Search Documents

By L. Max Scott

[INTRODUCTION] The significance of gamma exposure to uranium miners has been recognized only in the last few years. Most ore deposits which have been underground mined, were 1% or less U308. Full-time mining of this grade ore can result in exposure exceeding 1 Rem per year. Several companies in Saskatchewan are planning to mine recently discovered ore bodies which contain ore pods in excess of 10% U308. The purpose of this paper is to present dose data which can be used to estimate gamma exposure from high-grade ore deposits, and to present mining techniques which will minimize miner exposure. [Dose Estimates] When one has a point source of radiation, the conventional laws of isotropic emission and the fall of dose with square of the distance, make dose calculations relatively easy. However, if one has an area source of infinite thickness, the assumption must be made that a uniform gamma flux is being emitted from all faces of the source (Figure 1). Dose from gamma emission would fall off only due to air attenuation up to such a distance at which the source can be considered to be a point source (usually 10 times the largest dimension of the source). For short distances, such as to the cab of ore-moving equipment, the dose reduction would be negligible. Assumptions: 1) Radium and gamma-emitting daughters are in secular equilibrium with uranium. 2) All gamma radiation is emitted from radium and its daughters. 3) Average gamma energy of 0.8 MeV. 4) Uranium ore has a linear attenuation coefficient of 0.212 cm-1, similar to that of Si02(sand). 5) Uranium ore density of 3.0 gm/cm3. 6) One curie of radium emits 6.84 x 1010 photon/sec(l). 7) One percent uranium ore contains 1 x 10-8 Ci/cm3 of radium. 8) Each MeV of 0.8 MeV photon results in a dose of 2.10[ ]10-3 mRem/hr. per MeV/cm2 -sec. 1) 9) Minimum ore depth 100 cm. 10) Linear attenuation coefficient instant for radium gamma of 0.374 cm -1 [ ] The photon flux from a radioactive slab is computed as follows: [Flux = photon/cm3 3(1) 2u S] [where, us is the linear absorption coefficient of s the source (uranium ore).] Thus, 1% uranium ore, in the form of an infinite slab, emits 1613 photon/cm2-sec, which results in a dose rate of 2.71 mRem/hr. Since the dose from an infinite slab is the same as a dose from an infinite radius right circular cylinder, the only correction needed from the above dose rate is for finite radius and point of dose above the end of the cylinder (Figure 2) [Dose = mRem/hr. {E2(bl) - E2(b3) - [(E2(b1sec[E] -E2(b3sec[E]]cos[O](1)]

