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M. Case - S. M. Stoller Corporation
M. Verdoorn - Bechtel/BWXTIdaho, LLC
R. Wilhelmsen - Bechtel/BWXTIdaho, LLC
The Idaho National Engineering and Environmental Laboratory (INEEL) environmental surveillance programs (conducted by the Management and Operating [M&O] contractor and the Environmental Surveillance, Education and Research Program [ESER] contractor) emphasize measurement of airborne radionuclides because air transport is considered the major potential pathway from INEEL releases to receptors. The M&O contractor monitors airborne effluents at individual INEEL facilities and ambient air outside the facilities to comply with appropriate regulations and U.S. Department of Energy (DOE) orders. The ESER contractor samples ambient air at locations within, around, and distant from the INEEL.
An estimated total of 8,816 curies of radioactivity, primarily in the form of short-lived noble gas isotopes, was released as airborne effluents in 2004. Samples of airborne particulates, atmospheric moisture, and precipitation were analyzed for gross alpha and gross beta activity, as well as for specific radionuclides, primarily tritium, strontium-90, iodine-131, cesium-137, plutonium-239/240, and americium-241. Results do not indicate any link between radionuclides released from the INEEL and environmental concentrations measured offsite. All concentrations were well below regulatory standards and within historical measurements.
Nonradiological pollutants, including particulates, were monitored at select locations around the INEEL. All results were well below regulatory standards.
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This chapter presents the results of radiological and nonradiological analyses performed on airborne effluents and ambient air samples taken at locations both on the Idaho National Engineering and Environmental Laboratory (INEEL) and offsite. Results from sampling conducted by the Management and Operating (M&O) contractor and the Environmental Surveillance, Education and Research (ESER) Program contractor are presented. Results are compared to the U.S. Environmental Protection Agency (EPA) health-based levels established in environmental statutes and/or the U.S. Department of Energy (DOE) Derived Concentration Guides (DCGs) for inhalation of air (Appendix A).
The facilities operating on the INEEL release both radioactive and nonradioactive constituents into the air. Various pathway vectors (such as air, soil, plants, animals, and groundwater) may transport radioactive and nonradioactive materials from the INEEL to nearby populations. These transport pathways have been ranked in terms of relative importance (EG&G 1993). The results of the ranking analysis indicate that air is the most important transport pathway. The INEEL environmental surveillance programs, conducted by the M&O contractor and the ESER contractor, emphasize measurement of airborne radionuclides because air has the potential to transport a large amount of activity to a receptor in a relatively short period and can result in direct exposure to offsite receptors. Table 4-1 summarizes the air monitoring activities conducted by each organization at the INEEL.
The M&O contractor monitors airborne effluents at individual INEEL facilities and ambient air outside the facilities to comply with applicable statutory requirements and DOE orders. The M&O contractor collected approximately 2,300 air samples (primarily on the INEEL) for analyses in 2004.
The ESER contractor collects samples from an approximately 23,309 km2 (9000 mi2) area of southeastern Idaho and Jackson, Wyoming, at locations on, around, and distant to the INEEL. The ESER Program collected approximately 2,200 air samples, primarily off the INEEL, for analyses in 2004. Section 4.2 summarizes results of air monitoring by the M&O and ESER contractors. Section 4.3 discusses air sampling performed by the M&O contractor in support of waste management activities.
The INEEL Oversight Program operates a series of air monitoring stations, often collected at locations used by the M&O and ESER contractors. The results are presented in annual reports prepared by the Oversight Program and are not reported in Chapter 4.
Unless specified otherwise, the radiological results discussed in the following sections are those greater than three times the associated analytical uncertainty (see Appendix B for information on statistical methods). Each individual result is reported in tables as the measurement plus or minus one sigma (± 1s) analytical uncertainty for that radiological analysis.
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Airborne effluents are measured at or estimated for regulated facilities as required under the Idaho State Implementation Plan (http://yosemite.epa.gov/r10/AIRPAGE.NSF/SIPs and http://www2.state.id.us/adm/adminrules/rules/idapa58/0101.pdf ). Monitoring or estimating effluent data is the responsibility of programs associated with the operation of each INEEL facility and not the environmental surveillance programs.
Environmental surveillance of air pathways is the responsibility of the M&O contractor and the ESER contractor. Figure 4-1 shows the surveillance air monitoring locations for the INEEL environmental surveillance programs.
