An on-Line Radio-Nuclide Liquid Effluent Monitor with a Reduced Contamination Rate

A problem with on-line monitoring of radionuclides in liquid effluent is the build-up of contamination and background on all wetted surfaces. A combination of beta monitoring, a dual phosphor scintillator, and sample geometry was used to reduce the rate of increase of background compared to other types of monitors. Performance in a nuclear station with an effluent (before dilution) of 1.7MBq/m3 (45uCi/m3) Cs 137 equivalent showed a contamination rate of 800 times less than a monitor without the above features.