Conference Paper Simultaneous determination of radiocesium and Pu isotopes in river suspended particles

Cao, Liguo  ,  Zheng, Jian  ,  Tsukada, Hirofumi  ,  Pan, Shaoming  ,  Tagami, Keiko  ,  Uchida, Shigeo

Due to radioactive material releases from the Fukushima Dai-ichi Nuclear Power Plant accident, long-term monitoring and assessment of radiocesium (135Cs and 137Cs) and Pu isotopes (239Pu and 240Pu) in river suspended particles are required to investigate the fate of these long-lived radioisotopes. Sampling of suspended particles to obtain enough amounts for determination of these isotopes by conventional methods is technically difficult and thus it is expensive in river environments. In the present work, therefore, we developed a simultaneous determination of radiocesium and Pu isotopes in suspended particles with small sample size (1-2 g) to reduce the sampling amounts. Specifically, radiocesium and Pu were sequentially pre-concentrated using ammonium molybdophosphate and ferric hydroxide co-precipitation, respectively. After the two-stage ion-exchange chromatography separations, radiocesium and Pu isotopes were measured by ICP-MS/MS and SF-ICP-MS, respectively. The interfering elements, i.e., U (238U1H+ and 238U2H+ for 239Pu and 240Pu, respectively) and Ba (135Ba+ and 137Ba+ for 135Cs and 137Cs, respectively), were almost completely removed, with high decontamination factors of 1-8 × 106 and 1 × 104, respectively. IAEA-soil-6 and IAEA-375 were used for method validation, and the obtained 135Cs/137Cs and 240Pu/239Pu atom ratios, and 239+240Pu activities showed good agreements with the certified/information values.

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