Quarterly Reports of Analytical Results for the CEMP Air and TLD Sampling Network
The CEMP air-sampling network is designed to monitor and collect radioactive airborne particles from NNSS and non-NNSS related activities, as well as background environmental sources. These reports are provided to the station managers as a summary of the results from the analysis of the air samples collected as part of the Community Environmental Monitoring Project.
The CEMP air sampling network is comprised of 29 continuously operating environmental sampling stations. A total of 27 stations are equipped with a low volume air sampler/totalizer configuration to collect particulate radionuclides on glass fiber filter paper. It is important to note that prior to the fourth quarter of CY2008 the air filters were collected on a weekly basis with the samplers calibrated monthly by DRI to maintain a collection rate of 2.0 cfm (@STP). Beginning with the fourth quarter of CY2008, the air sampling program changed to a bi-weekly collection schedule with the samplers calibrated at a flow rate 1.75 cfm (@STP). All relevant information such as collection times, variation in flow rate, actual flow volumes, power outages, and other information documenting the integrity of the sample are recorded by the station managers. This allows for the proper interpretation of the analytical results. The air filters are analyzed by a commercial laboratory for gross alpha/beta activity as well as by high-resolution gamma spectroscopy. The filters are composited on a quarterly basis for gamma spectroscopy analysis only after the gross alpha/beta analyses have been completed.
The principle reporting unit used in the U.S. for the measurement of radioactivity in the atmospheric environment is pCi/m3 (picocuries per meter cubic meter). DRI receives its data from the lab as picocuries per filter, which is then recalculated as microcuries per milliliter based on the information provided by the station managers as well as monthly calibration results. This is the notation used for DRI internal databases and annual reports to DOE/NNSA. For the ease in constructing the tables contained in these reports, as well as hopefully the ease of comparison among stations and previous results, the units of pCi/m3 are used. The data for the environmental TLD is reported in milliroentgens (mR).
In addition to the air particulate sampling results presented in these reports, CEMP stations are also equipped with environmental thermoluminescent dosimeters (TLDs). These devices measure the cumulative gamma radiation dose at the station on a quarterly basis, and closely approximate the dose a resident could have potentially received in their community from natural and non-natural sources. The data for the environmental TLD is reported in milliroentgens (mR).
To date, results of analyses obtained from the CEMP air sampling and TLD network have shown no measurable evidence at CEMP station locations of offsite impacts from radionuclides originating on the Nevada Nuclear Security Site. Activity observed in gross alpha/beta, gamma spectroscopy and TLD analyses are within the range of results found in other communities of the United States that are not adjacent to man-made radiation sources.