To help assess the impact of contaminants released to the environment by operations at the Idaho National Laboratory (INL) Site, agricultural products (milk, lettuce, wheat, potatoes, and sheep); wildlife (waterfowl and large mammals) and soil were sampled and analyzed for radionuclides. In addition, direct radiation was measured on and off the INL Site in 2005.
Some human-made radionuclides were detected in agricultural products and soil samples. However, the results could not be directly linked to operations at the INL Site. Concentrations of radionuclides detected in agricultural products and soil samples were consistent with fallout levels from atmospheric weapons testing. The maximum levels for these radionuclides were all well below regulatory health-based limits for protection of human health and the environment. Some human-made radionuclides were also detected in samples of wildlife during 2005 but concentrations were similar to those found in samples taken off the INL Site.
Direct radiation measurements made at offsite, boundary, and onsite (except in the vicinity of some INL Site facilities) locations were consistent with background levels. The measured annual dose equivalent from external exposure was 124 mrem. Radiation measurements taken in the vicinity of waste storage and soil contamination areas near INL Site facilities were consistent with previous measurements. Direct radiation measurements using a radiometric scanner system at the Radioactive Waste Management Complex were greater than background levels but consistent with those made historically at that location.
This chapter provides a summary of the various environmental monitoring activities currently being conducted on and around the Idaho National Laboratory (INL) Site (Table 7-1). These media are potential pathways for transport of INL Site contaminants to nearby populations.
The INL and Idaho Cleanup Project (ICP) contractors monitored soil, vegetation, and direct radiation on the INL Site to comply with applicable U.S. Department of Energy (DOE) orders and other requirements. The contractors collected 418 soil, vegetation, and direct radiation samples for analysis in 2005.
The Environmental Surveillance, Education and Research Program (ESER) contractor conducted offsite environmental surveillance and collected samples from an area of approximately 23,308 km2 (9000 mi2) of southeastern Idaho at locations on, around, and distant to the INL Site. The ESER contractor collected approximately 225 agricultural products, wildlife, and direct radiation samples for analysis in 2005.
Section 7.1 presents the agricultural products and wildlife surveillance results sampled under the ESER Program. Section 7.2 presents the results of soil sampling by both the ESER contractor and the INL and ICP contractors. The direct radiation surveillance results are presented in Section 7.3. Results of the waste management surveillance activities are discussed in Section 7.4.
During 2005, 152 milk samples were collected under the ESER Program. All of the samples were analyzed for gamma-emitting radionuclides including iodine-131 (131I). During the second and fourth quarters, nine samples were analyzed for strontium-90 (90Sr) and tritium.
Iodine-131 was not detected in any sample in 2005. Cesium-137 (137Cs) was detected in one sample collected in Idaho Falls in July. The result, 3.1 pCi/L, is well below the DOE derived concentration guide (DCG) for 137Cs in water of 3000 pCi/L.
Strontium-90 was detected in eight out of nine samples, ranging from 0.3 pCi/L at Moreland to 1.2 pCi/L at Carey. All levels of 90Sr in milk were consistent with those data previously reported by the U.S. Environmental Protection Agency (EPA) as resulting from worldwide fallout deposited on soil and taken up by ingestion of grass by cows (EPA 1995). The maximum value is far lower than the DOE DCG for 90Sr in water of 1000 pCi/L.
Tritium was not detected in any of the nine samples analyzed.
ESER Program personnel collect lettuce samples every year from the areas adjacent to the INL Site. The collection of lettuce from home gardens around the INL Site typically depends on availability. To make this sampling more reliable, ESER added two prototype lettuce planters in conjunction with other sampling locations at Atomic City and the Experimental Field Station (EFS) on the INL Site. These locations are relatively remote and have no access to water, requiring that a self-watering system be developed. This method allows for the placement and collection of lettuce at areas previously unavailable to the public (i.e., on the INL Site). The boxes are set out in the spring with the lettuce grown from seed. This new method also allows for the accumulation of deposited radionuclides on the plant surface throughout the growth cycle.
