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Radiocarbon Releases from the 2011 Fukushima Nuclear Accident.

ABSTRACT: 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 ¹⁴C specific activity varied from 280.4 Bq kg^-1 C in 2010 to 226.0 Bq kg^-1 C in 2015. The elevated ¹⁴C activities in the 2009 and 2010 rings confirmed ¹⁴C 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 ¹⁴C analysis of the 2011 ring indicated ¹⁴C releases during the Fukushima accident. The resulted ¹⁴C activity decreased with increasing distance from the plant. The maximum ¹⁴C activity released during the period of the accident was measured 42.4 Bq kg^-1 C above the natural ambient ¹⁴C background. Our findings indicate that, unlike other Fukushima-derived radionuclides, the ¹⁴C 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 ¹⁴C activities is negligible compared to the dose from natural/nuclear weapons sources.

SUBMITTER: Xu S

PROVIDER: S-EPMC5107918 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Radiocarbon Releases from the 2011 Fukushima Nuclear Accident.

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