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Radioactive dust from nuclear work found in workers’ homes and beyond

Microanalysis of Particle-Based Uranium, Thorium, and Plutonium in Nuclear Workers’ House Dust Mary Ann Liebert Publishers , Marco Kaltofen

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Abstract

Scanning electron microscopy and energy dispersive X-ray analysis (SEM/EDS), a technique not routinely used to detect radiation, was used to identify radioactive particulate matter in house and environmental dust. The study focused on elements that are necessarily radioactive, including thorium, plutonium, americium, and uranium. Seventy-nine dust and 31 soil and sediment samples were collected from the Hanford Nuclear Reservation, Los Alamos National Laboratory, the former Rocky Flats Plant in Colorado, and from homes of workers or abutters of these nuclear facilities. Dusts containing percent levels of uranium, plutonium, americium, and both mineral and metallic thorium were detected outside of radiation-controlled areas. These radioactive dusts are a potential source of internal radiation exposure to nuclear site workers, or to their families via secondary contamination. Uranium and thorium-containing particles were fingerprinted as either natural minerals or processed industrial particles, based on elemental composition of the microparticles. Activities of individual uranium-, thorium-, or plutonium-bearing dust particles varied by five orders of magnitude, ranging from <0.005 mBq (millibecquerel) to 2,270 mBq. Hanford workplace dusts also had up to 564 ± 24 Bq/kg of137Cs. SEM/EDS techniques reliably detected environmental radioactivity in samples that had barely detectable results by gamma spectrometry. The technique was able to definitively show that thorium, plutonium, and uranium from nuclear facilities could be found in general population settings outside of radiation protection zones…………..

Conclusions

Dusts in this study contained radioactive particles of uranium, thorium, plutonium, and americium. This study found monazites, uranium mineral, and Th-P-REE particles that were likely of natural origin and industrial (plutonium-containing, metallic or metal oxide) radioactive microparticles.

Dust in the homes of workers and neighbors of Hanford, Los Alamos, and the former Rocky Flats nuclear facility contained radioactive microparticles connected to these sites. This creates potential radiation exposures outside of radiological protection zones. Given the small respirable size of these radioactive microparticles, they are a potential source of internal exposure from inhalation or ingestion.

SEM/EDS coupled with gamma spectroscopy and autoradiography proved a useful technique for distinguishing the origins of particulate-based radioisotopes that have both industrial and natural sources. Micron-sized radioactive industrial particles were detected in samples that had gross activity levels that were near background. This is an especially useful tool for nuclides, such as uranium and thorium, which have both natural and industrial sources. SEM/EDS distinguished metallic (more likely industrial) versus mineral (more likely natural or mining-related) forms of these elements by determining the complete elemental composition of each particle. https://www.liebertpub.com/doi/10.1089/ees.2018.0036?utm_source=sfmc&utm_medium=email&utm_campaign=EES+FP+Feb+8+2019&d=2%2F8%2F2019&mcid=83805056&

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February 12, 2019 - Posted by | environment, USA

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