Implementation of gamma-ray spectrometry in two real-time water monitors using NaI(Tl) scintillation detectors

• Gamma-ray spectrometry with NaI(Tl) detectors was implemented in two water monitors.
• The monitors were calibrated using experimental data and Monte Carlo simulations.
• The efficiency calculations and MDAC values are given.
• Advantages of using gamma-ray spectrometry are discussed.
• The monitors permit the identification and quantification of isotopes in water.

In this study, the implementation of gamma-ray spectrometry in two real-time water monitors using 2 in.×2 in. NaI(Tl) scintillation detectors is described. These monitors collect the water from the river through a pump and it is analyzed in a vessel, which is shielded with Pb. The full calibration of the monitors was performed experimentally, except for the efficiency curve, which was set using validated Monte Carlo simulations with the EGS5 code system.After the calibration, the monitors permitted the identification and quantification of the involved isotopes in a possible radioactive increment and made it possible to discard possible leaks in the nuclear plants. As an example, a radiological increment during rain is used to show the advantages of gamma-ray spectrometry. To study the capabilities of the monitor, the minimum detectable activity concentrations for 131I, 137Cs and 40K are presented for different integration times.