This report for the fourth quarter, 2002, contains results from the Environmental Surveillance, Education and Research (ESER) Program’s monitoring of the Department of Energy’s Idaho National Engineering and Environmental Laboratory’s (INEEL) offsite environment, October 1 through December 31, 2002. All sample types (media) and the sampling schedule followed during 2002 are listed in Appendix A. Specifically, this report contains the results for the following:
Gross alpha and gross beta measurements are used as general indicators of the presence of alpha-emitting and beta-emitting radionuclides in air. Gross alpha and gross beta results were found to have no discernable statistical distribution during the fourth quarter of 2002. Because of this, these data were statistically analyzed using nonparametric methods, including the use of the median to represent central tendency. At no time during the fourth quarter were gross alpha concentrations from Boundary locations statistically higher than corresponding data sets for Distant locations, as one would expect if the INEEL were a significant source of radionuclide contamination. There were no statistical differences between gross alpha or gross beta results when grouped by location on a quarterly or monthly basis. No statistical gross alpha differences were noted in weekly analyses of Boundary and Distant locations. Gross beta concentrations measured at Boundary locations were statistically greater than those measured at Distant locations during the weeks of November 13, November 20, and December 3 and 17, 2002. Additional investigation on a weekly basis concluded that the Mud Lake sample was much higher than the other locations. The values during these weeks were still within the range of historical levels, and are attributed to resuspension of particulates from the surrounding recently harvested or fallow fields. Also, the collection week ending on December 3, 2002 was subject to a series of strong temperature inversion conditions, which act to trap radon gas and its progeny.
During the fourth quarter, no iodine-131 (131I) was measured in any cartridge batch above the associated 2s or MDC values.
Selected quarterly composite filter samples were analyzed for gamma emitting radionuclides, strontium-90 (90Sr), plutonium-238 (238Pu), plutonium-239/240 (239/240Pu), and americium-241 (241Am). Seven samples collected from air monitoring stations located at the Experimental Field Station (EFS), FAA Tower, Howe and Howe Q/A, Idaho Falls, Monteview, and Van Buren Gate showed at least one human-made radionuclide (241Am, 239,240Pu, 90Sr or cesium-137 [137Cs]) greater than their related 2s values. All values were within the range of those measured in the past and are likely due to resuspension of particulate fallout from past nuclear weapons testing. All results were far less than their respective DOE Derived Concentration Guide (DCG) values.
Eight atmospheric moisture samples and three duplicates were obtained during the fourth quarter of 2002. Seven samples exceeded their respective 2s values. The maximum value (3.8 x 10-12 mCi/mL of air [1.4 x 10-7 Bq/mL of air]) from these seven sample results was well below the DOE DCG for tritium in air of 1 x 10-7 mCi/mL (3.7 x 10-3 Bq/mL).
The ESER Program operates three PM10 samplers, one each at Rexburg, Blackfoot, and Atomic City. Sampling of PM10 is informational as no analyses are conducted for contaminants. PM10 concentrations were well below all health standard levels for all samples. The maximum 24-hour concentration was 92.5 µg/m3 on October 22, 2002, at Atomic City.
Storm events in the fourth quarter of 2002 produced enough precipitation for a total of eight samples and one split – three and a split from Idaho Falls, two from CFA, and three from the EFS. Tritium was detected above the 2s concentration in six samples. While there is no regulatory limit for tritium in precipitation, the DOE DCG and maximum contaminant level set by EPA for tritium in drinking water can be used as screening values. The highest tritium concentration, 212.0 ± 58.7 pCi/L (7.9 ± 2.2 Bq/L), was measured in the split sample collected from CFA on December 12, 2002. This value is many times lower than the DCG value (2 x 106 pCi/L) and the Safe Drinking Water Act limit (20,000 pCi/L) for tritium in drinking water.
