Radiocarbon Releases from the 2011 Fukushima Nuclear Accident

Radiocarbon activities were measured in annual tree rings for the years 2009 to 2015 from Japanese cedar trees ( Cryptomeria japonica ) collected at six sites ranging from 2.5–38 km northwest and north of the Fukushima Dai-ichi nuclear power plant. The 14 C specific activity varied from 280.4 Bq kg...

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Bibliographic Details
Published in:	Scientific reports Vol. 6; no. 1; p. 36947
Main Authors:	Xu, Sheng, Cook, Gordon T., Cresswell, Alan J., Dunbar, Elaine, Freeman, Stewart P. H. T., Hou, Xiaolin, Jacobsson, Piotr, Kinch, Helen R., Naysmith, Philip, Sanderson, David C. W., Tripney, Brian G.
Format:	Journal Article
Language:	English
Published:	London Nature Publishing Group UK 14-11-2016 Nature Publishing Group
Subjects:	639/638/11/296 704/172/169/824 Carbon Radioisotopes - analysis Cryptomeria japonica Fukushima Nuclear Accident Humanities and Social Sciences Japan Local population multidisciplinary Nuclear accidents & safety Nuclear power plants Nuclear weapons Radiation Monitoring - methods Radioisotopes Reactors Science Soil Pollutants, Radioactive - analysis Wood - chemistry
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Summary:	Radiocarbon activities were measured in annual tree rings for the years 2009 to 2015 from Japanese cedar trees ( Cryptomeria japonica ) collected at six sites ranging from 2.5–38 km northwest and north of the Fukushima Dai-ichi nuclear power plant. The 14 C specific activity varied from 280.4 Bq kg −1 C in 2010 to 226.0 Bq kg −1 C in 2015. The elevated 14 C activities in the 2009 and 2010 rings confirmed 14 C discharges during routine reactor operations, whereas those activities that were indistinguishable from background in 2012–2015 coincided with the permanent shutdown of the reactors after the accident in 2011. High-resolution 14 C analysis of the 2011 ring indicated 14 C releases during the Fukushima accident. The resulted 14 C activity decreased with increasing distance from the plant. The maximum 14 C activity released during the period of the accident was measured 42.4 Bq kg −1 C above the natural ambient 14 C background. Our findings indicate that, unlike other Fukushima-derived radionuclides, the 14 C released during the accident is indistinguishable from ambient background beyond the local environment (~30 km from the plant). Furthermore, the resulting dose to the local population from the excess 14 C activities is negligible compared to the dose from natural/nuclear weapons sources.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	2045-2322 2045-2322
DOI:	10.1038/srep36947