present calculations indicate that concrete building products of all types contribute less than 10 percent of the total indoor radon. Approximately three-fourths of the annual production of fly ash is destined for disposal in engineered surface impoundments and landfills, or in abandoned mines and quarries. The primary environmental concern associated with these disposal sites is the potential for groundwater contamination. Standardized tests of the leachability of toxic trace elements such as arsenic, selenium, lead, and mercury from fly ash show that the amounts dissolved are sufficiently low to justify regulatory classification of fly ash as nonhazardous solid waste. Maximum allowable concentrations under these standardized tests are 100 times drinking water standards, but these concentration limits are rarely approached in leachates of fly ash. The leachability of radioactive elements from fly ash has relevance in view of the U.S. Environmental Protection Agency (USEPA) drinking water standard for dissolved radium (5 picocuries per liter) and the proposed addition of drinking water standards for uranium and radon by

11 the year Previous studies of radioelement mobility in the enviroment, and in particular, in the vicinity of uranium mines and mills, provide a basis for predicting which chemical conditions are likely to influence leachability of uranium, barium (a chemical analog for radium), and thorium from fly ash. For example, leachability of radioactive elements is critically influenced by the ph that results from reaction of water with fly ash. Extremes of either acidity (ph<4) or alkalinity (ph>8) can enhance solubility of radioactive elements. Acidic solutions attack a variety of mineral phases that are found in fly ash. However, neutralization of acid solutions by subsequent reaction with natural rock or soil promotes precipitation or sorption of many dissolved elements including uranium, thorium, and many of their decay products. Highly alkaline solutions promote dissolution of the glassy components of fly ash that are an identified host of uranium; this can, in particular, increase uranium solubility as uranium-carbonate species. Fortunately, most leachates of fly ash are rich in dissolved sulfate, and this minimizes the solubility of barium (and radium), which form highly insoluble sulfates. Direct measurements of dissolved uranium and radium in water that has contacted fly ash are limited to a small number of laboratory leaching studies, including some by USGS researchers, and sparse data for natural water near some ash disposal sites. These preliminary results indicate that concentrations are typically below the current drinking water standard for radium (5 picocuries per liter) or the initially proposed drinking water standard for uranium of 20 parts per billion (ppb). Summary Radioactive elements in coal and fly ash should not be sources of alarm. The vast majority of coal and the majority of fly ash are not significantly enriched in radioactive elements, or in associated radioactivity, compared to common soils or rocks. This observation provides a useful geologic perspective for addressing societal concerns regarding possible radiation and radon hazard. The location and form of radioactive elements in fly ash determine the availability of elements for leaching during ash utilization or disposal. Existing measurements of uranium distribution in fly ash particles indicate a uniform distribution of uranium throughout the glassy particles. The apparent absence of abundant, surfacebound, relatively available uranium suggests that the rate of release of uranium is dominantly controlled by the relatively slow dissolution of host ash particles. Previous studies of dissolved radioelements in the environment, and existing knowledge of the chemical properties of uranium and radium can be used to predict the most important chemical controls, such as ph, on solubility of uranium and radium when fly ash interacts with water. Limited measurements of dissolved uranium and radium in water leachates of fly ash and in natural water from some ash disposal sites indicate that dissolved concentrations of these radioactive elements are below levels of human health concern. Dr. Robert A. Zielinski, U.S. Geological Survey Denver Federal Center, Mail Stop 973 Denver, Colorado (303) ; rzielinski@usgs.gov Suggested Reading: Tadmore, J., 1986, Radioactivity from coal-fired power plants: A review: Journal of Environmental Radioactivity, v. 4, p Cothern, C.R., and Smith, J.E., Jr., 1987, Environmental Radon: New York, Plenum Press, 363 p. Ionizing radiation exposure of the population of the United States, 1987: Bethesda, Md., National Council on Radiation Protection and Measurements, Report 93, 87 p. Swaine, D.J., 1990, Trace Elements in Coal: London, Butterworths, 278 p. Swaine, D.J., and Goodarzi, F., 1997, Environmental Aspects of Trace Elements in Coal: Dordrecht, Kluwer Academic Publishers, 312 p. S. U. D EPA RT M E NT March O F 3, 1849 T H E I N TERI O R DEPARTMENT OF THE For more information please contact: U.S. GEOLOGICAL INTERIOR SURVEY Dr. Robert B. Finkelman, U.S. Geological Survey National Center, Mail Stop Sunrise Valley Drive, Reston, VA ; rbf@usgs.gov U.S. Department of the Interior U.S. Geological Survey Fact Sheet FS

