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M. Case - S. M. Stoller Corporation
M. Verdoorn - Battelle Energy Alliance
R. Wilhelmsen - CH2M-WG Idaho
The Idaho National Laboratory (INL) onsite environmental surveillance programs are the primary responsibility of the INL contractor (Battelle Energy Alliance [BEA]) and the Idaho Cleanup Project (ICP) contractor (CH2M-WG Idaho [CWI]). The Environmental Surveillance, Education and Research (ESER) contractor who, during 2005, was a team led by the S. M. Stoller Corporation, is primarily responsible for the offsite environmental monitoring program. These programs emphasize measurement of airborne radionuclides because air transport is considered the major potential pathway from INL Site releases to receptors. The INL and ICP contractors monitor airborne effluents at individual INL Site 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 INL Site.
An estimated total of 6614 curies of radioactivity, primarily in the form of short-lived noble gas isotopes, was released as airborne effluents in 2005. 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 INL Site and environmental concentrations measured offsite. All concentrations were well below regulatory standards and most were within historical measurements.
Nonradiological pollutants, including particulates, were monitored at select locations around the INL Site. All results were well below regulatory standards.
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 Laboratory (INL) Site and offsite. Results from sampling conducted by the INL contractor, the Idaho Cleanup Project (ICP) contractor and the Environmental Surveillance, Education and Research Program (ESER) 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 INL Site 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 INL Site 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 INL Site environmental surveillance programs, conducted by the INL contractor, the ICP 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 t he air monitoring activities conducted by each organization at the INL Site.
The INL contractor monitors airborne effluents at individual INL facilities and ambient air outside the facilities to comply with applicable statutory requirements and DOE orders. The INL contractor collected approximately 2400 air samples (primarily on the INL Site) for analyses in 2005.
The ESER contractor collects samples from approximately 23,309 km2 (9000 mi2) area of southeastern Idaho and Jackson, Wyoming at locations on, around, and distant to the INL Site. The ESER Program collected approximately 2300 air samples, primarily off the INL Site, for analyses in 2005. Section 4.2 summarizes results of air monitoring by the INL and ESER contractors. Section 4.3 discusses air sampling performed by the ICP contractor in support of waste management activities.
The INL Oversight Program operates a series of air monitoring stations, often collected at locations used by the INL and ESER contractors. These 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 analytical (± 1s) 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 (SIP). Monitoring or estimating effluent data is the responsibility of programs associated with the operation of each INL Site facility and not the environmental surveillance programs.
Environmental surveillance of air pathways is the responsibility of the INL, ICP,
and ESER contractors. Figure 4-1 shows the surveillance air monitoring locations
for the INL Site environmental surveillance programs.
For onsite and offsite air surveillance monitoring, filters are collected from a network of low-volume air monitors weekly. Air flows (at an average of about 57 L/minute [2 ft3/minute]) 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 INL Site, but the INL
and ESER contractors monitor this to provide comparison information for other
monitoring programs. 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) to compare to EPA air quality standards.
Tritium in water vapor in the atmosphere is monitored by the INL 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.
During 2005, an estimated 6,614 Ci of radioactivity were released to the
atmosphere from all INL Site sources. The National Emissions Standards for
Hazardous Air Pollutants (NESHAP) Calendar Year 2005 INL Report for
Radionuclides (DOE-ID 2006) 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 2 (Sections A, B, C, and D) of this report. Only radionuclides that are potentially
significant contributors to the INL Site dose (i.e., >1E-05 mrem) are listed in
the NESHAPs report. Table 2 (Sections A, B, C, and D) only includes the screened NESHAPs radionuclides
with releases greater than 1 pCi/year.
The largest facility contributions to the total emissions came from the Idaho Nuclear Technology and Engineering Center (INTEC) at more than 65 percent, Reactor Technology Complex at approximately 13.5 percent, and Materials and Fuels Complex at approximately 21 percent (Table 2 -Sections A, B, C, and D). Approximately 88 percent of the radioactive effluent was in the form of noble gases (argon, krypton, and xenon). Most of the remaining effluent (12 percent) was tritium.
Both the ESER and INL 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 2005, the ESER contractor analyzed 1171 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 INL contractor.
Particulates filtered from the air were sampled from 29 locations weekly as part of the INL Site environmental surveillance programs (see Figure 4-1). All were analyzed for gross alpha activity and gross beta activity. Gross alpha concentrations found in INL contractor samples, both on and offsite, tended to be higher than those found in ESER 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 locations.
Weekly gross alpha concentrations detected in ESER contractor samples (i.e., measurements which exceeded their associated 3 sigma uncertainties) ranged from a minimum of 0.93 x 10-15 µCi/mL at the Howe Q/A-2 station during the week ending October 12, 2005, to a maximum of 4.53 x 10-15 µCi/mL during the week ending December 14, 2005, at Idaho Falls. Concentrations measured by the INL contractor that exceeded their 3 sigma uncertainty ranged from a low of 0.54 x 10-15 µCi/mL collected at Gate 4 on the INL Site on December 7, 2005, to a high of 7.37 x 10-15 µCi/mL collected at Blackfoot on November 2, 2005.
