Researches On Method Of Radioactivity Determination In Aquatic Products

This eassay is focus on the researches on method of radioactivity determination in aquatic prducts by means of γ-ray spectrometry.In the study, some common local export aquatic products are used as samples.Cs-137 is used as the object of the study. By means of the method of instumental constant and the method of detection efficiency, the radioactivity of the samples were monitored,the result of the determination was analysed,and the method of determination was also filtrated.The purpose of the study is to find out the best method of radioactivity determination in aquatic prducts through the experiments of the methods.The experiments of the methods mainly include:the preparation of the samples,energy calibration,the determination of instrumental constant,efficiency calibration,and the determination of radioactivity of the samples.Take the edible portions from the samples and blend in a high-speedgrinder. The homogenized portions are thoroughly mixed to make the sample to be detected.The samples needn't to be carbonized and reduced to ashes.By means of the standard point radioactive resource of Co-60 and Eu-152,the energy calibration of the Y -ray spectrometry was made.Record the relation between energy at the full energy peak and the channel position.Using computer to make the fit with a linear least -quare quadratic and to get the correlation between energies and channels.The method of instrumental constant: Take the standard water resource of Cs-137 as standard resource to get the instrumental constant. Spectrometry was obtained to calculate the radioactivity of Cs-137 in the samples with instrumental constant.The method of detection efficiency: By means of the standard radioactive resource of Eu-152,the efficiency calibration of the Y -ray spectrometry was made.The curve of efficiency calibration which shows the relation between energy and detection efficiency was established.By means of some technical methods, some interferential fectors such as self-absorption was eliminated or reduced to the degree that the effect can be neglected.By means of the fit of detection efficiency,many kinds of radionuclides can be detected at one time.But,for the samples with different medium and density, the method should be fitted by self-absorption, and this need further research and study.