Abstract: MEASUREMENT OF FISSION YIELD OF 135Cs FROM THERMAL NEUTRON INDUCED FISSION OF 235U BY NEUTRON ACTIVATION ANALYSISZhang Shengdong Guo Jingru Cui Anzhi Li Daming Zhang Shulan Sun Hongqing Yang Yi Li Hui(China Institute of Atomic Energy,P.O.Box 275(26),Beijing 102413)ABSTRACTThe fission yield of 135Cs in the thermal neutron fission of 235U is measured accurately by a neutron activation analysis in which the fission fragments are recoiled to a Al catcher.The preparation of 235U targets and the recoilcatcher assembly,determination of neutron flux by Au flux monitor,radiochemical separation and detection of 136Cs and 137Cs are studied.The fission yield of 135Cs is obtained to be (6.34±0.46)% with the fission yield of 137Cs as standard.Keywords Neutron activation analysis Recoilcatch 135Cs Fission yield