The INEEL environmental surveillance program contractors collect filters from a network of low-volume air monitors weekly. Air flows (at an average of about 57 L/min [2 cfm]) through a set of filters consisting of a 5 cm (2 in.), 1.2 µm pore membrane filter followed by a charcoal cartridge. The membrane filters are analyzed weekly for gross alpha and gross beta activity. Filters are then composited quarterly by location for analysis of gamma-emitting radionuclides using gamma spectrometry and for specific alpha- and beta-emitting radionuclides using radiochemical techniques. In addition to the membrane filter samples, charcoal cartridges are collected and analyzed weekly for iodine-131 (131I), using gamma spectrometry.
There is no requirement to monitor the dust burden at the INEEL, but the M&O and the ESER contractors monitor this to provide comparison information for other monitoring programs and to the DOE-Idaho Operations Office (DOE-ID). The suspended particulate dust burden is monitored with the same low-volume filters used to collect the radioactive particulate samples by weighing the filters before and after their use in the field.
The ESER contractor also monitors particles with an aerodynamic diameter less
than or equal to 10 microns (PM10), the respirable particle size, for
comparison to EPA air quality standards.
Nitrogen dioxide was measured in past years to meet permit requirements for the New Waste Calcining Facility (NWCF). A permit modification was granted to the INEEL requiring that monitoring be conducted only during operation of the NWCF, which is currently shut down and did not operate in 2004. Therefore, the M&O contractor no longer monitors nitrogen dioxide.
Tritium in water vapor in the atmosphere is monitored by the M&O and ESER contractors using samplers located at two onsite locations (Experimental Field Station [EFS] and Van Buren Boulevard) and five offsite locations (Atomic City, Blackfoot, Craters of the Moon, Idaho Falls, and Rexburg). Air passes through a column of adsorbent material (molecular sieve) that adsorbs water vapor in the air. Columns are changed when the material absorbs sufficient moisture to obtain a sample. Water is extracted from the material by distillation and collected. Tritium concentrations are then determined by liquid scintillation counting of the water extracted from the columns.
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During 2004, an estimated 8,816 Ci of radioactivity was released to the atmosphere from all INEEL sources. The National Emissions Standards for Hazardous Air Pollutants (NESHAP) Calendar Year 2004 INL Report for Radionuclides (DOE-ID/2005) describes three categories of airborne emissions. The first category includes sources that require continuous monitoring under the NESHAP regulation. The second category consists of releases from other point sources. The final category is nonpoint, or diffuse, sources. These include radioactive waste ponds and contaminated soil areas. All three categories are represented in Table 4-2 of this report. Only radionuclides that are potentially significant contributors to the INEEL dose (i.e., >1E-05 mrem) are listed in the NESHAP report. Table 4-2 only includes the screened NESHAP radionuclides with releases greater than 1 pCi/yr.
The largest facility contributions to the total emissions came from the Idaho Nuclear Technology and Engineering Center (INTEC) at more than 58 percent, Test Reactor Area (TRA) at approximately 15 percent, and Argonne National Laboratory-West (ANL-W) at approximately 27 percent (Table 4-2). Approximately 86 percent of the radioactive effluent was in the form of noble gases (argon, krypton, and xenon). Most of the remaining effluent (14 percent) was tritium.
Low-Volume Charcoal Cartridges
Both the ESER and M&O contractors collected charcoal cartridges weekly and analyzed them for gamma-emitting radionuclides. Charcoal cartridges are primarily used to collect gaseous radioiodines. If traces of any human-made radionuclide were detected, the filters were individually analyzed. During 2004, the ESER contractor analyzed 936 cartridges, looking specifically for 131I. No 131I was detected in any of the individual ESER samples. No iodine was detected in samples collected by the M&O contractor.
Low-Volume Gross Alpha
Particulates filtered from the air were sampled from 29 locations weekly as part of the INEEL environmental surveillance programs (see Figure 4-1). All were analyzed for gross alpha activity and gross beta activity. Gross alpha concentrations found in ESER contractor samples, both on and offsite, tended to be higher than those found in M&O contractor samples at common locations. Reasons for differences in concentrations measured at the same locations are likely caused by differences in laboratory analytical techniques and instrumentation, as different analytical laboratories were used. Both sets of data indicated gross alpha concentrations at onsite locations were generally equal to or lower than at boundary and offsite locations.