Seven lettuce samples, including one duplicate, were collected from regional private gardens at Arco, Blackfoot, Howe, Idaho Falls, Mud Lake, and Pocatello (Figure 7-1). One sample was collected from the portable lettuce garden placed at Atomic City. The lettuce crop at EFS failed due to yellow jackets nesting in the soil.
Strontium-90 was detected above the 3s level in the sample collected from Pocatello in 2005. Strontium-90 in lettuce results from plant uptake of this isotope in soil as well as deposition from airborne dust containing 90Sr. Strontium-90 is present in soil as a residual of fallout from aboveground nuclear weapons testing, which took place between 1945 and 1980. The concentration of 9.3 × 10-2 pCi/g was within concentrations detected historically (Table 7-2) and was most likely from weapons testing fallout.
None of the 12 wheat samples (including one duplicate) collected during 2005 contained a measurable concentration of 90Sr above the 3s uncertainty level. No other anthropogenic radionuclides were detected (Table 7-3).
Ten potato samples, including one duplicate, were collected during 2005: six samples and one duplicate from distant locations; three samples from boundary locations; and one sample from an out-of-state location (Colorado) (Figure 7-1). The nine Idaho samples were collected from Aberdeen, Arco, Blackfoot, Fort Hall, Idaho Falls, Monteview, Rupert, Terreton, and Taber. Strontium-90 was detected in three of the Idaho samples at levels ranging from 0.8 pCi/kg at Idaho Falls to 1.1 pCi/kg at Fort Hall. Strontium-90 is present in soil as a result of fallout from aboveground nuclear weapons testing, and these detections were most likely from that fallout. No other anthropogenic radionuclides were detected in potatoes.
Certain areas of the INL Site are open to grazing under lease agreements managed by the U.S. Bureau of Land Management. Every year, during the second quarter, ESER personnel collect samples from sheep grazed in these areas, either just before or shortly after they leave the INL Site. Muscle, liver, and thyroid samples were collected from each animal. For the calendar year 2005, six sheep were sampled. Four were from INL Site land, and two were from Dubois to serve as control samples. Cesium-137 was detected above 3s in the muscle tissue of one onsite sample at a level of 4.9 pCi/kg, but was not detected in offsite muscle samples. Cesium-137 was also detected in the liver tissue sample from one onsite animal at a level of 5.5 pCi/kg. Cesium-137 was not measured above the 3s uncertainty in any control sheep in 2005. All 137Cs concentrations measured in 2005 were similar to those found in both onsite and offsite sheep samples in previous years and are within historical values. Cesium-137 concentrations in both sheep liver and muscle have been essentially the same (error bars overlap) since 2000 (Figure 7-2).
Levels of 131I are of particular interest in thyroids because of this organ’s ability to accumulate iodine. Iodine-131 did not exceed the 3s uncertainty in any sample.
Muscle, liver, and thyroid samples were collected from three pronghorn and two mule deer which were accidentally killed on INL Site roads or died from natural causes. There was detectable 137Cs radioactivity above 3s in the muscle of one pronghorn taken on or near the INL Site. The result was 4.0 pCi/kg. No tissue samples contained detectable 131I above 3s.
In 1998 and 1999, four pronghorn, five elk, and eight mule deer muscle samples were collected as background samples from hunters across the Western United States: three from central Idaho; three from Wyoming; three from Montana; four from Utah; and one each from New Mexico, Colorado, Nevada, and Oregon. Each background sample had small, but detectable, 137Cs concentrations in its muscle ranging from 5.1 to 15 pCi/kg.
The concentration of 137Cs detected in the muscle sample collected in 2005 was below this range. The 2005 results were also within the range of historical values. These values can be attributed to the ingestion of radionuclides in plants from worldwide fallout associated with aboveground nuclear weapons testing. No 131I was detected in any of the thyroid gland samples.
No marmots were collected during 2005.
