RadNet Sampling and Analyses Schedules

Under normal conditions, RadNet air monitors operate continuously and samples of air, precipitation and drinking water are analyzed on a routine schedule. In a radiological emergency, EPA may deploy teams to conduct air monitoring and environmental sampling. Learn about EPA’s role in radiological emergency response.

Medium Sampling Frequency Testing Frequency
Air Filters Continuous (real time) Continuous (real time)
Precipitation As rainfall, snow or sleet occurs Monthly analysis of a composite sample
Drinking Water Quarterly Quarterly
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Routine Sample Analyses

Medium Analyses
Air Filters
Individual Samples
  • A grossCombined or total sum (as in “Gross Beta”). beta analysis is performed at NAREL.
  • If the beta concentration is greater than 1 pCi/m3, gamma spectroscopy The analysis of photons (X-ray or Gamma) emitted from radioactive atoms as they undergo transformations to more stable atoms. The RadNet Fixed (Stationary) Monitors contain a detector system that provides information on the quantity and energy of photons emitted by radioactive material captured on the air filter (and the surroundings). These data may then be used by trained spectroscopists to identify the radioactive atoms that are emitting the gamma radiation. and possibly other analyses are performed.

Annual Composite Sample

  • Gamma analysis is performed on all annual composite samples.
  • Isotopic plutonium (Pu) and uranium (U) analyses are performed on composite samples from one-fourth of the stations on a four-year rotating schedule.
Precipitation
Monthly Composite Samples
  • GammaGamma rays come from many different radioactive elements, both natural and man-made. Gamma rays can penetrate several feet of concrete or a few inches of lead. Gamma rays can pose a serious health threat inside and outside the body and can be lethal depending on the amount received. Scientists use the properties of gamma rays to identify radioactive elements.analyses are performed on all composite samples.
Drinking Water
Individual Samples
  • Tritium (H-3) analysis is performed on each quarterly sample received. 
  • Iodine-131 (I-131) analyses are performed on one sample per station per year.
Composite Samples
  • Gross alpha, beta and gamma are performed on all composite samples.
  • Strontium-90 (Sr-90) is performed on composite samples from one-fourth of the stations on a four-year rotating schedule.
  • Radium-226 if the gross alpha exceeds 2 pCi/L.
  • Radium-228 if the Radium-226 results are between 3 and 5 pCi/L.
  • Isotopic uranium and plutonium if gross alpha exceeds 2 pCi/L.

RadNet Air Filter Inquiries

A RadNet air filter inquiry is initiated when there is potential for a release of radioactive materials to the air that could result in the presence of airborne radionuclides at low concentrations, or if low concentrations of radionuclides have been detected in the US or by an international agency. View the RadNet Air Filter Inquiry Log.

Emergency Schedule

RadNet sampling and analysis are particularly useful when an event such as an explosion or fire sends significant levels of radionuclides into the air. Results of real-time data acquisition and subsequent sample analysis can provide critical information on the identity and concentration of radionuclides in air, precipitation and drinking water. Data from RadNet are useful in dose assessments, as health physicists estimate the immediate and long-term environmental and public health effects.

Learn how RadNet was used during and after Chernobyl and other radiological incidents in the report, Historical Uses of RadNet Data (pdf) (564.16 K). 

RadNet

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Last updated on February 7, 2025