Flow measurements were performed with pulsed-neutron activation (PNA) in a specially designed test loop. A stationary neutron generator was used as a neutron source, and the detection of the induced 16N activity in the flow was performed by two bismuth germanate detectors. Stable flow could be produced in the loop and measured with high precision (~0.5% error) by a scale and a stopwatch method, concurrent with the PNA measurement. A series of measurements have been made by varying the position of the detectors, the flow velocity, etc. The accuracy of the various time-averaging methods that are used in the evaluation of the PNA measurement could be assessed by a comparison with the flow calibration data. In particular, the dependence of the error of the different PNA evaluation methods as functions of detector spacing and flow velocity was determined. The measurements are part of a program that seeks to develop a flowmeter suitable for practical applications, which will include backing up the method with flow calculation and signal-processing methods such as neural networks for off-line calibration of the equipment.