Nine ducks were collected during 2005. Three were collected from wastewater ponds located at the Reactor Technology Complex (RTC) facility, three came from wastewater ponds near the Materials and Fuels Complex (MFC) facility, and three control samples were collected near Firth. Each duck sample was divided into three sub-samples: one consisting of edible tissue (muscle, gizzard, heart and liver); viscera; and a remainder sample that includes all remaining tissue (bones, feathers, feet, bill, head, and residual muscle). All were analyzed for gamma emitting radionuclides, 90Sr, 238Pu, 239/240Pu, and 241Am. Concentrations of radionuclides measured in edible tissues are shown in Table 7-4.
Several manmade radionuclides were detected in the samples taken from the RTC ponds. These included 241Am, 137Cs, Cobalt-60 (60Co), Manganese-54 (54Mn), Plutonium-239 (239Pu), 239/240Pu, 90Sr, and Zinc-65 (65Zn). Of these eight, five (137Cs, 60Co, 90Sr, 241Am, and 65Zn) were found in the edible tissues. Two radionuclides, 241Am and 90Sr, were detected in the birds from the MFC ponds, however these detections are within historical levels attributable to fallout . No manmade radionuclides were found in the control samples.
Since manmade radionuclides were only found in ducks taken from the INL Site, it is assumed that the INL Site is the source of these detections. Concentrations of the detected radionuclides from RTC were higher than those found in the previous few years, but still lower than those in ducks taken during a 1994-1998 study (Warren et al. 2001). The ducks were not taken directly from the two-celled hypalon-lined radioactive wastewater RTC Evaporation Pond but from an adjacent sewage lagoon. However, it is likely that the birds also used the RTC Evaporation Pond as they were observed in the area for about two weeks prior to collection. Ducks collected in previous years were sampled later during the hunting season and did not reside at the ponds (i.e., were migrating).
RTC Evaporation Pond effluent data for several years were examined as a potential explanation for the increase in waterfowl radionuclide concentrations. Radionuclide amounts in effluent were cumulated to determine the pond source term for each year from 2003 through 2005. The RTC Evaporation Pond source terms for 137Cs (the radionuclide responsible for 98 percent of the calculated doses) over this time period do not correlate with the increased dose estimated for 2005 ducks. There was no significant increase between 2004 and 2005, as one would expect if the increased radionuclide concentrations are correlated with a source term increase (the maximum concentration of 137Cs in any of the waterfowl tissues sampled was 0.2 pCi/g in 2004 and 16.6 pCi/g in 2005). However, that does not preclude the sediment or vegetation, where radionuclides can accumulate, as a source of 137Cs.
Waterfowl hunting is not allowed on the INL Site, but a maximum potential exposure scenario to humans would be someone collecting a contaminated duck directly from the ponds and immediately consuming all muscle, liver, heart, and gizzard tissue (average 225 g). The maximum potential dose from eating 225 g (8 oz) of meat from the most contaminated waterfowl collected in 2005 was estimated to be 0.19 mrem (.0019 mSv) (Chapter 8). Although higher than in recent years, this dose was within expected variability when dealing with biological (and unpredictable) media. This dose is not the maximum dose ever estimated. The maximum dose estimated for the period from 1993 through 1998 was 0.89 mrem (0.009 mSv) and from 2000 through 2004 was 0.08 mrem (0.0008 mSv). In the late 1970s, when the percolation ponds were still in use, the maximum dose estimated from eating a contaminated duck was estimated to be 54 mrem (0.54 mSv).
Three mourning dove samples were collected in 2005. One came from the MFC facility, and two were from offiste locations. None of the samples contained detectable manmade radionuclides.
MFC also collects random vegetation samples (at the same locations as the soil samples) and other areas of concern. Vegetation is sampled and is used to determine windblown deposition and changes in plant uptake. Approximately 1 kg (2.2 lb) of mixed vegetation is collected and dried. The dried material is then powdered and analyzed for various radionuclides. Table 7-5 presents the 2005 vegetation results for MFC.