Jan 1, 1981

By Kathleen Kreiss, A. James Ruttenber

INTRODUCTION Early in the morning of July 16, 1979, there was a breach in the earthen retaining dam of a tailings pond at the United Nuclear Corporation's (UNC's) Church Rock uranium mill. The acidified liquid and tailings slurry spilled through the damaged portion of the retaining wall into an arroyo that is a tributary to the Rio Puerco river system. The Rio Puerco runs through Gallup, New Mexico, and eventually crosses the New Mexico-Arizona border (Fig. 1). On its way to Gallup, the Rio Puerco and its tributaries pass through land with a checkerboard pattern of ownership, with portions owned or leased by the Navajos, individuals, the Bureau of Land Management, and the State. In terms of tailings liquid volume (3.6 x 108L; 94 million gal), the UNC spill ranks as one of the largest. The mass of solids released in the slurry (10.0 x 105 kg; 1 100 tons) appears to be close to the median for accidents of this kind, however [U.S. Nuclear Regulatory Commission (NRC), 1979]. The UNC first opened its Church Rock uranium mill in 1977 on land adjacent to acreage belonging to the Navajo tribe. The mill, which is next to the UNC Church Rock mine, is located approximately 16 km (10 miles) northeast of Gallup, New Mexico (Fig. 1). Gallup, a town of 18 000 people, is the closest population center. The region surrounding the plant site is sparsely populated by Navajos, at a density of approximately 5.8 persons/km2 (15 persons/sq mile). The UNC mill and mines employ approximately 650 persons, and the adjacent Kerr-McGee uranium mine employs about 300. The UNC mill normally processes 3.2 x 106kg/day (3 500 tons/day) of uranium ore, depositing the acidified tailings slurry in a series of three earthen holding ponds. The tailings ponds are located east of the pipeline arroyo that feeds into the Rio Puerco approximately 2.4 km (1.5 miles) from the southernmost tailings dam. The liquid portion of the tailings slurry evaporates in the ponds; hence, under normal conditions, there is no surface flow from the holding ponds to the arroyo. Both runoff from the plant site after heavy rains and possible seepage from the tailings ponds may deliver radionuclides to the arroyo-river system, however. The dam across the southernmost tailings pond was considered to be in keeping with the state of the art. However, the New Mexico Environmental Improvement Division (NMEID) had warned UNC about dangers of locating the pond over a heterogeneous geological formation. The state Engineer's Office approved of the site only after UNC agreed to strict design criteria. Others have pointed to dangers of constructing earthen dams for impoundment of uranium mill tailings (Carter, 1978). Causes of the dam break were multiple: the UNC mill filled the tailings pond to a level that exceeded permit criteria; the tailings pond was lined improperly; the dam was constructed using clay that was compacted excessively, resulting in cracking and subsequent seepage; and the unstable substrate beneath the dam permitted differential settling. The UNC Church Rock mine has continuously released dewatering effluent into the pipeline arroyo at a rate of 88.3 L/sec (1 400 gal/min) since 1968. Before 1975 this effluent was not treated; after 1975 it received precipitation treatment for removal of Ra-226. Radionuclides are also released into the river system through the dewatering of the Kerr-McGee uranium mine 1.6 km (1.0 mile) north of the UNC mill. During usual mining operations, approximately 227 L/sec (3 600 gal/min) are released into the pipeline arroyo and subsequently into the Rio Puerco. The Kerr-McGee mine began continuous release of dewatering effluent in January 1972. In 1974 Kerr-McGee began Ra-226 precipitation treatment of its dewatering releases, but NMEID data indicate that treatment has often been incomplete. The effluent from both mines has been responsible for transforming the downstream portion of the Rio Puerco from a sporadically dry riverbed into a continuously flowing stream and has contributed to the current levels of background radiation along the river system (Table 1). This paper will summarize the postspill monitoring efforts and relate the assessment of this spill to the general question of evaluating the health effects of nuclear fuel-cycle wastes. The data pertaining to the measurement of radionuclides in the Church Rock environment and the radionuclide concentrations in animals will appear in forthcoming reports. CHURCH ROCK HEALTH EFFECTS ASSESSMENT APPROACH The initial health effects evaluation involved identifying the radionuclides that were released into the river system from the tailings pond. Table 1 lists the State of New Mexico maximum permissible radionuclide concentrations for liquids released to unrestricted areas, the typical tailings liquid concentrations, and postspill river water concentrations. The tailings liquid contained comparatively high levels of Th-230, Ra-226, Pb-210, and Po-210--all of which, according to postspill river water samples, had exceeded the state maximum permissible concentrations (MPC) at one time or another. After the radionuclides in the tailings were identified, pathways through which humans could be exposed were clarified. Environmental monitoring data were then used to quantify the important pathways of human exposure. Water samples were collected from the river, from test wells dug near

Jan 1, 1981

By H. T. Miller, L. M. Scott

Radiation exposures in Uranium operations may result from external beta-gamma radiation emitted by Uranium and its progeny, internal exposure to alpha and beta radiation due to the inhalation and ingestion of Uranium ores, Radon gas, and Radon progeny in mine, mill, and laboratory atmospheres and from the contamination of environmental working surfaces and clothing by Uranium-bearing compounds and ore. This paper summarizes occupational experience with reference to the exploration, surface mining, underground mining, milling and transport of Uranium by one company in the U.S. and Canada.

Jan 1, 1981

By E. Viet Howard

During the recent expansion of precipitate copper production at the Chino Mines Division of Kennecott Copper Corporation, Santa Rita, New Mexico, local studies of the dump leaching process were intensified. As these studies progressed it became apparent that a reliable method for locating leach solutions within the dump was required, since the contact between leach solutions and the copper-bearing material would determine, in great part, the recovery of values. In the past, the problem of determining leach solution contact has been attacked by various methods, including destructive testing (dump dissection), indirect observation (such as chloride or dye tracers), and mathematical or laboratory model studies. These methods have not proved completely satisfactory for the studies now being developed. Investigation of methods for in situ observation of leach solutions led to consideration of radiation logging in drill holes, which are petro¬leum exploration and development techniques for locating fluids and measuring porosity in the subsurface. Standard oil field logging equipment was leased, modified, and tested. After successful testing, the equipment was purchased for additional studies. Applications and results of the methods are described in this paper.