12 Fertilizer Production Wastes Radiation Protection US EPA 1 of 3 9/14/ :35 AM Recent Additions Contact Us Print Version Search: EPA Home > Radiation > Programs > > Fertilizer Production Wastes Radiation Home News Information Topics Programs Visitors'Center Site Map Radiation Home Home Basic Information Frequent Questions Sources Working With Other Organizations Regional Contacts Glossary Publications Laws & Regulations Guidance Related Links Fertilizer and Fertilizer Production Wastes The phosphate ore used for the production of phosphate for fertilizers typically contains Naturally-Occurring Radioactive Materials (NORM), such as radium and other radionuclides and creates large amounts of radon. During the production of phosphoric acid, most of the radium ends up in process wastes, known as "phosphogypsum." Because the naturally-occurring radionuclides are concentrated in physphogypsum by human activity, it is a (Technologically-Enhanced Naturally-Occurring Radioactive Materials) waste. A small fraction of the radium accompanies the product, phosphoric acid, and ends up in commercial fertilizer. Phosphate Fertilizer The yearly consumption of fertilizers in the U.S. averaged close to 5 million metric tons (MT) between 1984 and While phosphate fertilizers are not assumed to be waste, they do contain some of the naturally-occurring radium (Ra-226) found in phosphate ores. The concentration of Ra-226 varies from five to 33 pico Curies per gram (pci/g), depending upon the type of fertilizer blend and the origin of the phosphate rock. The average Ra-226 concentration in fertilizers used in this assessment of the impact of their use on soil concentrations is 8.3 pci/g. Fertilizer application rates are known to vary depending upon the type of crops and soils. A typical phosphate fertilizer application rate is about 40 kg per hectare. Fertilizers are available in over 100 different blends with varying concentrations of nitrogen, phosphorus, and potassium. The resulting increase in soil concentrations of Ra-226 is only on the order of pci/g for 20 years of repeated fertilizer applications. By comparison, natural soils contain radium in concentrations ranging from 0.1 to 3 pci/g. Source Radiation Level [pci/g] low average high Phosphate Fertilizer Programs WIPP Oversight Yucca Mtn. Standards Mixed Waste Federal Guidance Naturally Occurring Radioactive Materials Radon Radionuclides in Water SunWise Rad NESHAPs Regional Programs MARSSIM MARLAP Cleanup: Technologies & Tools Risk Assessment Radiological Emergency Response Clean Materials Laboratories Fertilizer Production Wastes Phosphogypsum is a the primary byproduct of the wet-acid

