Detection Unit of a Gamma-Ray Spectrometer for Measuring the Volumetric Activity of Noble Radioactive Gases

The design and characteristics of the detection unit of a gaseous medium spectrometer for measuring gamma rays from inert radioactive gases formed in nuclear power plant reactors and entering the environment as a part of gas-aerosol emissions are described. Gamma rays from inert radioactive gases are detected by one scintillation detector based on a 51 × 51-mm CeBr3 crystal in two chambers with a volume of 104 and 2 cm3. The energy range of the spectrometer is 0.05–3.0 MeV. Switching of gas inputs and outputs allows both simultaneous and alternate measurements in both chambers, which ensures the calculated dynamic range of measured inert radioactive gas activities from 103 to 1013 Bq/m3 with a relative measurement error of 50% in the nuclide emission lines for time intervals from 1 to 500 s, depending on the activity.