Continuous Monitoring of Low Level Radioactive Waste Water

A possibility was investigated for monitoring low level radioactive waste water by the Cerenkov effect. The merit compared with other methods. The intensity of Cerenkov light is so weak that it is difficult to discriminate the signals from dark noise pulses of the photomultiplier. The thermal background of the photomultiplier was reduced by cooling the photocathode of the tube and employing coincidence methods. A detecting sensitivity of 3 x 10(sup -7) mu c/ cc was obtained for Sr(sup 90). The maximum sensitivity of the apparatus was limited by thermal noise of the photomultiplier and cosmic ray background. (auth)