Soils are sampled to determine if long-term deposition of airborne materials from the INL have resulted in a buildup of radionuclides. The sampling also supports the Wastewater Land Application Permit (WLAP) for the Central Facilities Area (CFA) Sewage Treatment Plant.
Soil samples are analyzed for gamma-emitting radionuclides, 90Sr, and certain actinides. Aboveground nuclear weapons testing has resulted in many radionuclides being distributed throughout the world. Cesium-137, 90Sr, 238Pu, 239/240Pu, and 241Am (which potentially could be released from INL operations) are of particular interest because of their abundance owing to nuclear fission events (e.g., 137Cs and 90Sr) or from their persistence in the environment because of long half-lives (e.g., 239/240Pu, with a half-life of 24,390 years). Levels found around INL facilities are consistent with fallout levels. Soil sampling locations are shown in Figure 7-3.
The ESER contractor collects offsite soil samples every two years (in even years); thus, soil sampling was not conducted in 2005. Results from 1975 to 2004 are presented in Figure 7-4. The geometric means were used because the data were log-normally skewed. The shorter-lived radionuclides (90Sr and 137Cs) show overall decreases through time.
Radionuclide levels in soils at 175 site surveillance locations near major INL facilities were measured by the INL and ICP contractors in 2005 using in situ gamma spectrometry, with 20 additional grab samples collected from 0-5 cm (0-2 in.) at selected locations. Table 7-6 summarizes the in situ gamma results, and Table 7-7summarizes the analytical laboratory gamma and radiochemistry results. Uranium isotopes were detected in all samples at levels that indicated they were from natural sources.
At MFC, seven locations and one duplicate were sampled and analyzed for low-level gamma-emitting radionuclides and for uranium, plutonium, and thorium isotopes. Table 7-8 presents the results of the 2005 sampling effort.
The WLAP for the CFA Sewage Treatment Plant allows for nonradioactive wastewater to be pumped from the treatment lagoons to the ground surface by sprinkler irrigation (DOE‑ID 1999, IDEQ 2000, Johnston 2005). Soils are sampled at ten locations within the CFA land application area following each application season. Subsamples are taken from 0 to 30 cm (0 to 12 in.), 30 to 61 cm (12 to 24 in.), and 61-91 cm (24 to 36 in.) at each location and composited for each depth interval, yielding three samples, one from each depth. These samples are analyzed for pH, electrical conductivity, sodium absorption ratio, percent organic matter, extractable phosphorus, and nitrogen, in accordance with the WLAP, to determine whether wastewater application is adversely affecting soil chemistry. The analytical results for the soil samples are summarized in Table 7-9. The 61-91 cm (24 to 36 in.) depth interval is a new permit requirement for 2005; therefore no historical data are available for this interval. Data collected by Cascade Earth Sciences, Ltd. in 1993, prior to wastewater application, is presented in Table 7-9 for comparison purposes.
During 2005, pH levels were similar to the 1995-2004 historical averages at the 0-30 cm (0-12 in.) and 30-61 cm (12-24 in.) depths (no historical data is available for 61-91 cm [24-36 in.] depth). Percent organic matter was below the 1995 to 2004 historical average levels at 0-30 cm (0-12 in.) and 30-91 cm (12-24 in.) depths.
Soil salinity levels between 0 to 2 mmhos/cm are generally accepted to have negligible effects on plant growth (Bohn et al. 1985). During 2005, the electrical conductivity represented the historic highs at both the 0 to 30 cm (0 to 12 in.) and the 30 to 61 cm (12 to 24 in.) intervals, and it was near or above the 2 mmhos/cm at all three depths. Soils with sodium adsorption ratios (SARs) below 15 are generally classified as not having sodium or salinity problems (Bohn et al. 1985). During 2005, SARs were elevated at the upper depth relative to preapplication SARs; however, both depths remain well below the ratio generally indicating a sodium problem in soil.
