Background: Instrument neutron activation analysis is a nondestructive analytic method. Some elements after irradiation produce short half-life radio-nuclides (<60 s)

and others produce both long-lived and short-lived nuclides. For these short-lived nuclides

the single measurement has big error. Purpose: In order to reduce the error

cyclic neutron activation analysis can be used to improve the sensitivity. Methods: A device was designed to be connected to the sample transporter

detector and irradiation pipeline in the reactor

which can automatically control the irradiation time and counting time. According to the nuclear parameters of certain elements

irradiation time and counting time and cycle times were determined by experiment. Cyclic activation analysis method was established at the mini-reactor. Results: This paper studied cyclic activation analysis conditions of 17 kinds of element

and applied to the determination of actual samples. Cyclic epithermal neutron activation analysis (CENAA) method was discussed too. By the analysis of national standard reference materials

the reliability of this method was confirmed. Conclusion: Cyclic neutron activation analysis (CNAA) is an effective analytic method for only short life nuclide elements. For both short and long lived nuclides of elements

the cyclic activation analysis method can make the analytical cycle shorten

from a few days or several weeks to within a few minutes. Cyclic activation analysis has the advantages of high sensitivity

and its precision and accuracy are better than single short irradiation activation analysis.Cited