Figure 4-2 displays the median weekly gross alpha concentrations for the ESER and INL contractors at INL Site, boundary, and distant station groups. It also shows historical medians and ranges measured by the ESER contractor from 1999- 2004. 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 ESER contractor for the INL group in the fourth quarter of 2005. The maximum median weekly gross alpha concentration was 1.4 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 0.85 x 10-15 µCi/mL at Blue Dome to 1.72 x 10-15 μCi/mL at Idaho Falls (Table 4-3). Confidence intervals are not calculated for annual medians. Annual median gross alpha concentrations calculated by the INL contractor ranged from 1.31 x 10-15 μCi/mL at Craters of the Moon to 2.05 x 10-15 μCi/mL at Rexburg.
In general, gross alpha concentrations were typical of those detected previously and well within the range of measurements observed historically for the ten-year period from 1996 through 2005 (Figure 4-3).
Gross beta concentrations in ESER contractor samples were fairly consistent with those found in INL contractor samples.
Weekly gross beta concentrations detected in ESER contractor samples ranged from a low of 0.71 x 10-14 µCi/mL on December 7, 2005, at Blackfoot to a high of 7.97 x 10-14 µCi/mL at Mud Lake on December 14, 2005. Concentrations measured above 3 sigma by the INL contractor ranged from a low of 0.82 x 10-14 µCi/mL at Rexburg on March 30, 2005, to a high of 7.75 x 10-14 µCi/mL at Test Area North on December 14, 2005.
Figure 4-4 displays the median weekly gross beta concentrations for the ESER and INL contractors at INL Site, boundary, and distant station groups. as well as historical median and range data measured by the ESER contractor from 1999-2004. 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 fourth quarter of 2005 by the INL contractor on the INL Site. Each median value was calculated using all measurements, including those less than their associated 3 sigma uncertainties. The maximum weekly median gross beta concentration was 6.3 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 2.13 x 10-14 µCi/mL at Craters of the Moon to 2.65 x 10-14 µCi/mL at the EFS. INL contractor data indicated an annual median range of 2.27 x 10-14 µCi/mL at Van Buren to 2.79 x 10-14 µCi/mL at INTEC. In general, the levels of airborne radioactivity for the three groups (INL Site, 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 INL Site.
In addition, all results greater than 3 sigma reported by the ESER contractor are well within valid measurements taken within the last ten years (Figure 4-5) (this figure does not include recounts). The maximum concentration measured in 2005 is within this range of results.
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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 INL Site 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 2005 by the ESER contractor. The results are grouped by location (that is, INL Site, 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 INL Site 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 INL Site, boundary, and distant locations in 2005.
There were a few statistical differences between weekly boundary and distant data sets collected by the ESER contractor during the 52 weeks of 2005. 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 August and September can be attributed to expected statistical variation in the data. None of the weekly concentrations were greater at the distant locations when compared to the boundary locations.
INL contractor onsite and distant data sets were compared and there were no statistical differences between data obtained from INL Site and distant locations.
Human-made radionuclides were observed above 3 sigma values in some ESER contractor and INL 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 the third quarter 2005 quarterly composite sample collected onsite at Van Buren Gate. A frequency plot of 241Am concentrations detected in ESER contractor samples over the past nine years is shown in Figure 4-7. The result detected in 2005, 8.52 × 10-17, is above the range measured historically, but is only 0.43 percent of the 241Am DCG of 20,000 x 10-18 µCi/mL. The radionuclide concentration on the filter is considered an anomalous result. Windblown soil from the nearby Radioactive Waste Management Complex (RWMC) is an unlikely source as soil in this area also contains plutonium radionuclides in fairly constant ratios with 241Am. In addition, there was not enough particulate loading on the filter to indicate a windblown soil source. Finally, laboratory contamination is not indicated by either the field blank or laboratory blank.
Plutonium isotopes were not detected in any ESER sample in 2005. Valid 239/240Pu levels concentrations measured historically 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. Two of the results were outside historical measurements (Figure 4-9). However, the values measured are much below the DCG of 9,000,000 x 10-18 µCi/mL.
Cesium-137 (137Cs) was not detected in any ESER sample.
Isotopes of uranium (234U, 235U, or 238U) were detected in numerous INL contractor quarterly composites at levels which indicate their origin as naturally occurring.
The INL contractor reported one detection of 241Am in one sample. Plutonium 239/240 was also detected in one sample. Plutonium-238 was detected in three samples. All were well within historical measurements.
Stontium-90 was detected in one quarterly composite collected by the INL contractor during 2005. The result is well below the DCG for 90Sr and within historical measurements.
Cesium-137 was detected in two INL contractor samples. The measurements are within those made historically.