Nitrogen data suggest negligible nitrogen accumulation from wastewater
application. The low soil-available nitrogen (ammonium-nitrogen and
nitrate-nitrogen) concentrations suggest that the native sagebrush and grass
vegetation use all of the plant-available nitrogen and that the total nitrogen
application is low. Increased nutrients and water from wastewater application
may be stimulating plant growth, which in turn rapidly utilizes plant available
nitrogen. The ammonium and nitrate nitrogen concentrations are comparable to
those of nonfertilized agricultural soils.
In 2005, available phosphorus concentrations exceeded the historical high at the
0-30.5 cm (0-12 in.) depth interval; however, concentrations remained below
preapplication levels and less than that considered adequate for range and
pasture crop growth (EPA 1981).
Soil sampling and analysis will continue, as required by the WLAP, to evaluate the impacts of wastewater application on soil chemistry.
Thermoluminescent dosimeters (TLDs) measure cumulative exposures to ambient ionizing radiation. The TLDs detect changes in ambient exposures attributed to handling, processing, transporting, or disposing of radioactive materials. The TLDs are sensitive to beta energies greater than 200 kilo-electron volts (KeV) and to gamma energies greater than 10 KeV. The TLD packets contain four lithium fluoride chips and are placed about 1 m (approximately 3 ft) above the ground at specified locations. The four chips provide replicate measurements at each location. The TLD packets are replaced in May and November of each year. The sampling periods for 2005 were from November 2004 through April 2005 (spring) and from May 2005 through October 2005 (fall).
The measured cumulative environmental radiation exposure for offsite locations from November 2004 through October 2005 is shown in Table 7-10 for two adjacent sets of dosimeters maintained by the ESER and Site contractors. For purposes of comparison, annual exposures from 2001-2004 are also included for each location.
The mean annual exposures from distant locations in 2005 were 121 ± 3 milliroentgens (mR) as measured by the ESER dosimeters and 119 ± 3 mR as measured by the Site contractor dosimeters (Table 7-10). For boundary locations, the mean annual exposures were 120 ± 3 mR as measured by ESER contractor dosimeters and 119 ± 4 mR as measured by INL Site contractor dosimeters. Using both ESER and INL Site contractors’ data, the average dose equivalent of the distant group was 124 millirem (mrem), when a dose equivalent conversion factor of 1.03 was used to convert from milliroentgens to millirem in tissue (NRC 1997). The average dose equivalent for the boundary group was 120 mrem.
In addition to TLDs, the ICP contractor uses a global positioning radiometric scanner system to conduct gamma radiation surveys. The global positioning radiometric scanner is mounted on a four-wheel drive vehicle. The two plastic scintillation detectors of the radiometric scanner measure gross gamma in counts per second with no coincidence corrections or energy compensation. Elevated count rates suggest possible areas of contamination or elevated background areas. Both global positioning system and radiometric data are continuously recorded. The vehicle is driven at approximately 8 km/hour (5 mph) to collect survey data (see Section 7.4, Waste Management Surveillance Sampling).
Onsite TLDs maintained by the INL contractor representing the same exposure period as the offsite dosimeters are shown in Appendix D, Figures D-1 through D-10. The results are expressed in mR ± 1 standard deviation. Onsite dosimeters were placed on facility perimeters, concentrated in areas likely to show the highest gamma radiation readings. Other onsite dosimeters are located in the vicinity of radioactive materials storage areas. At some facilities, elevated exposures result from areas of soil contamination around the perimeter of these facilities.
The maximum exposure onsite recorded during 2005 was 333 ± 23 mR at location RWMC 41. This dosimeter is located near active waste storage and management areas. The 2005 exposure is similar to that of previous years.
Locations Reactor Technology Complex (RTC) 2, 3, and 4 are adjacent to the former radioactive disposal ponds, which have been drained and covered with clean soil and large rocks. The levels at RTC 2 and 3 are less than one third of the values in 2002 (DOE-ID 2005).
