Abstract: DEVELOPMENT OF SIMULATED ~(131)Ｉ STANDARD SOURCEDu Hongshan;Li Junlan;Yan Sujuan;Sun Naiyao;Guo Chunsheng;Yao Linong(China Institute of Atomic Energy, Beijing 102413)Abstract:A method for preparing simulated 131Ｉ standard source with mixed 133Ba and 137Cs is presented. Aseries of experimental conditions are investigated such as the choice of the optimum ratio of t33fo toabCs, the structure and compoSition of simulated 131I standard source, the determination of the support, absorb material and its thickness and so on. The procedure for prefering simulated 131I standard sourceis set up. TeSt resultS show that the simulated 13l standard source obtained by the methed fully meetSthe requirements of the radioactive standard.Keywords: ~(131)Ｉ; ~(133)Ba;~(137)Cs;simulated ~(131)Ｉ;standard source