부산대학교 도서관

A gamma-ray peak of 226Ra (186.2 keV) overlaps with one of 235U (185.7 keV) in a gamma-ray spectrometry system. Though reference peaks of 235U can be used to correct the peak interference of 235U in the analysis of 226Ra, this requires a complicated calculation process and a high limit of quantitation. On the other hand, evaluating 226Ra using the correction constant in the overlapped peak can make a rapid measurement of 226Ra without the complicated calculation process as well as overcome the disadvantage in the indirect measurement of 214Bi, which means the confinement of 222Rn gas in a sample container and a time period to recover the secular equilibrium. About 93 samples with 6 species for raw-materials and by-products were prepared to evaluate the activity of 226Ra using the correction constant. The results were compared with the activity of 214Bi, which means the indirect measurement of 226Ra, to validate the method of the direct measurement of 226Ra using the correction constant. The difference between the direct and indirect measurement of 226Ra was generally below about ± 20%. However, in the case of the phospho gypsum, a large error of about 50% was found in the comparison results, which indicates the disequilibrium between 238U and 226Ra in the materials. Application results of the contribution ratio of 226Ra were below about ± 10% . The direct measurement of 226Ra using the correction constant can be an effective method for its rapid measurement of raw materials and by-products because the activity of 226Ra can be produced with a simple calculation without the consideration of the integrity of a sample container and the time period to recover the secular equilibrium.