During 2005, the ESER contractor collected 71 atmospheric moisture samples from four locations (Atomic City, Blackfoot, Idaho Falls, and Rexburg) using molecular sieve. Table 4-7 presents the range of values for each station by quarter.
Tritium was detected in 21 of the samples. Samples that exceeded the respective 3 sigma values ranged from a low at Blackfoot of 1.0 x 10-13 µCi/mL collected on February 15, 2005, to a high of 10.1 x 10-13 µCi/mL at Idaho Falls collected on October 14, 2005.
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 INL Site operations. The highest observed tritium concentration (from the fourth quarter at Idaho Falls) is far below the DCG for tritium in air (as hydrogen tritium oxygen [HTO]) of 1 x 10-7 µCi/mL.
The INL contractor collected atmospheric moisture samples at the EFS and at Van
Buren Boulevard on the INL and at Idaho Falls and Craters of the Moon off the
INL. They collect from one to three samples at each location each quarter.
During 2005, 41 samples were collected. Seven samples indicated an activity
greater than its 3 sigma level. The samples ranged from a low of
4.8 ± x 10-13 µCi/mL at Craters of the Moon taken on March 9, 2005, to a high of 225 x 10-13 µCi/mL collected on June 15, 2005 (Table 4-8). All values are consistent with ESER contractor results and are less than the DCG for tritium in air.
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The ESER contractor collects precipitation samples weekly at the EFS and monthly at the Central Facilities Area (CFA) and offsite in Idaho Falls. A total of 35 precipitation samples were collected during 2005 from the three sites. Tritium concentrations were measured above the 3 sigma uncertainty level in 11 samples and results ranged from 77.1 to 306.0 pCi/L. Table 4-9 shows the maximum concentration by quarter for each location. The highest radioactivity was from a sample collected at EFS during the fourth quarter and is far below the DCG level for tritium in water of 2 x 106 pCi/L. The concentrations are well within the normal range observed historically at the INL Site. The maximum concentration measured since 1998 was 553 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/).
In 2005, both the ESER and INL 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 INL Site stations. This is mostly caused by agricultural activities in offsite areas.
The total suspended particulate concentrations measured by the INL 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 INL Site 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 2005. 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 0.0 to 44.8 µg/m3. At the Blackfoot Community Monitoring Station, 60 valid samples were collected from January through December. Concentrations ranged from 0.07 to 42.4 µg/m3. At Atomic City, 59 valid samples were collected from January through December. Concentrations ranged from 0.1 to 52.5 µg/m3. All measurements were less than the EPA standard for mean annual concentration.
Nitrogen dioxide is monitored at the Experimental Breeder Reactor II auxiliary boilers at MFC. 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.
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.
More IMPROVE data and information can be accessed at http://vista.cira.colostate.edu/improve .
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Gross alpha and gross beta activity were determined on all waste management samples collected by the ICP contractor in 2005. Low-volume suspended particle (SP) monitors collected particulate material on 10-cm (4-in) membrance filters.
Samples had gross alpha measurements that exceeded their 3 sigma uncertainty
ranging from a high of 4.87 x 10-15 µCi/mL in the first half of December at
location Howe 400.3 to a low of
0.27 x 10-17 µCi/mL in the second half of March at location Subsurface Disposal Area (SDA) 4.3. The annual mean for gross alpha was 7.13 x 10-16 µCi/mL. SP gross beta levels ranged from a high of 7.33 x 10-14 µCi/mL in the first half of December at Howe 400.3 to a low of 1.95 x 10-15 µCi/mL at SDA 4.3 in the second half of March. The gross beta annual mean was 9.23 x 10-15 µCi/mL.
The only anthropogenic gamma-emitting radionuclide detected in 2005 that exceeded the three-sigma error was 137Cs. In March, 137Cs was found in the Location A , SDA, filter (3.6 x 10-15 µCi/mL) and in June at ARA (3.1 x 10-15 µCi/mL). This gamma detections were significantly below the DCG for air at 4.0 x 10-10 µCi/mL. This is consistent with what was seen in the past from resuspended soils containing activity due to fallout.
Radiochemical analysis showed no detections of alpha- and beta-emitting radionuclides greater than the 3 sigma error. No trends were detected based on analytical results from calendar year 2005.
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40 Code of Federal Regulations, Part 50.6, “National Primary and Secondary Ambient Air Quality Standards for Particulate Matter,” Code of Federal Regulations, Office of the Federal Register.
40 Code of Federal Regulations, Part 61, “National Emission Standards for Hazardous Air Pollutants,” Code of Federal Regulations, Office of the Federal Register.
EG&G of Idaho, Inc., 1993, New Production Reactor Exposure pathways at the INEL, EGG-NPR-8957.
U.S. Department of Energy-Idaho Operations Office (DOE-ID), 2006, National Emissions Standards for Hazardous Air Pollutants (NESHAPs) – Calendar year 2005 INEL Report for Radionuclides, DOE/NE-ID-10890(05).
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