13 Fertilizer Production Wastes Radiation Protection US EPA 2 of 3 9/14/ :35 AM process for producing phosphoric acid from phosphate rock. It is largely calcium sulfate and has been given the name phosphogypsum. (Gypsum is the common trade name for calcium sulfate, a common building material.) Phosphate production generates very large volumes of phosphogypsum, which is stored in huge piles called "stacks" that cover hundreds of acres in Florida and other phosphate-processing states. The table below shows the range of activity in fertilizer production wastes: Source Radiation Level [pci/g] low average high Phosphate Ore (Florida) Phosphogypsum Radiation in Summary Table Since there are large quantities of phosphogypsum waste, the industry encourages its use in order to minimize the disposal problem. Past and current uses of phosphogypsum include: agricultural: fertilizer and soil conditioner backfill for road construction concrete additive. The most use of phosphogypsum is in agricultural applications. Agricultural Phosphogypsum has been used in agriculture as a source of calcium and sulfur for soils that are deficient in these elements. When the phosphogypsum is used as a fertilizer, it is simply spread on the top of the soil. When used for ph adjustment or sediment control, it is tilled into the soil. The activity of phosphogypsum used for agricultural purposes may not exceed 10 pci/g. An estimated 221,000 metric tons of phosphogypsum are taken from the phosphogypsum stacks and used in agriculture each year (. There is no limitation on the amount of material that can be applied and farmers do not have to maintain certificates or application records. Road Construction Phosphogypsum was used previously in road construction. Currently, this use is banned under the EPA final rule issued on June 3, 1992, which amends 40 CFR 61 Subpart R (EPA92). New Uses In response to the need for new ways to make use of

14 Fertilizer Production Wastes Radiation Protection US EPA 3 of 3 9/14/ :35 AM phosphogypsum, EPA has provided a process by which researchers may apply for approval from EPA for new uses. In addition, the state of Florida has created an independent state research agency, Florida Institute of Phosphate Research (FIPR) charged with investigating ways to minimize adverse environmental impacts of the phosphate industry. Resources Rad-NESHAPs, Subpart R: Radon from Phophogypsum Stacks This site provides information on EPA's National Emission Standards for Hazardous Air Pollutants: Radionuclides that apply to radon emissions from phosphogypsum stacks. It also provides information on the formation of phosphogypsum, the stacks, and potential uses for the material. Radiation Home News Topics Information Programs Visitors' Center Site Map EPA Home Privacy and Security Notice Contact Us Last updated on Wednesday, November 15th, 2006 URL:

15 Geothermal Energy Production Waste Scales Radiation Protection US EPA 1 of 2 9/14/ :34 AM Recent Additions Contact Us Print Version Search: EPA Home > Radiation > Programs > > Geothermal Energy Production Waste Scales Radiation Home News Information Topics Programs Visitors'Center Site Map Radiation Home Home Basic Information Frequent Questions Sources Working With Other Organizations Regional Contacts Glossary Publications Laws & Regulations Guidance Related Links Geothermal Energy Production Waste Scales Using geothermal energy requires drilling deep holes (boreholes)and inserting pipes for pumping high-temperature fluids from the ground. The rocks that contain the high-temperature fluids may also contain minerals, which tend to form a scale inside the pipes and production equipment. If the rocks also contain radionuclides, such as radium, the mineral scale, production sludges, and waste water will contain. Geothermal energy currently makes a relatively minor contribution to total U.S. energy production. The primary geothermal development sites in the U.S. are the Geysers, in Sonoma County in northern California, and the Imperial Valley in southern California. The only significant wastes from geothermal power production are the solid wastes originating from the treatment of spent brines such as in Imperial Valley. The hot saline fluids from geothermal reservoirs in that area may have a dissolved solids content approaching 30 percent by weight. The estimated annual generation rate of geothermal energy production waste is 54 thousand metric tons. Because of unsuitable physical characteristics, solid geothermal wastes are not reused, but disposed of in solid waste landfills. A few facilities are also considering process of these wastes to extract valuable minerals (gold, sliver, and platinum). The table below shows the estimated average activity in geothermal wastes, based on data from southern California geothermal power production facilities: Wastes Geothermal Energy Waste Scales Radiation in Summary Table Radiation Level [pci/g] low average high Programs WIPP Oversight Yucca Mtn. Standards Mixed Waste Federal Guidance Naturally Occurring Radioactive Materials Radon Radionuclides in Water SunWise Rad NESHAPs Regional Programs MARSSIM MARLAP Cleanup: Technologies & Tools Risk Assessment Radiological Emergency Response Clean Materials Laboratories

