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Executive Summary

Some human-made radionuclides were detected in samples collected during the second quarter of 2018. 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 second 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, April 1 through June 30, 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
    • Surface and drinking water
    • Milk
    • Alfalfa
    • Environmental radiation measurements using OSLDs

Table E-1 Summary of results for the Second 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, with the exception of the gross alpha activity for the second quarter and the month of April. 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. Statistical differences do not appear to be linked to INL Site activities.

Particulate Filters Quarterly Composite

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

No human-made gamma-emitting radionuclides were detected in any of the second quarter composite air samples. Americium-241, 238Pu and 239/240Pu, human-made alpha-emitting radionuclides, were detected above 3s in the composite sample from Van Buren Boulevard. The concentrations of the plutonium isotopes were the maximum recorded in the past ten years by ESER. The 241Am result was the second highest measured since 2009. All detections, however, are well below the DCSs and do not represent a public health concern. Potential sources are being investigated.

Strontium-90, a human-made beta-emitting radionuclide was measured in the composite collected from Arco. The result was within those detected historically, from 2009 through 2017, and far below the DCS. It is most likely the result of resuspension of soil contaminated with fallout from past nuclear weapons testing.

Charcoal Cartridge


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

Atmospheric Moisture



Ten of seventeen 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 28 samples were collected. All 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 was detected in two of ten drinking water samples and in one of three surface water samples.  Gross beta was detected in nine of ten drinking water samples and in all surface water samples. All concentrations were generally similar from previous results. Tritium was detected in four drinking water and surface water samples. Concentrations were similar to those measured historically in drinking and surface water and well below the DCS for tritium in drinking water.

Big Lost River


Gross alpha, gross beta, tritium

The BLR was sampled twice in the second quarter. Gross alpha activity was detected in 10 of 14 samples (including the control). Gross beta activity was detected 12 of 14 samples. The concentrations were generally similar to previous results. Tritium was also detected in nine samples. Concentrations were similar to those found in atmospheric moisture and precipitation samples and were consistent with previous years. The tritium results were below the DCS for drinking water.



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

Forty milk samples were collected at seven locations (including the offsite control sample from Colorado). No gamma emitting radionuclides of concern were detected.

Strontium-90 was detected in three of seven samples. All were approximately the same concentration (including the offsite control from Colorado) indicating the INL Site is not the source. Tritium was detected in five samples at levels similar to previous measurements and to precipitation.



Gamma-emitting radionuclides, strontium-90

No human-made gamma-emitting radionuclides were found in any of the four samples (including a duplicate) collected this year.  Strontium-90 was found in one of three samples analyzed. The value was within measurements made in previous years.

Environmental Dosimeters

Environmental radiation

Ionizing radiation exposure

The average measurements over the six-month period were 0.32 mrem/day at Boundary and 0.33 mrem/day at Distant locations. The results are consistent with past results.

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