PNNL-13909 Radionuclide Concentrations in Air on the Hanford Site A Ten-Year Trend Report 1991 Through 2000 B. G. Fritz G. W. Patton May 2002 Prepared for the U.S. Department of Energy under Contract DE-AC06-76RL01830 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor Battelle Memorial Institute, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. 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Patton May 2002 Prepared for the U.S. Department of Energy under Contract DE-AC06-76RL01830 Pacific Northwest National Laboratory Richland, Washington 99352 Summary This report describes the air pathway effects of Hanford Site operations from 1991 through 2000 on local air quality. The end of production of nuclear materials onsite has greatly reduced the atmospheric emissions of radionuclides. This has led to concentrations in air on and around the Hanford Site that are near background levels for most radionuclides. A trend analysis such as this one allows scientists to look at data over a 10-year period and increases their understanding of air emissions. This was done by evaluating trends in air concentrations of selected radionuclides at numerous onsite and offsite locations, comparing measured concentrations to U.S. Department of Energy (DOE) concentration guides, evaluating hypothetical maximally exposed indi- vidual doses over the decade, and evaluating the contribution of individual radionuclides to overall dose. The data for this report come from routine environmental monitoring activities conducted by Surface Environmental Surveillance Project personnel. Routine samples were collected onsite, at the Hanford Site perimeter, in local communities, and at distant locations. Data were used to evaluate concentration gradients, concentration variations over time, and correlations between upwind and downwind locations, onsite emissions, and local meteorology. During the period of this report (1991 through 2000), there were no measured concentrations that exceeded DOE derived concentration guides (Appendix A, Table A.1). The closest any air sample came to the DOE derived concentration guide level was a December 1991 tritium sample that had a measured concentration approximately 5% of the DOE derived concentration guide. The estimated maximally exposed individual doses for the years 1991 through 2000 were thousands of times below the DOE dose limit of 100 mrem per year for a member of the public. The highest estimated maximally exposed individual dose was 0.051 mrem per year in 1994. The air pathway contributions to the maximally exposed individual dose estimates were well below the U.S. Environmental Protection Agency limit of 10 mrem per year. iii Acknowledgments The authors wish to acknowledge R. W. Hanf, T. M. Poston, and John Glissmeyer for their valuable peer review. Launa Morasch provided editorial review and Kathy Neiderhiser and Lila Andor provided text processing. We would also like to acknowledge the contribution of B. M. Gillespie who managed the Surface Environmental Surveillance Project air sampling task from 1996 to 2000. v Contents Summary............................................................................................................................................ iii Acknowledgments.............................................................................................................................. v 1.0 Introduction.............................................................................................................................. 1 2.0 Background Information .......................................................................................................... 1 2.1 Hanford Site Fire.............................................................................................................. 3 3.0 Site Emissions .......................................................................................................................... 4 4.0 Maximally Exposed Individual ................................................................................................ 5 5.0 Air Pathway Surveillance......................................................................................................... 6 5.1 Sample Collection and Analysis Methods ....................................................................... 8 5.2 Sampling Locations.......................................................................................................... 8 6.0 Analytical Results .................................................................................................................... 9 6.1 Gross Alpha..................................................................................................................... 9 6.2 Gross Beta........................................................................................................................ 12 6.3 Tritium............................................................................................................................. 13 6.4 Strontium-90 .................................................................................................................... 15 6.5 Iodine-129........................................................................................................................ 16 6.6 Uranium ........................................................................................................................... 19 6.7 Plutonium......................................................................................................................... 20 6.8 Cesium-137...................................................................................................................... 21 7.0 Dose Contribution from Radionuclides in Air ......................................................................... 23 8.0 Evaluation and Conclusions..................................................................................................... 25 9.0 References................................................................................................................................ 25 vii 10.0 Bibliography............................................................................................................................. 27 Appendix – Data Tables..................................................................................................................... A.1 Figures 1 Hanford Site and Surrounding Areas......................................................................................... 2 2 Annual Onsite Atmospheric Emissions..................................................................................... 5 3 Reported Maximally Exposed Individual Annual Dose Estimate............................................. 7 4 Contribution of Air Pathway to Estimated Maximally Exposed Individual Dose..................... 7 5 Map of Air Sampling Locations ................................................................................................ 10 6 Gross Alpha Concentrations in Air............................................................................................ 12 7 Gross Beta Concentrations in Air.............................................................................................. 13 8 Tritium Concentrations in Air ................................................................................................... 14 9 Annual Average Tritium Concentrations in Air ........................................................................ 14 10 Strontium-90 Concentrations in Air .......................................................................................... 16 11 Quarterly Iodine-129 Concentration in Air ............................................................................... 17 12 Annual Average Iodine-129 Concentrations and Stack Emissions ........................................... 18 13 Annual Iodine-129 Stack Emissions and Estimated Fugitive Emissions .................................. 18 14 Uranium Concentrations in Air ................................................................................................. 20 15 Plutonium Concentrations in Air............................................................................................... 21 16 Plutonium-239/240 Concentrations in Air at Onsite and Perimeter Locations ......................... 22 17 Cesium-137 Concentrations in Air ............................................................................................ 22 18 Concentrations