Pretreatment technique of environmental sample for radioactivity analysis using supercritical water reaction

超臨界水反応を用いた放射能分析のための環境試料処理技術

永岡 美佳  ; 藤田 博喜; 相田 卓*; Smith, R.*

Nagaoka, Mika; Fujita, Hiroki; Aida, Taku*; Smith, R.*

環境試料中の放射能濃度を測定するには、試料中の有機物分解や目的核種の抽出といった化学分離を行う。しかしながら、従来の化学処理は、化学薬品を使用するため、分析者、分析フードや環境に影響を及ぼす。一方、超臨界水反応は健康や環境へ悪影響をおよぼすことなく有機物が分解できる。そこで超臨界水反応を環境試料中の放射能濃度分析への適用を検討する。本研究では、環境試料における有機物やSr濃度について、超臨界水反応の前後で比較を行った。有機物は、高い温度、長い反応時間でより分解された、しかし、Srは反応後溶液中に抽出されなかった。

Radioactivity concentration in environmental sample such as leaf, seaweed has been measured through chemical separation with organic matter decomposition and extraction of target element. However, the usual chemical treatment could affect worker's health, chemical hood and surrounding environment by usage of chemical regent. On the other hand, supercritical water reaction could decompose organic matter without health and environmental hazard caused by the regent. Therefore, we have tried to apply the supercritical water reaction to radioactivity analysis of environmental samples. In this research, organic matter content and strontium concentration in environmental sample were compared with between before and after the reaction. The organic matters were highly decomposed with the water reaction at higher temperature and for longer reaction time. However the strontium was not extracted into solution after the reaction.