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INL Site

Executive Summary

Some human-made radionuclides were detected in samples collected during the fourth quarter of 2018. With the exception of waterfowl, none of the radionuclides detected in samples collected during the fourth quarter of 2018 could be directly linked with INL Site activities.  All detected radionuclide concentrations were well below standards set by the U.S. Department of Energy (DOE) and regulatory standards established by the U.S. Environmental Protection Agency (EPA) for protection of the public. 

This report for the fourth quarter of 2018 contains results from the Environmental Surveillance, Education, and Research (ESER) Program’s monitoring of the Department of Energy’s Idaho National Laboratory (INL) Site’s offsite environment, October 1 through December 31, 2018. All sample types (media) and the sampling schedule followed during 2018 are listed in Appendix A. This report contains results for the following sample types:

    • Air, including particulate air filters, charcoal cartridges, and atmospheric moisture
    • Precipitation
    • Drinking and surface water
    • Milk
    • Waterfowl
    • TLDs
    • OSLDs

Table E-1 Summary of results for the Fourth Quarter of 2018.


Sample Type




Particulate Filters

Gross alpha, gross beta

There were no statistically significant differences in monthly and quarterly gross alpha and gross beta concentrations measured at Distant, Boundary, and INL Site sampling locations. No result exceeded results for the past ten years or the Derived Concentration Standard (DCS) for plutonium-239 (an alpha-emitting radionuclide) or strontium-90 (a beta-emitting radionuclide) in air.

Particulate Filters Quarterly Composite

Gamma-emitting radionuclides, 90Sr, actinides (americium and plutonium)

No human-made gamma-emitting radionuclides were detected in any of the fourth quarter composite air samples.
Americium-241, 238Pu and 239/240Pu, human-made alpha-emitting radionuclides, were not detected in any composited air sample, nor was strontium-90, a human-made beta-emitting radionuclides.

Charcoal Cartridge


Iodine-131 was not detected in any of the 26 batches counted during the quarter.

Atmospheric Moisture



Five of fifteen results showed tritium concentrations greater than the 3s uncertainty during the quarter. No sample result exceeded results for the past ten years or the DCS for tritium in air.




A total of 17 samples were collected during the fourth quarter. Five of the tritium results were greater than the 3s uncertainty. All results were within the range previously measured in the past ten years and were consistent with those reported across the region by the Environmental Protection Agency.

Drinking/Surface Water


Gross alpha, gross beta, tritium

Gross alpha activity was detected in four drinking water samples and one surface water sample. Gross beta activity was detected in seven of the nine drinking water and all four surface water samples. Values were consistent with natural levels of gross beta radioactivity in the Snake River Plain Aquifer. Tritium was not detected in any drinking water but was found in one surface water sample. Results were similar to previous results and those in precipitation.




Iodine-131, other gamma-emitting radionuclides, strontium-90

Thirty-nine milk samples were collected at seven locations (including the offsite control sample from Colorado). No gamma emitting radionuclides of concern or tritium were detected. Strontium-90 was not detected in any samples. This radionuclide is sometimes detected, with similar concentrations among locations (including the offsite control from Colorado) indicating the INL Site has not been the source. Tritium was detected in one samples at a level similar to previous measurements and to precipitation.




Gamma-emitting radionuclides, 90Sr, actinides (americium and plutonium)

Four human-made radionuclides were detected in some ducks at levels suggesting that they were ingested from ATR effluent ponds. The maximum dose from eating the edible tissue of a contaminated duck was estimated to be 0.016 mrem/year, lower than in the previous year.

Environmental Dosimeters

Environmental radiation

External radioactivity

Measurements of environmental radiation made using optically-stimulated luminescent dosimeters (OSLDs) show similar measurements at Distant locations and Boundary locations. The average of all measurements is about 67 mrem for the quarter. Results of a study of thermoluminescent dosimeters (TLDs) and OSLDs are discussed. 



Radiation in Our World

Radiation has always been a part of the natural environment in the form of cosmic radiation, cosmogenic radionuclides [carbon-14 (14C), Beryllium-7 (7Be), and tritium (3H)], and naturally occurring radionuclides, such as potassium-40 (40K), and the thorium, uranium, and actinium series radionuclides which have very long half lives. Additionally, human-made radionuclides were distributed throughout the world beginning in the early 1940s. Atmospheric testing of nuclear weapons from 1945 through 1980 and nuclear power plant accidents, such as the Chernobyl accident in the former Soviet Union during 1986, have resulted in fallout of detectable radionuclides around the world. This natural and manmade global fallout radioactivity is referred to as background radiation. MORE

Radiation Exposure and Dose

The primary concern regarding radioactivity is the amount of energy deposited by particles or gamma radiation to the surrounding environment. It is possible that the energy from radiation may damage living tissue. When radiation interacts with the atoms of a given substance, it can alter the number of electrons associated with those atoms (usually removing orbital electrons). This is called ionization. MORE