Determination of uranium 238 in urine samples for workers in the phosphate industry using alpha spectrometry

An alpha spectrometry method has been developed and validated to assess the internal dose from uranium isotopes for workers in phosphate mines. The method was able to measure levels down to 2 mBq/L. Though the validation results revealed that the mean relative error was about 20%, the method seems to be appropriate and suitable for the application of occupationally exposure monitoring. The method has been used for routine monitoring of workers in the Syrian phosphate mines for 2 years. The results showed that there was some high activity of uranium 238 in urine samples of the first batch which was attributed to samples contamination from the work environment. In the second batch, the results showed that the activity of uranium 238 for most workers were less than the detection limit. Nevertheless, some workers had some exposures but the calculated doses were low or within the occupational dose limit.