Abstract: PREPARATION OF CdSe (79Se) AND ITS APPLICATIONLi Chunsheng Guo Jingru Jiang Songsheng Li Daming(China Institute of Atomic Energy,P.O.Box 275(26),Beijing 102413)ABSTRACTThrough twostep chemical reactions,CdSe is synthesized using element Se as starting material.The chemical composition and crystal structure of CdSe prepared are determined with chemical analysis and Xray diffraction method.79Se separated from high level radioactive liquid waste is used for preparing CdSe(79Se).As sample material,CdSe(79Se) has been used successfully in AMS for the determination of 79Se halflife.Key words 79Se CdSe Accelerator mass spectrometry(AMS)