M. Case - S. M. Stoller Corporation
M. Verdoorn - Battelle Energy Alliance
R. Wilhelmsen - CH2M-WG Idaho
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 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 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 at the INL Site.
The INL contractor monitors airborne effluents at individual INL Site 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 2006.
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 2006. 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.
Airborne effluents are measured at or estimated for regulated facilities as required under the Idaho State Implementation Plan. 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 2006, an estimated 6,340 Ci of radioactivity were released to the atmosphere from all INL Site sources. The National Emissions Standards for Hazardous Air Pollutants (NESHAP) Calendar Year 2006 INL Report for Radionuclides (DOE-ID 2007) 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 (Table 4-2a , Table 4-2b , Table 4-2c , Table 4-2d , Table 4-2e ) 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.
The largest facility contributions to the total emissions came from the Idaho
Nuclear Technology and Engineering Center (INTEC) at 57 percent, Reactor
Technology Complex (RTC) at approximately 22 percent, the Materials and Fuels
Complex (MFC) at 19 percent, and the Radioactive Waste Management Complex (RWMC)
at 1 percent [Table 4-2 (Table 4-2a
, Table 4-2b
, Table 4-2c
, Table 4-2d
, Table 4-2e
)
]. Approximately 88 percent
of the radioactive effluent was in the form of noble gases (argon, krypton, and
xenon) and most of the remaining effluent was tritium.
Both the ESER and INL Site 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 2006, the ESER contractor analyzed 936 cartridges, looking specifically for 131I. No 131I was detected in any of the individual ESER samples.
The INL Site contractor collected and analyzed 1,201 cartridges. Iodine was detected in excess of the 3 sigma value in one sample collected at RTC at a level of 5.06 x 10-15 µCi/mL.
Particulates filtered from the air were sampled 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 concentrations 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 0.4 x 10-15 µCi/mL at Craters of the Moon during the week ending December 12, 2006, to a maximum of 8.0 x 10-15 µCi/mL during the week ending September 13, 2006, at the Mud Lake replicate sampler. Concentrations measured by the INL contractor that exceeded their 3 sigma uncertainty ranged from a low of 0.4 x 10-15 µCi/mL collected at Craters of the Moon on January 4, 2006, to a high of 49.0 x 10-15 µCi/mL collected at Naval Reactors Facility NRF) on September 6, 2006.
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 - 2005. 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 third quarter of 2006. The maximum median weekly gross alpha concentration was 5.3 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 1.3 x 10-15 μCi/mL at the FAA tower to 2.1 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 8.8 x 10-16 μCi/mL at the Craters of the Moon to 1.6 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 eight-year period from 1999 through 2006 (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 0.3 x 10-14 µCi/mL on January 4, 2006, at Jackson to a high of 5.8 x 10-14 µCi/mL at Jackson on December 13, 2006. Concentrations measured above 3 sigma by the INL contractor ranged from a low of 0.4 x 10-14 µCi/mL at Gate 4 on July 5, 2006, to a high of 8.1 x 10-14 µCi/mL at Location A on October 4, 2006.
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 1999-2005. 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 2006 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 2.1 x 10-14 µCi/mL at Craters of the Moon to 2.6 x 10-14 µCi/mL at the EFS. INL contractor data ranged from an annual median of 1.2 x 10-14 µCi/mL at Idaho Falls to 2.8 x 10-14 µCi/mL at Gate 4. In general, the levels of airborne radioactivity for the three groups (INL Site, boundary, and distant locations) tracked each other closely throughout the year. 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 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.
Gross beta concentrations, unlike gross alpha concentrations, are typically detected above the 3s uncertainty levels. They 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 2006 by the ESER contractor. The results are grouped by location (that is, INL Site, boundary, and distant stations). Looking at the graph, 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 2006.
There were a few statistical differences between weekly boundary and distant data sets collected by the ESER contractor during the 52 weeks of 2006. The differences observed can be attributed to expected statistical variation in the data.
