1987 Volume 36 Issue 2 Pages 64-69
A new non-destructive analytical method for 226Ra has been proposed which corrects the activity of 226Ra determined by γ-ray spectrometry, using that of 238U determined by the epithermal neutron activation analysis.
The activity of 226Ra obtained by this method was compared with the activity of 214Bi measured more than 30 days after sealing the sample, by the usual non-destructive method, which took such a long time to analyze. The value of 226Ra derived from the 214Bi data fluctuated and was underestimated because of loss of 222Rn probably due to imperfect sealing. The present method is simpler and more rapid, because the consideration of the radioactive equilibrium and the chemical operation are unnecessary.
The new method was applied to the analysis of deep well boring cores obtained at Higashikurume City in Tokyo, and the radioactive equilibrium of uranium series in the cores was discussed. As the results, it has been known that in the sandy and the silty cores, 226Ra/238U ratios are 2.4 and 1.7, respectively, and 214Bi/226Ra ratios are 0.29 and 0.46, respectively.