Weekly gross alpha concentrations in ESER contractor samples that exceeded their 3 sigma uncertainty ranged from a minimum of (0.77 ± 0.25) x 10-15 µCi/mL at the Mud Lake Q/A-2 station during the week ending February 4, 2004, to a maximum of (6.16 ± 0.71) x 10-15 µCi/mL during the week ending January 21, 2004, at Idaho Falls. Concentrations measured by the M&O contractor that exceeded their 3 sigma uncertainty ranged from a low of (0.57 ± 0.12) x 10-15 µCi/mL collected at the Auxiliary Reactor Area (ARA) on January 14, 2004, to a high of (12.9 ± 0.14) x 10-15 µCi/mL collected at the U.S. 20 Rest Area on January 21, 2004.
Figure 4-2 displays the median weekly gross alpha concentrations for the ESER
and M&O contractors at INEEL, boundary, and distant station groups. Each weekly
median was computed using all measurements, including those less than their
associated 3 sigma uncertainties. These data are typical of the annual natural
fluctuation pattern for gross alpha concentrations in air. According to Figure 4-2, the highest median weekly concentration of gross alpha was measured by the
M&O contractor for the distant group in the fourth quarter of 2004. The maximum
median weekly gross alpha concentration was 4.7 x 10-15 µCi/mL and is below the
DCG for the most restrictive alpha-emitting radionuclide in air [americium-241
(241Am)] of 20 x 10-15 µCi/mL.
Annual median gross alpha concentrations calculated by the ESER contractor ranged from 1.09 x 10-15 µCi/mL at Blue Dome to 1.78 x 10-15 µCi/mL at Mud Lake (Table 4-3). Confidence intervals are not calculated for annual medians. Annual median gross alpha concentrations calculated by the M&O contractor ranged from 1.19 x 10-15 µCi/mL at Craters of the Moon to 1.92 x 10-15 µCi/mL at Rexburg.
In general, gross alpha concentrations were typical of those measured previously and well within the range of measurements observed historically from 1995 through 2004 (Figure 4-3).
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Low-Volume Gross Beta
Gross beta concentrations in ESER contractor samples were fairly consistent with those found in M&O contractor samples.
Weekly gross beta concentrations in ESER contractor samples that exceeded their 3 sigma uncertainty ranged from a low of (0.29 ± 0.05) x 10-14 µCi/mL on March 10, 2004, at Idaho Falls to a high of (16.5 ± 0.29) x 10-14 µCi/mL at Mud Lake on January 21, 2004. Concentrations measured above 3 sigma by the M&O contractor ranged from a low of (0.22 ± 0.05) x 10-14 µCi/mL at ANL-W in March 10, 2004, to a high of (50.40 ± 3.34) x 10-14 µCi/mL at the EFS in January 2004.
Figure 4-4 displays the median weekly gross beta concentrations for the ESER and M&O contractors at INEEL, boundary, and distant station groups. These data are typical of the annual natural fluctuation pattern for gross beta concentrations in air, with higher values generally occurring at the beginning and end of the calendar year during winter inversion conditions. The highest median weekly concentration of gross beta activity was detected in the first quarter of 2004. Each median value was calculated using all measurements, including those less than the associated 3 sigma uncertainties. The maximum weekly median gross beta concentration was 10.0 x 10-14 µCi/mL and is significantly below the DCG of 300 x 10-14 µCi/mL for the most restrictive beta-emitting radionuclide in air (radium-228 [228Ra]).
Annual median gross beta concentrations are shown in Table 4-4. ESER contractor annual median gross beta concentrations ranged from 2.27 x 10-14 µCi/mL at Dubois to 2.57 x 10-14 µCi/mL at the EFS. M&O contractor data indicated an annual median range of 2.00 x 10-14 µCi/mL at Craters of the Moon to 2.42 x 10-14 µCi/mL at Rexburg. In general, the levels of airborne radioactivity for the three groups (INEEL, boundary, and distant locations) tracked each other closely throughout the year. This indicates that the pattern of fluctuations occurred over the entire sampling network, is representative of natural conditions, and is not caused by a localized source such as a facility or activity at the INEEL.
In addition, all results greater than 3 sigma reported by the ESER contractor are well within measurements taken within the last ten years (Figure 4-5). The maximum concentration detected in 2004 is within this range of results.
