Journal Article Strontium-90 activity concentration in soil samples from the exclusion zone of the Fukushima daiichi nuclear power plant

Sahoo, S.K.  ,  Kavasi, N.  ,  Sorimachi, A.  ,  Arae, H.  ,  Tokonami, S.  ,  Mietelski, J.W.  ,  Lokas, E.  ,  Yoshida, S.

23925 ( 6 )  , pp.23925-1 - 23925-10 , 2016-04 , Nature Publishing Group
The radioactive fission product 90Sr has a long biological half-life (˜18 y) in the human body. Due to its chemical similarity to calcium it accumulates in bones and irradiates the bone marrow, causing its high radio-toxicity. Assessing 90Sr is therefore extremely important in case of a nuclear disaster. In this work 16 soil samples were collected from the exclusion zone (<30 km) of the earthquake-damaged Fukushima Daiichi nuclear power plant, to measure 90Sr activity concentration using liquid scintillation counting. 137Cs activity concentration was also measured with gamma-spectroscopy in order to investigate correlation with 90Sr. The 90Sr activity concentrations ranged from 3.0 ± 0.3 to 23.3 ± 1.5 Bq kg−1 while the 137Cs from 0.7 ± 0.1 to 110.8 ± 0.3 kBq kg−1. The fact that radioactive contamination originated from the Fukushima nuclear accident was obvious due to the presence of 134Cs. However, 90Sr contamination was not confirmed in all samples although detectable amounts of 90Sr can be expected in Japanese soils, as a background, stemming from global fallout due to the atmospheric nuclear weapon tests. Correlation analysis between 90Sr and 137Cs activity concentrations provides a potentially powerful tool to discriminate background 90Sr level from its Fukushima contribution.

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