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Latest data on doses taken by workers at the Fukushima Daiichi nuclear plant

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The latest data on doses taken by workers at the Fukushima Daiichi nuclear plant are available online at the Ministry of Health, Labor and Social Affairs. They were provided by TEPCO. The company has reset all meters to zero by April 1, 2016.

http://www.mhlw.go.jp/english/topics/2011eq/workers/irpw/ede_170131.pdf

Since that date, and until 31 December 2016, 14,643 workers have been exposed to ionizing radiation at the site of the accidented plant, out of which 13,027 were subcontracted workers (89%). There were 9,484 in December alone, out of which 8,463 were subcontracted workers

The average dose received during these 9 months was 2.14 mSv (2.29 mSv for subcontracted workers and 0.94 mSv for TEPCO employees). The highest dose was 38.76 mSv and a subcontracted worker took it. It should be noted that 93 subcontracted workers have already received a dose higher than 20 mSv. The highest dose taken by a TEPCO employee is 11.63 mSv.

By way of comparison, let us recall that the annual limit dose for the public is 1 mSv per year under normal conditions. For workers, it is 50 mSv per year without exceeding 100 mSv over 5 years. In France, it is strictly 20 mSv per year for workers.

Translated by Hervé courtois from L’ACROnique de Fukushima‘s article : http://fukushima.eu.org/dernieres-donnees-sur-les-doses-prises-par-les-travailleurs-a-la-centrale-de-fukushima-dai-ichi/

February 18, 2017 Posted by | Fukushima 2017 | , , , | Leave a comment

Bioaccessibility of Fukushima-Accident-Derived Cs in Soils and the Contribution of Soil Ingestion to Radiation Doses in Children

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Abstract

Ingestion of contaminated soil is one potential internal exposure pathway in areas contaminated by the Fukushima Daiichi Nuclear Power Plant accident.

Doses from this pathway can be overestimated if the availability of radioactive nuclides in soils for the gastrointestinal tract is not considered.

The concept of bioaccessibility has been adopted to evaluate this availability based on in vitro tests.

This study evaluated the bioaccessibility of radioactive cesium from soils via the physiologically-based extraction test (PBET) and the extractability of those via an extraction test with 1 mol/L of hydrochloric acid (HCl).

The bioaccessibility obtained in the PBET was 5.3% ± 1%, and the extractability in the tests with HCl was 16% ± 3%. The bioaccessibility was strongly correlated with the extractability. This result indicates the possibility that the extractability in HCl can be used as a good predictor of the bioaccessibility with PBET.

In addition, we assessed the doses to children from the ingestion of soil via hand-to-mouth activity based on our PBET results using a probabilistic approach considering the spatial distribution of radioactive cesium in Date City in Fukushima Prefecture and the interindividual differences in the surveyed amounts of soil ingestion in Japan.

The results of this assessment indicate that even if children were to routinely ingest a large amount of soil with relatively high contamination, the radiation doses from this pathway are negligible compared with doses from external exposure owing to deposited radionuclides in Fukushima Prefecture.

http://onlinelibrary.wiley.com/doi/10.1111/risa.12694/full

October 2, 2016 Posted by | Fukushima 2016 | , , , | Leave a comment