Jan 1, 1968

By Thomas B. Borak, Keith J. Schiager, Janet A. Johnson

OBJECTIVES OF RADIATION MONITORING Monitoring is a tool used in the practice of radiation protection. The primary reasons for monitoring are to reduce radiation exposures to levels that are as low as reasonably achievable and to assure that no individual receives a dose exceeding the maximum individual dose limit. The documentation of radiation doses for legal, medical, or epidemiological reasons is a subordinate function of any monitoring program. The investment in radiation monitoring programs should be guided by four criteria: (1) the detection and avoidance of unnecessary exposures, (2) the magnitude of potential health risks, (3) the determination of combined doses and risks with adequate confidence, and (4) the verification of compliance with established limits. FIRST CRITERION: DOSE REDUCTION - DETECT AND CORRECT UNNECESSARY EXPOSURES The system of dose limitation advocated by the International Commission on Radiological Protection (ICRP, 1977), and subscribed to in a broad sense by various regulatory agencies, is comprised of three essential ingredients: (1) [justification] of any practice that produces radiation doses by some commensurate net benefit, (2) [optimization] of radiation control measures by reducing doses to levels that are as low as reasonably achievable, and (3) [limitation] of individual doses to preclude inequities and [moldistribution] of risks. All too often, only the third criterion - the limitation of individual doses to prescribed regulatory limits - is explicitly addressed in everyday radiation protection programs. The emphasis of most exposure control and monitoring efforts appears to be directed toward limiting and documenting individual doses that might approach the legal limit. The first two criteria, i.e. justification and optimization, should contribute to a rationale for allocating monitoring efforts. When applied to individuals, these criteria mean the detection and elimination of unnecessary exposures. This should be a high priority of any monitoring program. Measurements should be directed toward detecting inoperative or ineffective control measures, whether or not there is a risk of exceeding the individual dose limits. The ICRP recommends a procedure that can be used effectively to reduce unnecessary exposures. A n investigation level should be established at an exposure rate substantially lower than the regulatory limit, e.g. 30% of the limit (ICRP 26, 1977, p.33). Measurements obtained during routine monitoring that exceed the investigation level are evaluated with respect to cause and potential reduction. To be effective, the evaluation results should be formally recorded and conveyed both to management and to the workers involved. Although the investigation level recommended by the ICRP is based on a fixed exposure rate or derived air concentration, an equally effective evaluation program may be based on the investigation of a percentage of all measurements. For example, one might investigate the highest 5% or a random selection of all measurements. In any case, the objective is to detect and correct situations that are producing unnecessary exposures. SECOND CRITERION: MONITOR IN PROPORTION TO THE MAGNITUDE OF RISK The ICRP criteria apply generally to all radiation exposures. However, a second priority for monitoring programs should be established on the basis of the nature of the exposures and the magnitude of the health risks involved. Current practices in radiation protection are based on dose limits to specific organs and assessment of individual exposure pathways, with little consideration of the combined doses from various pathways. Although the intent of the ICRP recommendations was to limit the total dose to each critical organ, combined doses from external and internal sources are rarely determined. The recent recommendations of the ICRP (Publ. 26, 1977) are based on the limitation of total health risk from occupational radiation exposures. Implementation of this concept would necessarily require the measurement, calculation and summation of doses and concomitant risks to all organs of the body from all exposure pathways. The U.S. Environmental Protection Agency has taken the first step toward translating the ICRP recommendations into regulations. The proposed recommendations for Federal Radiation Protection Guidance for Occupational Exposures (USEPA, 1981) include provisions for summing the risk-weighted organ doses to determine compliance with an effective whole-body dose equivalent limit. Whether or not the proposed guidance is modified before final adoption, it seems clear that some version of dose summation and combined risk limitation will be included in future regulations. With this

