@misc{oai:repo.qst.go.jp:00084110,
 author = {Kasar, Sharayu and Kumar Sahoo, Sarata and Aono, Tatsuo and Kasar, Sharayu and Sahoo, Sarata and Tatsuo, Aono},
 month = {Dec},
 note = {Fukushima dai-ichi nuclear power station (FDNPS) accident in March 2011 released huge amounts of volatile fission products such as 129mTe, 131I, 134Cs, and 137Cs with traces of U, Pu, Am, Cm, Np nuclides in the terrestrial area in the east Japan (Povinec et al., 2013). From the viewpoint of radiation protection, it is crucial to obtain sufficient data on U and Pu radioisotopes. Measurement of 236U/238U and 238Pu/137Cs ratios in soil could be used as tracers to identify source of contamination due to nuclear accident. Furthermore, concentrations of 236U and 238Pu will help to improve internal dose estimation.
Therefore, Fukushima soils were selected based on 137Cs concentration. The 137Cs activity concentration ranged from 150 to 5000 Bq/g in soils collected from Okuma town within <5 km distance from FDNPS.
Abundances of 236U and 238Pu as well as 236U/238U and 238Pu/137Cs isotope ratios were measured in the present work. Thermal ionization mass spectrometry (TIMS) was used to measure isotope ratio of 236U/238U whereas alpha spectrometry was used for 238Pu activity concentration determination. 
236U/238U ratio in Japanese soils based on global fallout ranged between (1.9~11.0) × 10e-8 (Kasar et al., 2021). 236U/238U ratio in Fukushima soils varied from ((0.6–20.0) × 10e-8), which showed relatively a higher value than global fallout. The abundances of 236U in these soils varied in the range of ((2.0-20.0) × 10-5) Bq/kg. This may be due to the mixing effect of global fallout and FDNPS accident. 238Pu activity concentration was found to be in the range of 0.006-0.1 Bq/kg. The highest activity concentration of 238Pu in Fukushima soil has been reported as 0.092 Bg/kg (Kierepko et al., 2019). 238Pu activity concentration values showed heterogeneous distribution of actinides in environment. The linear correlation of 238Pu activity concentration with 137Cs  which may support the release of actinides during accident.
The behaviour of Cs, U and Pu isotopes in Fukushima soils and their comparison with results of Chernobyl soils will be presented in conference.This study was supported by Fukushima Prefecture related to Research and Development in Radiological Sciences. Authors are thankful to Drs. N. Kavasi, Y. Omori and A. Sorimachi for samples collection., The 6th International Conference on Environmental Radioactivity (ENVIRA 2021)},
 title = {236U and 238Pu concentrations in soils affected by Fukushima Dai-ichi Nuclear Power Station accident},
 year = {2021}
}