Automated Spectrometer for Radionuclide Analysis of Liquid and Gaseous Flows

The automated spectrometer based on HPGe detector of 10% efficiency is intended for technological monitoring of the radionuclide specific activity in liquid and gaseous flows in the on-line mode. The measuring unit (MU) is a U-shaped glass tube embracing the cryostate cover on the level of the detector center which is placed in a lead shield for protection against the background of external radiation. The MU connection to technological systems is made with electromagnetic valves, whose position defines a system´s operation mode. To ensure that there be constant flowing of the monitored medium, a bypass line is provided which connects the inlet pipeline with a system of organized through-flowing. A special algorithm is developed to carry out the measuring procedure consisting in cyclic washing of the MU by water, taking measurements, and subtraction of the current value of background (residual) activity from the measured value of the controlled medium activity. The algorithm ensures a high reliability of the results at measuring the specific activity of liquid or gaseous medium at the presence of surface sorption of radionuclides in the MU. The results of measurements prove that the spectrometer is able to registrate efficiently the radionuclide specific activity in the total activity range in monitored liquid or gas flow up to 7.3 times 10⁶ Bq/l (2 times 10^-5 Ki/l). The detection limit for the specific activity of the radionuclide ¹³¹I is 1.83 times 10³ Bq/l (5 times 10^-8 Ki/l) at the measurement time of 600 s.