Jan 1, 1981

By Hans Ehdwall

INTRODUCTION Investigations of radon and radon daughter concentrations in Swedish [non-uranium] mines started in the late 1960's. The first screening measurements showed that the average annual exposure to radon and radon daughter products was 4.7 WLM. The main reason for high radon and radon daughter concentrations was inefficient ventilation and radonrich water entering the mine. In the radon regulations worked out later it was stated that no miner should be exposed to more than 60 000 pCi h/1 equilibrium equivalent concentration of radon annual exposure, corresponding to 3.6 WLM. Now, 1981 the situation has changed considerably. From the average annual exposure of 4.7 WLM in 1970 it is now only 0.7 WLM. Sweden has up to now had only one [uranium] mine and the work there has only been investigative. However, there are plans for a commercial uranium mine in another part of Sweden. The radon problems in these mines are widely different depending on the mineralogy. NON-URANIUM MINES The radiation problems in Swedish mines were not recognised until the late 60's. The first radon and radon daughter measurements were made in some sulphide ore mines in 1967 (1). The radon and radon daughter concentrations were surprisingly high for non-uranium mines. In order to have a complete picture of the radon situation in Swedish mines the National Institute of Radiation Protection (NIRP) decided to make measurements in all, at that time about 60 mines (2). To get results as fast as possible measurements on radon gas seemed most appropriate to start with. Sampling was made by mailing a number of evacuated 4.8 litre conventional propane containers from NIRP to each mine. The containers were then opened at the place of interest. After sampling the containers were sealed and then mailed back to the institute for measurement. The measurements were made in ionization chambers. This method only gave the radon concentration and the radon daughter concentration was estimated by multiplying the radon concentration by an assumed equilibrium factor. The equilibrium factor is defined as the ratio of the total potential alpha energy for the given daughter concentration to the total potential alpha energy of the daughters if they are in equilibrium with the given radon concentration. The results of this first preliminary survey indicated that a great many of the Swedish miners probably had an annual radon daughter exposure of more than 3.6 WLM. As the radiation exposure in non-uranium mines was not regulated in either the Swedish Radiation Protection Act or the Swedish Labour Protection Act work was started on special radon regulations. A lung cancer mortality study was also started. To check the results of the first survey and to get experience and knowledge of radon problems in mines, it was decided that personnel from the NIRP should visit each mine for a detailed investigation of radon and radon daughter concentrations starting with the ones with the highest radon concentrations. The main reasons for these so-called "basic measurements" were: 1. To estimate the doses received by Swedish miners 2. To find the sources of the high radon and radon daughter concentrations 3. To find appropriate counter-measures 4. To determine the most typical equilibrium factor for each mine. Unlike most uranium mines the reason for high radon concentrations in non-uranium mines is seldom the occurrence of highly radioactive minerals. The main sources were found to be waste-rock and radon-rich water. In order to filter and warm up the inlet air, especially in winter time, it was very common at that time to suck the air through broken wasterock. By doing so the air was contaminated with radon from the waste-rock and radon-rich water in it. It is noteworthy that the radium and uranium concentration in the waste-rock is relatively low. The uranium concentration is only of the order of 15 - 20 ppm. The action to prevent this contamination of the inlet air was to change the direction of the ventilation and in the case of radon-rich water entering the mine the action was to prevent the air coming into contact with the water. The first calculation of the radon daughter exposure of Swedish miners was based on radon gas measurements. The radon daughter concentration was estimated by using an assumed equilibrium factor of 0.5. Later when the mines were visited by institute staff it was possible to compare the assumed equilibrium factor with the measured ones. It was found that the factor varied from 0.15 at the air inlet to 1.0 at the air outlet and the average equilibrium factor on workplaces for almost all mines was between 0.4 and 0.6. The result of the exposure calculation in 1970 showed that more than 40 % of the miners had an annual radon daughter exposure of more than 3.6 WLM. The overall average was 4.7 WLM and the maximum annual expo-