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17 Oil and Gas Production Wastes Radiation Protection US EPA 1 of 2 9/14/ :33 AM Recent Additions Contact Us Print Version Search: EPA Home > Radiation > Programs > > Oil and Gas Production Wastes Radiation Home News Information Topics Programs Visitors'Center Site Map Radiation Home Home Basic Information Frequent Questions Sources Working With Other Organizations Regional Contacts Glossary Publications Laws & Regulations Guidance Related Links Oil and Gas Production Wastes The rocks that contain oil and gas deposits often contain water as well. The water dissolves minerals and radionuclides, such as radium, that are in the rocks. (These Naturally Occurring Radioactive Materials are commonly referred to as, NORM.) Radium and other radionuclides and their radioactive decay products become concentrated in production wastes: pipe scale that tends to form inside oil and gas production pipes and equipment large volumes of waste water sludges that accumulate in tanks or pits. These waste are classified as (Technologically-Enhanced, Naturally-Occurring Radioactive Materials). The types of waste generated by the petroleum industry include pipe scale, sludge, and equipment or components contaminated with radium. It is estimated that the industry generates about 150,000 cubic meters or 260,000 metric tons of such waste yearly. Field surveys have shown that petroleum pipe scale may have very high Ra-226 concentrations, in some cases more than 400,000 pci/g. Some of this waste is retained in oil and gas production equipment, while some of the scale and sludge is presently being removed and stored in drums. The industry disposes of scale and sludge wastes removed from oil and gas production equipment and also discards associated contaminated components. The table below shows the range of activities in these wastes: Wastes Radiation Level [pci/g] low average high Produced Water [pci/l] 0.1 NA 9,000 Pipe/Tank Scale <0.25 <200 >100,000 Radiation in Summary Table Programs WIPP Oversight Yucca Mtn. Standards Mixed Waste Federal Guidance Naturally Occurring Radioactive Materials Radon Radionuclides in Water SunWise Rad NESHAPs Regional Programs MARSSIM MARLAP Cleanup: Technologies & Tools Risk Assessment Radiological Emergency Response Clean Materials Laboratories

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19 Thorium Containing Welding Rod (1990s) 1 of 3 9/14/ :32 AM General Thorium Containing Welding Rod (1990s) Thoriated welding rods are used as electrodes in tungsten inert gas (TIG) welding in which the rod serves as a "nonconsumable" electrode. The rod is actually consumed during use, but it does not act as a filler that binds two pieces of metal together. The rate of consumption is approximately 0.1 to 0.3 mg/minute for typical currents but it can be as high as 50 to 60 milligrams per minutes for the maximum rated currents. This consumption probably involves volatilization and the loss of tiny droplets at the electrode tip. Because TIG welding is expensive, its is limited to those situations that require high quality results (e.g., the aircraft and petrochemical industries). By weight, the rods are usually 1 or 2 % thorium oxide (thoria) although higher concentrations, up to 4 %, have been used. The rods are color coded to indicate the thoria content: yellow indicates 1 %, and red indicates 2 %. The color usually appears as a band at one end of the rod (like that in the photo to the right). While they range from 0.25 to 6.35 mm in diameter and 7.6 to 61 cm long, a typical rod would be about 2.4 mm in diameter, 15 cm long, and contain 0.23 grams of thorium. Estimates over the last two decades put the annual production at 1 to 5 million electrodes. Thorium is added to the tungsten because it increases the current carrying capacity of the electrode and it reduces contamination of the weld. In addition, it is easier to start the arc and the latter is more stable. The radiological concern is the inhalation of airborne thorium. Thorium gets into the air because of the volatilization discussed earlier and the grinding that is necessary to put a point on the electrode prior to use. As a result of this concern, it is expected that the thorium in the rods will eventually be replaced by lanthanum or cerium oxide. Airborne Thorium Concentrations During welding operations, Ludwig et al measured thorium concentrations of < 7 x 10-9 to 5 x 10-6 uci/m 3 with a geometric mean of 3 x 10-8 uci/m 3. The concentrations measured during AC welding operations were approximately 30 times those measured during DC welding. Vinzents et al. measured a respirable concentration of 2 x 10-5 uci/m 3 during the grinding of rods with a 4