Gross beta concentrations can vary widely from location to location as a result of a variety of factors, such as local soil type and meteorological conditions. When statistical differences are found in gross beta activity, these and other factors are examined to assist with identifying the cause for the differences, including a possible INEEL release.
Statistical comparisons were made using the gross beta radioactivity data collected from the onsite, boundary, and distant locations (see Appendix B for a description of statistical methods). Figure 4-6 is a graphical comparison of all gross beta concentrations measured during 2004 by the ESER contractor. The results are grouped by location (that is, INEEL, boundary and distant stations). Visually, there appeared to be no difference between locations. The figure also shows that the largest measurement was well below the DCG for the most restrictive beta-emitting radionuclide (228Ra) in air of 300 x 10-14 µCi/mL. If the INEEL were a significant source of offsite contamination, concentrations of contaminants would be statistically greater at boundary locations than at distant locations. There were no statistical differences between annual concentrations collected from INEEL, boundary, and distant locations in 2004.
There were a few statistical differences between weekly boundary and distant data sets collected by the ESER contractor during the 52 weeks of 2004. Concentrations collected during one week each in February, August, and September were greater for the boundary group than for the distant group. The differences observed in February appear to be related to the influence of inversion conditions. The differences observed in the August and September can be attributed to natural variation in the data. None of the weekly concentrations were greater at the distant locations when compared to the boundary locations.
The M&O contractor data were grouped into INEEL and distant data sets. There were no statistical differences between data obtained from INEEL and distant locations.
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Specific Radionuclides in Air
Human-made radionuclides were observed above 3 sigma values in some ESER contractor and M&O contractor quarterly composite samples (Table 4-5 and Table 4-6).
Since mid-1995, the ESER contractor has detected 241Am in some air samples, although there has been no discernable pattern with respect to time or location. Americium-241 was again detected in four 2004 quarterly composite samples. A frequency plot of 241Am concentrations detected in ESER contractor samples over the past eight years is shown in Figure 4-7. All results detected above the 3 sigma level during 2004 were within the range measured historically and are well below the 241Am DCG of 20,000 x 10-18 µCi/mL.
Plutonium-238 (238Pu) was not detected in any ESER sample in 2004. Plutonium-239/240 (239/240Pu) was detected in two composite samples, one at Rexburg during the first quarter and one at Howe during the third quarter. Plutonium is a residual product of nuclear fission. All valid 239/240Pu levels were significantly below the 239/240Pu DCG of 20,000 x 10-18 µCi/mL. The concentrations measured in ESER samples are consistent with worldwide levels related to atmospheric nuclear weapons testing and are well within past measurements (Figure 4-8).
Strontium-90 (90Sr) was detected in three ESER samples. The values measured are much below the DCG of 9,000,000 × 10-18 µCi/mL. The results are well within historical measurements (Figure 4-9).
Cesium-137 (137Cs) was not detected in any ESER sample.
Isotopes of uranium (234U, 235U or 238U) were detected in numerous M&O contractor quarterly composites at levels which indicate their origin as naturally occurring.
The M&O contractor reported no detections of 241Am or 239,240Pu.
Stontium-90 was detected in seven quarterly composites collected by the M&O contractor during 2004. The maximum result (250.0 ± 70.0) x 10-18 µCi/mL , is well below the DCG for 90Sr and within historical measurements
Cesium-137 was detected in one M&O contractor sample. The measurement is within those made by the EPA at Idaho Falls from 1984 through 2004, as reported on the Environmental Radiation Ambient Monitoring System website (http://www.epa.gov/enviro/html/erams/).
During 2004, the ESER contractor collected 62 atmospheric moisture samples from four locations (Atomic City, Blackfoot, Idaho Falls, and Rexburg) using silica gel and molecular sieve. Table 4-7 presents the range of values for each station by quarter.
Tritium was detected in 14 of the samples. Samples that exceeded the respective 3 sigma values ranged from a low at Atomic City (4.4 ± 1.3) × 10-14 µCi/mL collected on November 1, 2004, to a high (77.5 ± 18.0) × 10-14 µCi/mL at Rexburg collected on October 12, 2004.
These detected radioactive concentrations were similar at distant and boundary locations. This similarity suggests that the detections probably represent tritium from natural production in the atmosphere by cosmic ray bombardment, residual weapons testing fallout, and possible analytical variations, rather than tritium from INEEL operations. The highest observed tritium concentration (from the fourth quarter at Rexburg) is more than five orders of magnitude below the DCG for tritium in air (as hydrogen tritium oxygen [HTO]) of 1 × 10-7 µCi/mL.