Drinking water samples were collected from fourteen locations around the Snake River Plain. Samples are analyzed for gross alpha, gross beta, and tritium. Gross alpha in a single sample from Minidoka was greater than its associated 2s value. All samples exceeded their 2s value for gross beta. Six samples exceeded their respective 2s value for tritium. Detections of gross alpha and gross beta are not unusual on the Snake River Plain and are attributable to dissolution of naturally occurring radionuclides into the groundwater as it flows beneath the Plain. The gross alpha detection and tritium measurement were well below the EPA MCLs of 8 pCi/L and 20,000 pCi/L, respectively. The maximum gross beta detection of 8.31 ± 1.05 pCi/l was also below the EPA screening value of 50 pCi/L.
Five surface water samples and a duplicate were collected from various locations near the discharge of the Snake River Plain Aquifer into the Snake River. None of the samples had measurable levels of gross alpha. The Twin Falls sample and duplicate were the only samples to exceed the 2s value for tritium. The maximum concentration was well below the DOE and EPA regulatory limits. All six samples had gross beta concentrations above their 2s value. The maximum concentration of gross beta detected was below the EPA screening concentration of 50 pCi/L. As discussed above for drinking water it is not unusual to detect gross activity in water discharging from groundwater.
Milk samples were collected weekly in Idaho Falls and monthly at nine other locations around the INEEL. All samples were analyzed for gamma emitting radionuclides. None of the samples had 137Cs concentrations above the 2s concentration. Only one sample, from Roberts in October, had detectable 131I. Strontium-90 was measured in four samples above the 2s value. There are no established limits for radionuclides in milk but, for comparison, the EPA limits set for radionuclides in water can be used. The EPA has set the limit for 90Sr in drinking water at 8 pCi/L (0.3 Bq/L). The Safe Drinking Water limit is based on a 4 mrem per year maximum allowable dose and the assumption that two liters per day are consumed. The maximum 90Sr concentrations detected in milk during the fourth quarter were all lower than this limit.
Potatoes were collected from a total of nine local and out-of-state locations in 2002. Samples were analyzed for gamma emitting radionuclides and 90Sr. None of the samples contained measurable 90Sr. Only one sample had measurable 137Cs above the 2s value.
Three large game animals were sampled during the fourth quarter of 2002. All were killed as a result of vehicular collisions. These accidents all involved two mule deer (Odocoileus hemionus) and an elk (Cervus elaphus). Every effort was made to collect thyroid, liver, and muscle tissue from each animal. However, certain tissues could not be collected from all animals due to their condition at the time of collection. No 131I was measured in any game sample collected during the fourth quarter of 2002. One sample of elk liver tissue contained 137Cs above the 2s uncertainty.
Eleven waterfowl were collected during 2002: two each from the control locations of Mud Lake and Heise, three from the northeast Test Reactor Area (TRA) pond, and four from the TAN pond. All were analyzed for gamma emitting radionuclides with a subset analyzed for 90Sr, 238Pu, 239/240Pu, and 241Am. Seven waterfowl had measurable levels of at least one radionuclide in edible tissue. Only curium-141 (141Cm), niobium-95 (95Nb) and 90Sr were detected at greater than their respective 2s concentration in the edible portion of three of the waterfowl. The birds came one each from Mud Lake, the NE TRA cold pond, and INEEL TAN, respectively. The maximum potential dose from eating 225 g (8 oz) of meat from ducks collected in 2002 was estimated to be 0.004 mrem. This dose is far less than the 10 mrem per year dose set by EPA and well below the 100 mrem per year regulatory dose limit set by DOE.
Environmental dosimeter locations are divided into
Boundary and Distant groupings. Exposure rates measured during the later
half of 2002 were similar to those recorded in the past. The boundary
exposure rates ranged from 0.28 to 0.37 mR/day. The overall average was
0.33 mR/day. The Distant set ranged from 0.30 to 0.41 mR/day. The
average Distant value was also 0.33 mR/day. No statistical difference
existed between Boundary and Distant locations.