Jan 1, 1981

By L. H. Munson, E. H. Carbaugh, D. E. Hadlock, L. F. Munson, R. L. Gilchrist

As a result of the Three Mile Accident and because of evidence indicating radiation protection problems, the U.S Nuclear Regulatory Commission (USNRC) undertook a major effort, with the assistance of the Pacific Northwest Laboratory (PNL), to analyze radiation protection programs at 47 commercially operated nuclear power plants. This effort, the health physics appraisal program (HPAP), using a modified management oversite and risk tree analytical logic methodology (MORT) which consisted of analytical trees with applicable questions for each tree, was subsequently extended to include USNRC licensed uranium mills. In the uranium mill appraisal, a team of four senior radiation safety professionals spent a week at each mill evaluating the total health physics program. Prior to the HPAP, the USNRC inspection efforts were designed to determine if the licensees were fulfilling the requirements of the code of federal regulations and the mills source material license. The HPAP, however, was designed and structured to facilitate an integrated look at the total program. It is also directed into areas for which explicit NRC regulatory requirements may not currently exist. The latitude of the HPAP was designed to allow professional judgement in the evaluation of program adequacy, because merely meeting the explicit regulatory requirements does not necessarily ensure an adequate and effective health physics program. The results of the first eight site visits and the generic health physics problems identified within the uranium milling industry will be identified in this paper.

Jan 1, 1981

By D. Puckett

The feasibility of maintaining equipment location, personnel location and vital statistics in surface and underground mining operations has increased with advances in radio frequency identification (RFID) technology. The paper addresses the use of this technology, relatively new in the mining industry, to track surface equipment in mine pits, loading points, and processing facilities. Specific applications are discussed including a simplified and a complex truck tracking system and an automatic pit ticket system. The paper concludes with a discussion of the future possibilities of RFID technology in mining, such as monitoring biofeedback of personnel (heart and respiration rate, body temperature, exertion level, etc.) repetitious movements to study work habits, and logging air quality via personnel sensors.

Jan 1, 1996

By Michael Wortley

Metso?s Process Technology and Innovation group is a world leader in mineral processing consulting. A significant amount of this consulting work involves process integration and optimization (PIO) studies, which include investigating the effects of drill-and-blast design and implementation on downstream processing. Critical to these studies is the ability to track specific ore into, and through, the plant. To increase the accuracy of this ore tracking, Metso Process Technology and Innovation (PTI) developed a system to track ore using a radio frequency identification (RFID) transponders technology designed to allow tracking of ore from its source through blasting, run-of-mine (ROM) pads, crushers, intermediate stockpiles and, finally, into the concentrator. The system is called SmartTag. Since its commercialization in 2007, SmartTag has been used in the majority of PTI?s consulting projects, and several permanent systems have been installed worldwide.

Jan 1, 2012

By L. G. Stolarczyk

In-mine Continuous Wave (CH) Radio Imaging method (RIM) instrumentation has the capability of measuring EM wave propagation constants in layered formations. The RIM method is based upon the fact that seams of coal, trona, potash, quartzite, gilsonite and oil bearing sands form natural waveguides for low loss transmission of electromagnetic (EM) waves. The waveguide forms whenever the seam is bounded by more conducting claystone, mudstone, shale or in the case of oil/gas traps, by a floor of saline water. Disturbances caused by faults, shear zones, paleochannels, sills and dikes significantly alter the propagation constant. The analytical values of the EM wave propagation constants depend on the physical and electrical parameters of the seam. The values are presented in this paper in a graphical form to assist in the interpretation of RIM tomographic images. This paper compares in-mine geologic mapping obtained during mining to tomographic images of the geologic disturbance zones in a Central Utah coal mine.