The Idaho Nuclear Technology and Engineering Center (INTEC) 20 TLD is located near a radioactive material storage area with an exposure of 280 ± 19 mR. Exposures at INTEC 20 and the INTEC Tree Farm for 2005 were all comparable to historical exposures.
Table 7-11 summarizes the calculated effective dose equivalent an individual receives on the Snake River Plain from various background radiation sources.
The terrestrial portion of natural background radiation exposure is based on concentrations of naturally occurring radionuclides found in soil samples collected from 1976 through 1993, as summarized by Jessmore, et al (1994). Concentrations of naturally occurring radionuclides in soil are not expected to change significantly over this relatively short time period. Data indicated the average concentrations of uranium-238 (238U), thorium-232 (232Th), and potassium-40 (40K) were 1.5, 1.3, and 19 pCi/g, respectively. The calculated external dose equivalent received by a member of the public from 238U plus decay products, 232Th plus decay products, and 40K based on the above average area soil concentrations were 21, 28, and 27 mrem/year, respectively, for a total of 76 mrem/year (Table 7-10). Because snow cover can reduce the effective dose equivalent Idaho residents receive from the soil, a correction factor must be made each year to the above estimate of 76 mrem/year. For 2005, this resulted in a corrected dose of 70 mrem/year because of snow cover, which ranged from 2.54 to 25.4 cm (1 to 10 in.) in depth with an average of 17.7 cm (6.99 in.) over 78 days with recorded snow cover.
The cosmic component varies primarily with altitude increasing from about 26 mrem at sea level to about 48 mrem at the elevation of the INL Site at approximately 1500 m (4900 ft) (NCRP 1987). Cosmic radiation may vary slightly because of solar cycle fluctuations and other factors.
The estimated sum of the terrestrial and cosmic components of dose to a person residing on the Snake River Plain in 2005 was 118 mrem (Table 7-11). This is slightly below the 127 mrem measured at distant locations by ESER and INL TLDs after conversion from mR to mrem in tissue. Measured values are very close and within normal variability, of the calculated background doses (Table 7-10 and Table 7-11). Therefore, it is unlikely that INL Site operations contribute to background radiation levels at distant locations.
The component of background dose that varies the most is inhaled radionuclides. According to the National Council on Radiation Protection and Measurements, the major contributor of external dose equivalent received by a member of the public from 238U plus decay products are short-lived decay products of radon (NCRP 1987). The amount of radon in buildings and groundwater depends, in part, upon the natural radionuclide content of the soil and rock of the area. This also varies between buildings of a given geographic area depending upon the materials each contains, the amount of ventilation and air movement, and other factors. The United States average of 200 mrem was used in Table 7-11 for this component of the total background dose because no specific estimate for southeastern Idaho has been made and few specific measurements have been made of radon in homes in this area. Therefore, the effective dose equivalent from natural background radiation for residents in the INL Site vicinity may actually be higher or lower than the total estimated background dose of about 358 mrem shown in Table 7-11 and will vary from one location to another.
Vegetation, soil, and direct radiation sampling are performed at RWMC, and direct radiation sampling is performed at Waste Experimental Reduction Facility in compliance with DOE Order 435.1, “Radioactive Waste Management” (DOE 2001).
At the RWMC, vegetation is collected from the four major areas shown in Figure 7-5. Crested wheatgrass and perennials are collected in odd-numbered years. Control samples are collected near Frenchman’s Cabin (Figure 7-6). Due to recontouring and construction activities at the RWMC, perennials were not available for sampling in 2005.
The vegetation samples were analyzed for gamma-emitting radionuclides,
90Sr and alpha-emitting transuranics. Americium‑241 was detected in four
samples, with the maximum activity of
0.0033 pCi/g measured at the control location. Plutonium-239/240 was detected in
one sample collected on the SDA with an activity of 0.001 pCi/g. The
concentrations were all within the background range for the INL Site and
surrounding areas and are attributable to past fallout. No gamma-emmitting
radionuclides were detected.
