Process flow measurement based on tracer techniques

Flow measurement methods based on the tracer techniques are the transit time method as well as methods based on tracer dilution. These methods can be applied to the on-site calibration of flowmeters and to measuring the flowrate where no flowmeter is installed. The accuracy of the tracer methods depends on the prevailing measuring conditions. In this report the accuracy of the transit time method under field conditions is estimated to be 1-2% on the 99,7% confidence level. The accuracy of the isotope dilution method is estimated as slightly better, namely about 0.5% at its best. An even better accuracy, about 0.2%, could be achieved by developing the method and the measuring equipment. Tests were carried out with the transit time method for water and steam flow. While measuring water flow the effect of different measuring parameters upon the repeatability of the method were looked into. Such were the number of the detectors and the distance between the measuring points. Different means of tracer injection were tested, as well. These had less effect than expected. The accuracies achieved in steam flow measurements were of the same order of magnitude as in water flow measurements. The tracers used were 137mBa for water flow and 41Ar for steam flow measurements