Jan 1, 1989

By L. G. Stolarczyk, R. C. Fry

In coal-bearing formations, seams are often bounded by sedimentary layers of mudstone, claystone or shale. When the electrical conductivity of the surrounding sediment layers is greater than the conductivity of the seam, a natural parallel plate waveguide forms in the strata. For frequencies below the AM broadcast band, the waveguide can be used for the transmission of electromagnetic (EM) waves. In a uniform seam, the primary wave travels in the coal layer along paths between a radiating antenna and a distant receiving antenna. The travel distance increases with seam height and the conductivity of the surrounding sediment layers. The distance decreases with increased coal conductivity. In Cretaceous western bituminous coal, the distance may exceed 549 m (1800 ft). Anomalous geologic disturbance zones such as faults, shear zones, paleochannels, sills and dikes significantly alter the values of EM wave propagation constants (attenuation and phase) expected in a uniform seam. In the neighborhood of an anomaly, EM wave energy is scattered (reflected and diffracted). Scattering creates secondary waves in the seam wave guide. A receiving antenna at a remote location in the coal seam can be used to measure the magnitude and phase of the EM wave at the end of the path. The measured data can be processed to determine the average value of the propagation constants along each path. Paths with anomalous propagation constants are used to locate and image geologic disturbance zones. Radio Imaging Method (RIM) instrumentation, survey procedures and data processing (tomography) algorithms have been developed to image geologic structure in advance of mining. The survey is conducted between gate roads of a longwall panel. Data processing constructs contours of constant attenuation rate (phase constant) across the plan view of the panel. In anomalous zones, the contours rapidly change with distance. The shape of the contour lines generates a visual image of the anomaly and suggests the type of anomalous condition to be expected in the coal seam. This paper briefly discusses the depositional environment and the formation of the imperfect waveguide in coal-bearing strata. The linkage between sedimentary geology and EM wave theory establishes an understanding of how the propagation constants depend on the anomalous geologic conditions. A case study compares in-mine geologic mapping with the tomographic image of a longwall panel.

Jan 1, 1991

By Robert F. Randolph, Arnold C. Love

This study describes the positioning strategies used by operators of radio controlled underground mining machines. The observations have implications for task design to insure adequate visibility and task performance. Radio controlled continuous coal mining machines have allowed many mines to increase safety and production by placing human operators away from the hazards of an unsupported mine roof. The operator is no longer confined to an operators component and visibility can be enhanced with proper positioning. Also, the operator is no longer subjected to the shocks and vibrations of the mining machine. The operator's ability to move freely about the worksite requires a careful analysis of several competing safety and production considerations. Thirty-five operators of remotely controlled continuous mining machines were observed using work sampling followed by interviews to determine where the operator was positioned and what he or she was watching. These observations were separated according to the task being performed by the continuous mining machine and summarized as position density plots. The specific task of tramming in reverse through a crosscut is analyzed along with more general summaries of the time miners spend outside of the policy-defined operating positions while performing other production tasks. The operators were: observed to frequently vary from company standard operating procedures (SOP). Many of the variations from company SOPS were based on task demands. Interview responses indicated that portions of the mining task place visibility demands on the operators that are difficult to accommodate within existing procedures. An improved task design process would include these visibility requirements. Also, the operator's vision can be augmented thorough video cameras in future teleoperated mining systems, and the operator can be increasingly isolated from environmental hazards.

Jan 1, 1992

By Gary A. Perry

Cyprus Sierrita produces copper and molybdenum from its Sierrita and Twin Buttes open pit mines south of Tucson, AZ. Both pits were started in the late 1960s and are more than 460 m (1500 ft) deep. Sierrita has used a Caterpillar 992C Remote Controlled Loader since January 1993. The loader was justified to increase safety and profits at Sierrita. It has exceeded all expectations. As of June 1993, the 992C had produced additional profits of more than $1.5 million. Safety and Geotechnical The safety of Cyprus personnel and equipment is always of prime concern. The remote controlled loader removes personnel from the active raveling area. But it requires prudent operation. The remote controlled loader discussed here is always intended to be used in a safe manner under a managed slope. Any increase in slope angle or use of any equipment under a critical slope is taken only after careful analysis of the specific

Jan 1, 1994

By G. A. Perry

Cyprus Sierrita is a major producer of copper and molybdnum from its Sierrita and Twin Buttes open pit mines south of Tucson, Arizona. Both pits were started in the late 60's and are in excess of 1500 feet in depth. Sierrita has utilized a Cat 992C Remote Controlled Loader since January 1993. The loader was justified to increase SAFETY and PROFITS at Sierrita. It has exceeded all expectations. As of June 1993, it had produced additional profits totaling more than $1,500,000.

Jan 1, 1994

By David Hartley

United States Steel Corporation Minntac Mine is located at Mt. Iron, Minnesota, on the Mesabi Iron Range. The taconite pit is two miles long by a mile wide, with a maximum depth of 170 feet. This paper will deal with the radio remote control of locomotives engaged in the railroad haulage of crude ore and waste rock at this property.

