Direct measurement of Cs in Cs adsorbent used for water decontamination by laser-ablation ICP-MS

Asai, Shiho*; Ohata, Masaki*; Hanzawa, Yukiko  ; Horita, Takuma ; Yomogida, Takumi   ; Kitatsuji, Yoshihiro  

A large amount of spent Cs adsorbents used for decontaminating water in Fukushima Daiichi Nuclear Power Station are stored in the site. To dispose them safely, the estimation of Cs activity along with that of Cs is indispensable. Cs is generally measured by ICP-MS, which required the sample to be prepared in liquid form and thus the elution of Cs from the Cs adsorbents is essential. However, this approach suffers from the high radiation dose from Cs. In this study, we quantified Cs in a Cs adsorbent using the Cs/Cs ratio obtained by LA-ICP-MS and Cs radioactivity obtained by gamma spectrometry. To evaluate the applicability, we employed a Cs -containing water sample to prepare a model spent Cs adsorbent with a certified Cs activity. The resulting Cs activity of 0.36 Bq calculated by Cs /Cs ratio of 0.41 0.02 and Cs activity agreed well with that of the originally determined Cs activity in the model spent Cs adsorbent, demonstrating that the proposed technique has high validity to Cs determination of a real sample.