In Situ Measurement of Low-Level Radioactivities Using the Compton Suppression Technique

The radionuclides in the gaseous effluent, in the water coolant from the research reactor, and in the surroundings were detected with gamma-ray spectrometry with and without using the Compton suppression technique, depending on the activity levels detected. All gamma-ray spectra were taken at various reactor power levels to investigate the relationship between the gamma-ray activities and the power levels. The linear proportionality between the activities and the power levels is valid to a certain extent. Activity in the water coolant was quite high, so in situ measurement was replaced by the sampling technique. The radionuclide ²⁴Na in the coolant was specifically determined as a function of reactor operating time, and it tended to saturate over time. No manmade radionuclides were present in the surroundings except for ¹³⁷Cs as fallout.