In situ calibration and evaluation of the accuracy of a waste water monitoring system.
A new method to estimate the reliability of a waste water monitoring system was developed and substantiated. To estimate the reliability means (1) to verify the representativeness of the sample fed into the monitoring system, and (2) to calibrate the detectors of the monitoring system. To verify the representativeness, test water spiked with 32P was prepared in a storage tank, and the monitoring system was operated. For all of the experiments, the radioactivity concentrations of the water fed into the monitoring system agreed well with those of the water in the storage tank at 725 +/- 45 s after the start of the sampling pump. Therefore, the representativeness was verified. Calibration was carried out with active water in the storage tank and in a specially designed calibration tank. The efficiency of a plastic scintillation detector (PSD), one of the detectors used in the monitoring system, for 32P was determined to be 4.91 +/- 0.10%. Using the calibration tank significantly reduced the cost and labor for calibration. In addition, calibration with natural potassium (40K) proved to be effective for periodic checks of the detector.
Ogata
Yoshimune
Y
Department of Radiological Technology, Nagoya University School of Health Sciences, Japan. ogata@met.nagoya-u.ac.jp
Nishizawa
Kunihide
K
D002138:Calibration; D004307:Dose-Response Relationship, Radiation; D010761:Phosphorus Radioisotopes / Q000032:analysis; D011197:Potassium Radioisotopes / Q000032:analysis; D015203:Reproducibility of Results; D013997:Time Factors; D018505:Waste Management / Q000379:methods*; D014867:Water / Q000032:analysis*; D014878:Water Pollution, Radioactive / Q000032:analysis
D010761:Phosphorus Radioisotopes; D011197:Potassium Radioisotopes; D014867:Water