The M&O contractor collected atmospheric moisture samples at the EFS and at
Van Buren Boulevard on the INEEL and at Idaho Falls and Craters of the Moon off
the INEEL. They collect from one to three samples at each location each quarter.
One sample indicated an activity greater than its 3 sigma level. The sample was
taken at EFS in the fourth quarter with a value of
(40.9 ± 13.6) × 10-14 µCi/mL. This value is consistent with ESER contractor results and is significantly less than the DCG for tritium in air.
The ESER contractor collects precipitation samples weekly at the EFS and monthly at the CFA and offsite in Idaho Falls. A total of 26 precipitation samples were collected during 2004 from the three sites. Tritium concentrations were measured above the 3 sigma uncertainty level in eight samples and results ranged from (79.9 ± 25.3) to (200.0 ± 28.1) pCi/L. Table 4-8 shows the maximum concentration by quarter for each location. The highest radioactivity was from a sample collected at CFA during the fourth quarter and is far below the DCG level for tritium in water of
2 × 106 pCi/L. The concentrations are well within the normal range observed historically at the INEEL. The maximum concentration measured since 1998 was (553 ± 78) pCi/L, measured at the EFS in 2000. The results are also well within measurements made by the EPA in Region 10 (Alaska, Idaho, Oregon, and Washington) for the past ten years (http://www.epa.gov/enviro/html/erams/ ).
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In 2004, both the ESER and M&O contractors measured concentrations of suspended particulates using filters collected from the low-volume air samplers. The filters are 99 percent efficient for collection of particles greater than 0.3 µm in diameter. Unlike the fine particulate samplers discussed in the next section, these samplers do not selectively filter out particles of a certain size range, so they collect the total particulate load greater than 0.3 µm in diameter.
Particulate concentrations from ESER contractor samples ranged from 0.08 µg/m3 at Craters of the Moon to 19.7 µg/m3 at Blackfoot. In general, particulate concentrations were higher at distant locations than at the INEEL stations. This is mostly caused by agricultural activities in offsite areas.
The total suspended particulate concentrations measured by the M&O contractor ranged from 0.0 µg/m3 at CFA, Craters of the Moon, and RWMC, to 161.0 µg/m3 at EFS. Sample particulate concentrations were generally higher at distant locations than at the INEEL stations.
The EPA's air quality standard is based on concentrations of "particles with an aerodynamic diameter less than or equal to 10 microns" (PM10) (40 CFR Part 50.6). Particles of this size can reach the lungs and are considered to be responsible for most of the adverse health effects associated with airborne particulate pollution. The air quality standards for PM10 are an annual average of 50 µg/m3, with a maximum 24-hour concentration of 150 µg/m3.
The ESER contractor collected 61 valid 24-hour samples at Rexburg from January through December 2004. A valid sample is one that has run for the proper length of time (24 hours continuously) and that has a beginning weight less than the ending weight (does not yield a negative weight). Concentrations of PM10 particulates collected at Rexburg ranged from 1.9 to 47.6 µg/m3. At the Blackfoot CMS, 61 valid samples were collected from January through December. Concentrations ranged from 1.5 to 39.3 µg/m3. At Atomic City, 61 valid samples were collected from January through December. Concentrations ranged from 0.0 to 84.5 µg/m3. All measurements were less than the EPA standard for mean annual concentration.
Emissions from the Experimental Breeder Reactor II auxiliary boilers do not require continuous monitoring because they are below the state of Idaho's 250 million Btu/hr emission limit. Monitoring at this facility occurs monthly with a portable stack emission monitor as an efficiency check and to ensure nitrogen dioxide and sulfur dioxide emissions are below state-imposed standards.
Interagency Monitoring of Protected Visual Environments (IMPROVE) samplers began continuous operation at Craters of the Moon and CFA during the spring of 1992. The EPA removed the CFA sampler from the national network in May 2000, when the location was determined to be no longer necessary. The most recent data available for the station at Craters of the Moon are through November 2003.
The IMPROVE samplers measure several elements, including aluminum, silicon, calcium, titanium, and iron. These elements are derived primarily from soils and show a seasonal variation, with lower values during the winter when the ground is often covered by snow. Potassium is also measured and may be derived from soils, but it is also a component of smoke.
