Determination of 235U content of samples by gamma spectrometry

It is possible to determine 235U content of any sample by non-destructive gamma spectrometry.For this purpose, two reliable methods have been used depending on the experimental conditions: Absolute and comparative methods. Absolute spectrometric method has certain advantages, such as simplicity and shorter measurement times. This method cannot be applied to highly enriched samples because the measurements also depend upon the 238U activity of the sample. At the same time due to the uncertainties in detector efficiency, sample mass, gamma yields and other decay parameteters, etc., it may be difficult to achieve required sensitivities with this method. Because of the above mentioned measurement and decay parameters affecting the sensitivity of absolute method, similar to other laboratories, comparative method has been selected for 235U measurements. The basic principal of this method is the comparisonbetween the results of a sample and a calibration standae-rd material of known enrichment. For this purpose, standards containing various amounts of 235U have been used. In the comparative method, the principle of ''Enrichment Meter'' has been applied or chemically prepared sample and standards are measured by gamma spectrometry depending on the shape and amount of the sample