Jan 1, 1970

By Jay S. Silhanek, Vernon E. Andrews

[Introduction] Section 122 of the Clean Air Act Amendments of 1977, Public Law 9595, directed the Administrator of the Environmental Protection Agency, to review all relevant information and determine whether emissions of radioactive pollutants into ambient air will cause or contribute to air pollution which may reasonably be anticipated to endanger public health. In August 1979, EPA published a preliminary report on assessments of public health impact resulting from emissions of radionuclides into air from a broad spectrum of major source categories (1). A section of this document presented a theoretical analysis of the radioactive airborne emissions from several non-uranium mines including iron, copper, zinc, clay, limestone, fluorspar, and phosphate. Since 1978 EPA's Las Vegas Laboratory has been gathering field data on actual radionuclide emissions from these mines to support the earlier theoretical analysis. The purpose of this paper is to present the results of those field measurements in comparison with the assumed values for the theoretical analysis. Data were presented in EPA's preliminary report on both gaseous radon-222 and particulate uranium-238 emissions from non-uranium mines. Most of the emissions data were rough estimates based upon the uranium content of the ore. Preliminary data from a few field studies were also used. Although both the theoretical and field studies by EPA were concerned with radon-222 and radioactive particulate emissions, this paper will concentrate only on the radon effluents. Radon from mines seems to have the greatest potential for possible health effects due to radiation. Data on particulate emissions are presented in other technical reports (2-5). [Theoretical Study] The theoretical emission data are presented in Table I. The estimates for the iron, zinc, and clay mines are based upon preliminary measurements taken by the Las Vegas laboratory. The estimates for the other mines were made assuming that 20% of the total radon-222 in the ore was released during the mining process and the radon release rate from the exposed ore surface was a factor of two greater than that resulting from mining. [ ] Dose assessments for radon from these mines were carried out using model facilities located on generic sites (1). The AIRDOS-II computer code (for estimating dispersion of airborne pollutants) with some minor modifications was used to determine working level exposures to a maximally exposed individual and a regional population. A conversion factor for risk/WL-year(O.021 fatal cancers/person-WL-y) was developed primarily from information on uranium miner exposures (6). This computer code and conversion factor were then applied to the assumed emission rate of radon-222 from each type of mine to develop estimates of working levels, lifetime risks and number of fatal cancers. A summary of this data is presented in table II. [ ] The highest estimated number of cancer deaths per year of operation is 0.05 cancer deaths or 1.0 death due to radon during the 24 year life of a phosphorous mine. For comparison, EPA estimates that underground uranium mines would cause .03 cancer deaths per year of operation in a regional population(1). [Field Study] As a followup to the theoretical study, EPA's Las Vegas laboratory began making measurements in 1978 of actual emissions of radon-222 and radioactive particulates from mine vents at several facilities for each of the industries listed in Table I and II. They were intended to verify general information and radon emissions from EPA's theoretical estimates.

Jan 1, 1981

By J. Bigu

Ventilation conditions in working environments are usually studied by anemometry or, in complex cases, b using special tracer gases such as SF6 and 85Kr. in conjunction with chromatographic and radioactivity techniques, respectively. In some working environments, such as underground uranium mines, however, use can be made of the natural radioactivity environment (e.g.. 222rn. 220rn, and their progeny) to investigate mine ventilation conditions of practical interest. Theoretical studies and experimental data in several underground uranium mines and mine locations show that certain thoron progeny to radon progeny concentration ratios are very good indicators of ventilation conditions. Furthermore, the growth and decay of radon progeny and thoron progeny provide valuable information on mine air residence and clearance times. Some specific examples have been analyzed, such as bacterially-assisted uranium leaching operations in a partially enclosed stope, and the effect on the underground environment of turning ventilation fans on and off for a period of time. Air residence times and other variables of interest, determined from the mine radioactivity environment, were compared with more traditional techniques, such as anemometry and tracer gas chromatography. These studies were also extended to a wet non-uranium mine which exhibited relatively high concentrations of radon and its progeny.

