This is the first PNNL Site report to include LSLII and RTL facilities, as incorporated into the Radioactive Air Emissions License-05. This report documents radionuclide air emissions that result in the highest effective dose equivalent (EDE) to an offsite member of the public, referred to as the maximally exposed individual (MEI). The report has been prepared in compliance with the Code of Federal Regulations (CFR), Title 40, Protection of the Environment, Part 61, National Emission Standards for Hazardous Air Pollutants (NESHAP), Subpart H, "National Emission Standards for Emissions of Radionuclides Other than Radon from Department of Energy Facilities" and Washington Administrative Code (WAC) Chapter 246-247, "Radiation Protection-Air Emissions." Federal regulations in 40 CFR 61, Subpart H require the measurement and reporting of radionuclides emitted from DOE facilities and the resulting offsite dose from those emissions. Those regulations impose a standard of 10 mrem/yr EDE, which is not to be exceeded. Washington State adopted the 40 CFR 61 standard of 10 mrem/yr EDE into its regulations that require the calculation and reporting of the EDE to the MEI from both point source emissions and from any fugitive source emissions of radionuclides. WAC 246-247 further requires the reporting of radionuclide emissions, including radon, from all PNNL Site sources. The Clean Air Act Amendments of 1989 revised the NESHAP regulations (i.e., 40 CFR 61, Subpart H) to govern emissions of radionuclides from DOE facilities. Those regulations are intended for the measurement of point source emissions but are inclusive of fugitive emissions with regard to complying with the dose standard. The dose to the PNNL Site MEI due to routine major and minor point source emissions in 2012 from PNNL Site sources is 9E-06 mrem (9E-08 mSv) EDE. The dose from fugitive emissions (i.e., unmonitored sources) is 1E-7 mrem (1E-9 mSv) EDE. The dose from radon emissions is 2E-6 mrem (2E-08 mSv) EDE. No nonroutine emissions occurred in 2012. The total radiological dose for 2012 to the MEI from all PNNL Site radionuclide emissions, including fugitive emissions and radon, is 1E-5 mrem (1E-7 mSv) EDE, or 100,000 times smaller than the federal and state standard of 10 mrem/yr, to which the PNNL Site is in compliance.
Since August 1989, 222Rn groundwater samples from across the state of Arizona have been collected and analyzed using liquid scintillation. Of the 253 specimens acquired, 65% have 222Rn concentrations above 11 Bq L-1 (300 pCi L-1), while 16% have 222Rn activities over 37 Bq L-1 (1,000 pCi L-1). The geometric mean 222Rn concentration for all the wells tested is 13 Bq L-1 x divided by 4; the arithmetic mean is 37 +/- 122 Bq L-1. Using the geometric mean, it is estimated that an additional tracheobronchial lung dose equivalent of 0.19 mSv y-1 x divided by 13.9 is delivered to Arizona residents from the well water to home pathway.
SummaryThis study draws a relationship between filter mass loading, percent loss using the mass loading data collected, and previous studies of self-absorption. The mass loading consists of particulate dust, radioactive particulates, and filter material. A study by Higby [1984] calculated a minimum burial depth for an alpha particle to be lost due to absorption (100% loss) of about 3. . Mass loadings in this latter study included dust loading plus the mass of the front layer of filter. This study examined light dust loadings (averaging about 0.1 mg cm -2 ) on filter material and compared this with other literature data to estimate losses at typical mass loadings on filters from PNNL sampled exhaust sites.During an 18-month period, 116 samples were collected and analyzed from 8 different building stacks. Under normal operating conditions at the stacks monitored by Effluent Management, the mass loading of sample filters averages 0.09 + 0.12 (2σ) mg cm -2 (excluding negative values and outliers) and ranges from 0 mg cm -2 to 0.24 mg cm -2 . This study presents two different methods of relating percent loss due to selfabsorption to filter mass loading: exponential and linear relationships based on data from Luetzelschwab et al. [2000] and Higby [1984]. In general, samples have losses of less than 19% using the conservative exponential model and less than 7% using the linear model; therefore, a correction factor of 0.85 remains conservative.For higher accuracy, the Effluent Management group recommends that each filter be weighed before and after installation on the sampling system. Having tare weights and gross weights allow the mass loading of each filter and any applicable correction factors to be determined on a case-by-case basis.
Since the mid-1980's the Pacific Northwest National Laboratory (PNNL) has used a value of 0.85 as a correction factor for the self absorption of activity for particulate radioactive air samples collected from building exhaust for environmental monitoring. More recently, an effort was made to evaluate the current particulate radioactive air sample filters (Versapor 3000, 47-mm diameter) used at PNNL for self absorption effects. There were two methods used to characterize the samples. Sixty samples were selected from the archive for acid digestion to compare the radioactivity measured by direct gas-flow proportional counting of filters to the results obtained after acid digestion of the filter and counting again by gas-flow proportional detection. Thirty different sample filters were selected for visible light microscopy to evaluate filter loading and particulate characteristics. Mass-loading effects were also considered. Large error is associated with the sample filter analysis comparison and subsequently with the estimation of the absorption factor resulting in an inadequate method to estimate losses from self-absorption in the sample filter. The mass loading on the sample filter as determined after digestion and drying was approximately 0.08 mg cm; however, this value may not represent the total filter mass loading given that there may be undetermined losses associated with the digestion process. While it is difficult to determine how much material is imbedded in the filter, observations from the microscopy analysis indicate that the vast majority of the particles remain on the top of the filter. In comparing the results obtained, the continued use of 0.85 as a conservative correction factor is recommended.
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