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A comparison of air samples at ground level and aerial gamma count rates from the response to the Fukushima Dai-Ichi Nuclear Power Plant accident




Sublett, Sarah Miriam, author
Brandl, Alexander, advisor
Biedron, Sandra, committee member
Johnson, Thomas, committee member

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March 11, 2011 will be a day that will never be forgotten in the minds of the thousands of Japanese people whose lives were forever changed by a series of natural disasters, including a 9.0 earthquake and subsequent tsunami that triggered the Fukushima Dai-Ichi Nuclear Power Plant (FDNPP), located on the eastern coast of Japan, to become cripplingly damaged. The FDNPP nuclear accident resulted in the emission of radionuclides into the environment and those released nuclides, specifically 134Cs, 137Cs, and 131I and their measurement by ground and air based means, are the subject of this research project. Within the first few days following the start of the disaster, numerous US federal agencies responded and deployed to Japan to help characterize and measure the release of radionuclides from FDNPP. Over the course of approximately a two-month span, over 500,000 measurements were obtained and analyzed, including air and soil samples and in situ spectra. The core of this research project was to analyze and compare ground air samples to aerial gamma count rate measurements obtained in Fukushima Prefecture within the first two months following the disaster. The results of this project estimate the ground deposition of radionuclides in Fukushima Prefecture, which accounted for 99.4% of the measured aerial net gamma count rate. Another finding of this project is the estimated ground deposition of nuclides based upon aerial gamma count rates in areas where there was measurable ground air contamination was 14.25 times higher than in areas where there was no measurable ground air contamination as determined by the evaluated air samples in this project. Of the samples evaluated in this project, ground deposition averaged 5.4E6 Bq/m2 in areas where there was measurable ground air contamination, versus 3.79E5 Bq/m2 in areas where there was no measurable ground air contamination.


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environmental sampling
ground air samples
health physics
radiation safety


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