Jan 1, 1989

By A. Subbotin

During developing the Ingulska mine at the Mi-churinske uranium deposit in the central part of Ukraine the radioactive rock dumps have been piled. A height of dumps reaches to 15-25m. They occupy a large territory and can be a source of covering with radioactive dust the area around the Ingulska mine. Uranium content exceeds 0,01% in all dump rocks samples while in the dust fraction samples it ranges from 0,01 to 0,06%. Uranium content in road dust at the dump?s foot reaches 0,137%. A new (for Ukraine) method of f-radiography of tree and bush leaves sampled at the territory about 100km2 has been used. It is based on fission of 235U nucleuses due to heat neutron influence in a nuclear reactor and on following study of the Lausan films with tracks drawn by the fractures of these nucleuses. Uranium content of the dif-fusion-disseminated dust type is (0.9-22.2)?10-6% while in the individual particles it can be considered much more because of burned holes in Lavsan above them. The dust content with uranium in Kirovograd reaches to 20-50 part/cm2 while near the dumps it ranges from 100 part/cm2 to 300 part/cm2 in the radius of 1,5-2km from the Ingulska mine.

Jan 1, 2005

By I. Pordea

The materials used for the construction of buildings contain natural radionuclides of the U238 and Th232 series and are ? 50% due to land radioactivity. Another component of natural radioactivity is K40, with ? 40%. The presence of these radiopollutants in the final products (i.e. bricks, concrete) due to body irradiation is by two pathways: external irradiation and internal irradiation. External irradiation is due to gamma radiations emitted by Pb214 (RaB) + Bi214 (RaC) from the U238 series, by Ra228 (Mezothoriu I) + Ac228 (Mezothoriu II) + Tl208 (ThC??) from the Th232 series and by the K40 radionuclide. Internal irradiation is due to inhalation of radon (Rn222) and Rn220 (Tn) plus short life descendents (Po, Pb, Bi), radionuclides which are present in concrete. A fraction from radon present in concrete enters into a house leading to internal irradiation by inhalation. In Romania, the maximum concentration of radon allowed for new buildings is 200 Bq/m3.

Jan 1, 2008

By Raymond E. Kary, John W. Mcklveen

The four unit Cholla coal fired power station at Joseph City, Arizona, consumes coal from the McKinley mine located in western New Mexico. Since coals may contain relatively high uranium or thorium concentrations and may release quantities of detrimental progeny of these elements to the environs, there is concern that releases may pose an adverse environmental impact or even a health hazard to the workers. Thus, an effort was made to quantify the radionuclide content of the coal and compare the results with radionuclide concentrations already present in the vicinity of the plant. Additionally an attempt was made to assess any potential for significant enhancement of the levels of radioactivity in the environment or to plant personnel. Background gamma radiation measurements at and near the plant ranged from 8 to 12 [µ]R/hr (70 to 105 mR/yr) with a few localized anomolies measuring to 18 [u]R/hr (160 mR/yr). Levels on top of the coal storage piles decreased to ~ 6.5 [u]R/hr (60 mR/yr). Apparently the direct radiation emitted from the coal is less than the background levels in the vicinity of the plant. Measurements performed on top of several coal seams at the mine confirmed low radiation levels emanating from coal, but readings more than doubled when the overburden was monitored. Laboratory gamma spectrometry confirmed the lower amounts of natural radioactivity in the coal when compared against soil and water samples obtained in the vicinity of the plant and the overburden at the mine. In an effort to see if there is biological enhancement, animal feces was sampled. The radiation variations were found to be influenced primarily by naturally occurring potassium-40 which varied from ~ 1 to 18 pCi/gm rather than fluctuations in the uranium and thorium series. The potassium-40 concentrated in the ash were similar to the concentrations in the environs around the disposal ponds while Radium-226 concentrated in the fly ash was ~ 3 times that found in the immediate surroundings. Radon-222 gas concentrations in buildings at or near the plant ranged from 0.5 to 1.8 pCi/l and were generally lower than indoor concentrations measured in the Phoenix area. The burning of coal at the Cholla station does not appear to increase ambient levels of radioactivity found in the surrounding environs or to the workers. However, the use of byproduct fly ash for construction purposes may need to be examined.

Jan 1, 1981