20 Thorium Containing Welding Rod (1990s) 2 of 3 9/14/ :32 AM % thorium content (the respirable fraction was 0.3). The conditions selected for the study were a worst case scenario. Ludwig et al reported an airborne concentration of 5 x 10-6 uci/m 3 during the grinding. Crim and Bradley reported 6.3 x 10-7 uci/m 3 while Jankovic et al reported 1.4 x 10-6 uci/m 3. Based on this data, NUREG-1717 concluded that a typical concentration during grinding was 2.3 x 10-6 uci/m 3. Dose Estimates Detailed dose estimates are described in NUREG The conclusion was that the maximum individual doses resulted from routine welding and grinding operations. The estimated doses due to transportation and distribution were relatively small. 1. Doses from grinding. The grinding of the rod to form a pointed end can take anywhere from 20 to 60 seconds depending on the skill of the grinder. For welders that grind their own rods, this can take a minute or even longer. Individuals who specialize in this activity can complete the task much quicker. At a large facility, e.g., with 50 welders, a grinder might handle as many as 150 rods per day (ca. 3 per day per welder). For the purpose of the calculations, NUREF-1717 assumed that the particle size AMAD was 1 um. An individual welder sharpening his own rods was estimated to receive 20 mrem per year. This would be reduced by a factor of ten or so if a local exhaust system was used. A dedicated grinder sharpening rods for 200 hours per year without the benefit of a local exhaust system was estimated to receive approximately 800 mrem. 2. Doses from Welding Operations As NUREG-1717 acknowledges, any estimation of the dose due to welding operations is highly speculative. Assumptions have to be made about the amount of thorium becoming airborne, the amount of time spent welding, the effect of the welder s mask, the ventilation rate, the size distribution of the particulates, etc. Assuming that 1000 hours per year were spent in actual welding operations, NUREG-1717 estimated that the dose would be 20 mrem per year for DC operations and 500 mrem per year for AC operations. These estimates assume that no local exhaust system was used. Should local exhaust be employed, the estimated doses would be a factor of ten or so lower. The external exposure due to beta particles and gamma rays was determined to be an insignificant fraction of the dose due to inhalation. 3. Dose from Carrying Welding Rods in Pocket The estimated effective dose equivalent to an individual carrying three thoriated welding rods (0.9 g thorium) in a shirt pocket for 2000 hours (40 hrs/week x 50 weeks/year) was 8 mrem.. Pertinent Regulations 10 CFR Unimportant quantities of source material (2003) (c) Any person is exempt from the regulation in this part and from the requirements for a license set forth in section 62 of the Act to the extent that such person receives, possesses, uses, or transfers:... (1) Any quantities of thorium contained in... (iii) welding rods, References

21 Thorium Containing Welding Rod (1990s) 3 of 3 9/14/ :32 AM Breslin, A.J., and Harris, W.B. Use of Thoriated Tungsten Electrodes in Inert Gas Shielded Arc Welding Investigation of Potential Hazard. American Industrial Hygiene Association Quarterly 13 (4); Ludwig, T., Schwab, D., Seitz, G., and Siekmann, H. Intakes of Thorium While Using Thoriated Tungsten Electrodes for TIG Welding. Health Physics 77 (4): ; NCRP. Radiation Exposure of the U.S. Population from Consumer Products and Miscellaneous Sources. NCRP Report No. 95; Nuclear Regulatory Commission. Systematic Radiological Assessment of Exemptions for Source and Byproduct Materials. NUREG June Radioactive Consumer Products Museum Directory Last updated: 07/25/07 Copyright 1999, Oak Ridge Associated Universities