Determination of radiostrontium released from Fukushima Daiichi Nuclear Power Plant through extraction chromatography and liquid scintillation counting

Two soil samples were collected on April 18-20, 2011 at Namie town and Tomioka town, which are located 26 km northwest and 11 km south of the Fukushima Daiichi Nuclear Power Plant, respectively. A 0-1 cm soil layer was used for analysis to determine the presence of radiostrontium. The soil was ashed, acid-digested, and strontium was separated from interference with use of an extraction chromatography resin (Sr resin, Eichrom Technologies). The isolation and purification of strontium from matrix components can be completed in 12 h. After 2 weeks for ingrowth of ⁹⁰Y, measurements of a beta-ray of ⁹⁰Y and ⁸⁹⁺⁹⁰Sr were conducted with a low-background liquid-scintillation counter for 1200 min. The concentration of ⁹⁰Sr was determined to be 57.4 ± 1.0 and 10.1 ± 0.4 Bq kg^-1 for Namie town and Tomioka town, respectively. ⁸⁹Sr was not detected in either sample. The extraction chromatography method was successfully applied to determine the level of radiostrontium in the contaminated soil. When 2 g of soil is used, the detection limit of ⁹⁰Sr is evaluated to be 2.7 Bq kg^-1 under a chemical yield of strontium of 70%. (author)