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 three quarterly composited samples collected onsite at EFS and at boundary locations Howe and Mud Lake. A frequency plot of 241Am concentrations detected in ESER contractor samples over the past ten years is shown in Figure 4-7 . The results detected in 2006 are within the range measured historically all well below the 241Am DCG of 20,000 x 10-18 µCi/mL.
Plutonium isotopes were detected in some onsite and boundary ESER samples in 2006. Valid 239/240Pu 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 two onsite and three boundary ESER samples within the range of historical measurements (Figure 4-9 ). The values measured are much below the DCG of 9,000,000 x 10-18 µCi/mL.
Cesium-137 (137Cs) was detected in four ESER samples at onsite, boundary and distant locations. All were well with historical measurements and below the DCG.
The INL contractor reported the detection of 241Am in seven samples. The detections showed no temporal or spatial pattern and, with the exception of the Central Facilities Area (CFA) sample taken in the first quarter, were within the range of historical results. In addition to 241Am, 238Pu and 239/240Pu were detected in the CFA sample. The 238Pu was within the historical range. The analytical results for 241Am and 239/240Pu in the field samples are similar to those of a spiked sample. After discussions with the analytical laboratory, it was concluded that the analytical instrument could have become contaminated between analyses and that the results are thus considered to be invalid. A review of site operations for this period showed no abnormal release events and supports this decision. Stontium-90 was not detected in any sample collected by the INL contractor during 2006.
Cesium-137 was detected in six INL contractor samples within the 1997-2005 range of values.
Isotopes of uranium (234U, 235U, or 238U) were detected in numerous INL contractor quarterly composites at levels which indicate their origin as naturally occurring. They are therefore not reported.
During 2006 the ESER contractor collected 71 atmospheric moisture samples from four locations (Atomic City, Blackfoot, Idaho Falls, and Rexburg) using molecular sieve material. 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 Atomic City of 2.6 x 10-13 µCi/mL to a high of 14.2 x 10-13 µCi/mL at Rexburg.
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 is far below the DCG for tritium in air (as hydrogen tritium oxygen) 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 Site and at Idaho Falls and Craters of the Moon off the INL Site (Table 4-8 ). During 2006, 50 samples were collected. Tritium detected above the three sigma level ranged from a low of 4.8 x 10-13 µCi/mL at Craters of the Moon to a high of 225 x 10-13 µCi/mL at Van Buren Avenue. All values are 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 44 precipitation samples were collected during 2006 from the three sites. Tritium concentrations were measured above the 3 sigma uncertainty level in seven samples and results ranged from 199 to 274 pCi/L. Table 4-9 shows the maximum concentration by quarter for each location. The highest radioactivity was from a sample collected at CFA during the second 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 2006, 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 0.0 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 influenced by agricultural activities in offsite areas.
The total suspended particulate concentrations measured by the INL contractor ranged from 0.0 µg/m3 at numerous locations and dates to 518 µg/m3 at Craters of the Moon. Sample particulate concentrations were generally higher at distant locations than at the INL Site stations. The high level at Craters of the Moon is due to road construction on U.S. Highway 26 and reached its maximum value during the August 16, 2006, sample period.
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 55 valid 24-hour samples at Rexburg from January through December 2006. 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 0.3 to 50.1 µg/m3. At Atomic City, 58 valid samples were collected from January through December. Concentrations ranged from 0.0 to 66.1µg/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 .
Samples of airborne particulate material were collected from waste management areas by the ICP contractor in 2006. Samples were obtained using suspended particle (SP) monitors. Gross alpha and gross beta activity were determined on all SP samples. Table 4-10 shows the SP monitoring results.
No human-made gamma-emitting radionuclides were detected in 2006 that exceeded the three-sigma error.
Table 4-11 shows radiochemical detections of alpha- and beta-emitting radionuclides greater than the three-sigma error for 2006. These detections are consistent with levels measured in resuspended soils at the RWMC in previous years. No trends in airborne radioactivity were indicated by the monitoring results from calendar year 2006.
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.
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), 2007, National Emissions Standards for Hazardous Air Pollutants (NESHAPs)
– Calendar year 2006 INEL Report for Radionuclides, DOE/NE-ID-10890(05).