Other elements are considered tracers of various industrial and urban activities. Lead and bromine, for example, result from automobile emissions. Annual concentrations of lead at IMPROVE sites in the mid-Atlantic states are commonly in the range of 2 to 6 ng/m3, or up to ten times higher than at Craters of the Moon. Selenium, in the 0.1 ng/m3 range at Craters of the Moon, is a tracer of emissions from coal-fired plants.
Fine particles with a diameter less than 2.5 microns (PM2.5) are the size fraction most commonly associated with visibility impairment. At Craters of the Moon, PM2.5 has ranged over the period of sampler operation from 409 to 25,103 ng/m3, with a mean of 3443 ng/m3.
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Gross Alpha and Gross Beta Air Monitoring Results
Gross alpha and gross beta activity were determined on all waste management samples collected by the Management and Operating contractor in 2004. Samples were obtained from suspended particle (SP) monitors.
Suspended particle monitors had gross alpha measurements that exceeded their 3 sigma uncertainty ranging from a high of (1.40 ± 0.51) × 10-15 µCi/mL in the first half of January at location SDA-6.3 to a low of (1.50 ± 0.50) × 10-16 µCi/mL in the first half of October at location HOWE-400.3. The annual mean for gross alpha was 1.23 × 10-15 µCi/mL. SP gross beta levels ranged from a high of (3.09 ± 0.09) × 10-13 µCi/mL in the first half of January at SDA-6.3 to a low of (2.10 ± 0.13) × 10-15 µCi/mL at HOWE-400.3 in the second half of April. The gross beta annual mean was 3.71 × 10-14 µCi/mL.
Anthropogenic gamma-emitting radionuclides were detected in 2004 that exceeded the three-sigma uncertainty. In April, cobalt-57 (8.50 ± 0.88) × 10-15 mCi/mL, cobalt-60
(8.35 ± 0.84) × 10-15 µCi/mL, and manganese-54 (4.52 ± 0.89) × 10-15 µCi/mL were detected at location HOWE-400.3. These isotopes are activated corrosion products generated from operation of nuclear reactors. Analysis of site surveillance samples from the same time period showed no contamination from these nuclides, which indicates no unmonitored release. Due to the short half-lives of cobalt-57 (about 272 days) and manganese-54 (about 312 days), they are unlikely to come from buried waste. Subsequent samples at this location indicated no recurring contamination. Antimony 124 was detected at location SDA-6.3 (1.31 ± 0.35) × 10-15 µCi/mL at the Subsurface Disposal Area. This nuclide has a short half-life (about 60 days), and therefore it is doubtful that it is from current waste retrieval operations at the Subsurface Disposal Area, and the result is suspect. All gamma detections are significantly below their respective Derived Concentration Guides.
Radiochemical analysis detections for alpha- and beta-emitting radionuclides of greater than the 3 sigma uncertainty level are listed in Table 4-9.
During the first quarter, americium-241 was detected on several samples. These results were rejected because americium was detected in the blank sample. Contamination at the analytical laboratory is suspected.
Plutonium-239/240 was detected at location SDA-4.2 in the first quarter of 2004 and at location SDA-4.3 in the second quarter, and strontium-90 was detected at SDA 4.2 during the second quarter and at SDA-4.3 in the fourth quarter. These two monitors are collocated, and there were no detections for the same sample period at the collocated monitor. However, a sampler collecting a single particle with activity at this level is possible, and these results are considered valid without regard to field duplicate precision criteria.
Uranium-234, -235, and -238 were detected in numerous samples at levels that indicate their origin as naturally occurring radioisotopes.
Results at these levels are well below the respective DCGs and consistent with previous years. The most probable cause of detections at the Subsurface Disposal Area is resuspension of contaminated soil. Loss of confinement integrity would give substantially higher results. No trends were detected based on analytical results from calendar year 2004.
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40 Code of Federal Regulations 50.6, "National Primary and Secondary Ambient Air Quality Standards for Particulate Matter," Code of Federal Regulations, Office of the Federal Register.
EG&G Idaho, Inc., 1993, New Production Reactor Exposure Pathways at the INEL, EGG-NPR-8957.
U.S. Department of Energy-Idaho Operations Office (DOE-ID), 2005, National Emissions Standards for Hazardous Air Pollutants (NESHAPs) - Calendar Year 2004 INL Report for Radionuclides, DOE/NE-ID-10890(05).
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