This report for the second quarter, 2004, 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, April 1 through May 30, 2004. All sample types (media) and the sampling schedule followed during 2004 are listed in  Appendix A. Specifically, this report contains the results for the following:

• Air sampling, including air filters and charcoal cartridges, atmospheric moisture, and 10 micron particulate matter (PM₁₀);
• Water sampling, including precipitation, surface water, and drinking water;
• Agricultural product sampling, including milk, sheep, and large game;
• Measurement of external exposure, using environmental dosimetry.

Results are presented in this report with an analytical uncertainty term, s, where “s” is an estimate of the population standard deviation (assuming a normal (Guassian) distribution. The following guidelines, based on Currie (1984), are used to interpret the analytical results.

• Results greater than 3s are reported as “detected”.
• Results less than 2s are reported as “undetected”.
• Results between 2-3s are reported as “questionable” (i.e., the radionuclide might have been detected but such detection may not be considered reliable.)

Gross alpha and gross beta measurements are used as general indicators of the presence of radionuclides. Gross alpha and gross beta results were found to have no discernable statistical distribution during the second quarter of 2004. 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 second quarter were weekly, monthly, or quarterly gross alpha or gross beta concentrations in air collected at Boundary locations statistically greater than corresponding data for Distant locations, as one would expect if the INEEL were a significant source of radionuclide contamination.

Iodine-131 (¹³¹I) was not detected in any batch of charcoal cartridges during the second quarter.

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). Americium-241 and ^239/240Pu were detected in three samples collected and composited during the second quarter. Concentrations of both were below the DOE derived concentration guidelines (DCGs).

Sixteen atmospheric moisture samples were obtained during the second quarter of 2004 and analyzed for tritium. One each from Blackfoot and Rexburg, and two from Idaho Falls exceeded their respective 3s levels. The maximum value was below the DOE DCG for tritium in air.

The ESER Program operates three PM₁₀ samplers for particulate sampling, 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 particulate concentration was 45.98 mg/m³ on May 8, 2004, at the Rexburg CMS. This below the EPA Air Quality Standard of 150 mg/m³.

Sufficient precipitation occurred to allow collection of three samples; one from Idaho Falls and two weekly samples from the Experimental Field Station (EFS) on the INEEL. Tritium was not detected above the 3s level in any of the samples.

Thirteen drinking water samples and one duplicate were collected from selected taps throughout southeast Idaho during the second quarter 2004. Samples were analyzed for gross alpha, gross beta, and tritium (³H). One of the samples exceeded its 3s value for gross alpha and two others exceeded for tritium. The maximum value of both was below the EPA limits established under the Safe Drinking Water Act and DOE DCGs. Ten samples exceeded the 3s value for gross beta. The maximum gross beta concentration measured, (3.22 ± 0.89) pCi/L, was from Minidoka and was below the EPA Safe Water Drinking Water Act (SDWA) screening limit of 50 pCi/L and the DOE DCG of 100 pCi/L. Levels of gross beta activity observed are not unusual given the basaltic terrain.

Six surface water samples (including one duplicate) were collected from locations throughout southeast Idaho. Samples were analyzed for gross alpha, gross beta, and tritium (³H). None of the samples exceeded their 3s value for tritium or gross alpha. Gross beta activities were detected in four samples. Results were less that SDWA screening limits and DOE DCGs and were typical of historical and regional measurements.

Milk samples were collected weekly in Idaho Falls and monthly at eight other locations around the INEEL. All samples were analyzed for gamma-emitting radionuclides. Iodine 131 and ¹³⁷Cs concentrations were not detected in any milk sample. One of five samples had ⁹⁰Sr concentrations above the 3s value.  Tritium was not detected in any of the five samples collected.

Individual sheep from three separate flocks were sampled including a control flock in Dubois from the Experimental Sheep Station, a flock from a southern INEEL allotment, and a flock from a northern INEEL allotment. Two sheep were taken from each flock. Thyroid, muscle, and liver tissue were collected and analyzed for gamma emitting radionuclides. No ¹³¹I was found in any of the samples. Analysis for ¹³⁷Cs showed results greater than 3s in three samples from two different animals on the southern allotment: one liver and two muscle samples. All concentrations of ¹³⁷Cs were similar to those found in both onsite and offsite sheep samples during recent years.

Three large game animals (two mule deer and a pronghorn) were sampled during the second quarter of 2004. There were killed as a result of a vehicular collision. Thyroid, liver, and muscle tissues were sampled when available. Only the naturally occurring radionuclide potassium-40 was measured at concentrations greater than the associated 3s uncertainty values. No human-made radionuclides were detected.

Environmental dosimeter locations are also divided into Boundary and Distant groupings. Boundary exposure rates ranged from a low of 0.29 mR/day to 0.37 mR/day. The overall Boundary average was 0.34 mR/day. The Distant group ranged from 0.27 mR/day to 0.38 mR/day, with an overall average exposure also of 0.33 mR/day. No statistical difference existed between Boundary and Distant locations. All exposure results are consistent with those measured historically.

Quality assurance checks and samples submitted for analysis during the second quarter 2004 met most QA requirements. QA issues arose with method uncertainty and recount accuracy for ¹³¹I measurements in charcoal cartridges and milk, ²⁴¹Am and ⁹⁰Sr in quarterly composites, and gross alpha and tritium in drinking and surface water as measured by criteria established in the ESER Quality Assurance Project Plan. These issues are being resolved with the laboratory to avoid future problems.

No radionuclide in any of the samples taken during the second quarter of 2004 could be directly linked with INEEL activities. Levels of detected radionuclides were no different than values measured at other locations across the United States and consistent with levels measured in the past in this area. Radionuclide concentrations in all of the samples collected and analyzed during the second quarter, 2004 were below guidelines set by both the DOE and the U.S. Environmental Protection Agency (EPA) for protection of the public.

Table E-1       Summary of results for the second quarter of 2004.

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