Activation Analysis of Trace Impurities in Metallic Materials for Breeder and Fusion Reactors, and Measurements of Their Specific Activities

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In recent years, fundamental and applicable studies on the developments of most suitable materials for breeder and fusion reactors have been made extensively. In these developments, as a matter of course, the actual conditions of radioactivation due to the major and minor elements and trace impurities in such materials must be seized accurately under a new viewpoint. Although such studies can generally be performed by radioactivation method using the materials analyzed previously with instrumental methods, the above actual conditions of radioactivation containing trace impurities can be achieved only by the use of the internal standard method coupled with the standard addition method as an absolute standardization method, which is resulted simultaneously in the concentrations and specific activities of all of the interesting elements. In the present studies, simultaneous determination of specific activities and concentrations of major alloying elements and impurities, such as Ti, Cr, C … More o, Ni, Cu, As, Zr, Nb, Mo, Sb, Sn and Pb, in many kinds of low and high alloy-steels were performed by photon activation analysis with 20 and 30 MeV bremsstrahlung using the above absolute standardization method, because the above samples are forced to use as irreplaceable materials for breeder and fusion reactors, and because photon activation produces the same radioactivities as those by (n, 2n) reactions due to fast neutrons. Furthermore, measurements of the specific activities produced in the above samples were also carried out similarly by using 60 and 100 MeV bremsstrahlung. On the basis of the results obtained, the actual conditions of radioactivities produced in each sample irradiated for 1000 hours with 20, 30, 60 and 100 MeV bremsstrahlung were calculated, and it was elucidated that the intensities of radioactivities produced in each sample were greatly affected by its major and minor components. On the other hand, simultaneous determination of a variety of impurities in B, Dy, Ho, Ce, Tb, Dy, Ho and/or their compounds as materials for reactors has also been examined by proton activation using the above absolute standardization method. From the results obtained, it was also proved that determination of the impurities in the above samples not only but the actual conditions of radioactivities produced can be seized satisfactory by the above method. Less