Soil samples are collected every three years at the RWMC. Soil samples were collected during 2003; thus, no RWMC soil samples were collected in 2005.
The radiometric scanner system was used to conduct soil surface radiation (gross gamma) surveys at the SDA to complement soil sampling. The global positioning radiometric scanner is mounted on a four-wheel drive vehicle. The system includes two plastic scintillators that measure gross gamma in counts per second with no coincidence corrections or energy compensation (elevated count rates indicate possible areas of contamination or elevated background). Both the global positioning system and radiometric data are continuously recorded.
Figure 7-7 shows the radiation readings from the 2005 RWMC annual survey. The maximum activity was 30,200 cps and located near the west perimeter of the active pit. The readings around the active pit ranged from 2100 to 30,200 cps (see Table 7-12), which are higher than historical measurements for that area, and are due to increased waste handling at the active Accelerated Retrieval Project, and the Intermediate Level Transuranic Storage Facility. The maximum activity at the west end of the Trench #58 was 24,800 counts per second (cps) and is comparable to previous years’ measurements.
Pad A cannot be surveyed via the global positioning radiometric scanner because of driving restrictions.
Arthur, W.J. and Janke, D.H., 1986, “Radionuclide Concentrations in Wildlife Occurring at the Solid Radioactive Waste Disposal Area,” Northwest Science, 60 (3): 154-159.
Bohn, H.L., McNeal, B.L., and O’Connor, G.A., 1985, Soil Chemistry, 2nd edition, New York: Wiley and Sons, Inc.
Calder, W.A., III and E.J. Braun, 1983, “Scaling of Osmotic Regulation in Mammals and Birds,” American Journal of Physiology 244:R601-R606.
EG&G, 1986, Development of Criteria for Release of Idaho National Engineering Laboratory Sites Following Decontamination and Decommissioning, EGG 2400, August.
EPA, 1995, Environmental Radiation Data Reports 79 82, July 1994-June 1995.
EPA, 1981, Process Design Manual for Land Treatment of Municipal Wastewater, EPA 625/1-81-013, Table 4-26.
IDEQ, 2000, Letter to J. Graham, “INL Central Facilities Area (CFA),” September 18.
Jessmore, P. J., L. A. Lopez, and T. J. Haney, 1994, Compilation of Evaluation of INEL Radiological and Environmental Sciences Laboratory Surface Soil Sample Data for Use in Operable Unit 10-06 Baseline Risk Assessment, Draft, EGG-ER-11227, Rev. 3, June.
Johnston, J., DEQ, to J. Etheridge, BBWI, and J.F. Kotek, DOE-ID, January 26, 2005, “Central Facilities Area Sewage Treatment Facility, Wastewater Land Application Permit No. LA-000141-02 (Municipal and Industrial Wastewater),” CCN 54793.
NCRP, 1987, Exposure of the Population in the United States and Canada from Natural Background Radiation, NCRP Report No. 94, December 30.
NRC, 1997, Calculation of Annual Doses to Man From Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I, Regulatory Guide 1.109, Revision 1, October.
U.S. Department of Energy (DOE), 2001, “Radioactive Waste Management,” DOE Order 435.1, August 28.
U.S. Department of Energy-Idaho Operations Office (DOE-ID), 2004, Idaho National Engineering and Environmental Laboratory Site Environmental Report for Calendar-Year 2003, DOE/ID-12082 (03).
U.S. Department of Energy-Idaho Operations Office (DOE-ID), 1999, Letter to Idaho Division of Environmental Quality, “Wastewater Land Application Permit #LA-000141 Renewal Application and Report for the Central Facilities Area Sewage Treatment Plant,” U.S. Department of Energy, Idaho Operations Office, February 9.
Warren, R.W, Majors, S.J., and Morris, R.C., 2001. Waterfowl Uptake of Radionuclides from the TRA Evaporation Ponds and Potential Dose to Humans Consuming Them, Stoller-ESER-01-40, October.