[en] On line monitoring system for the determination of uranium in the process streams using 185.7 keV gamma ray of ²³⁵U have been developed. Suitable simulated container was designed for maximum detection efficiency. The efficiency calibration of the gamma ray detection system was developed using standard solutions of uranium in concentration range from 10 to 260 mg/litre. The calibration plot was found to be a straight line. This calibration plot can be used to determine the unknown amount of uranium in any solution of the process stream. In order to correct for the density variation of the solution in the process stream, experiment was carried to study the variation of count rate of 185.7 keV gamma ray of ²³⁵U with density of the solution. The variation up to 8.6% in the count rate was found for variation of density from 1 to 1.71. (author)