Study of the possibility of high accuracy flow measurements with the pulsed neutron activation method
Abstract The performance of water flow measurements with pulsed neutron activation (PNA) have been investigated in the past few years. In this report the following particular Problems were investigated: (a) the effect of collimation on the time-resolved detector signals; (b) the behavior of the background signal, in order to expedite optimum background elimination from the measured signals; and (c) the properties of water mixing, by measuring the geometrical asymmetry of the activated volume as a function of distance from the source as well as of flow velocity. It was seen that with the flow velocities and Reynolds numbers in the present experiments, the mixing is not perfect. Thus, in general, the PNA method will lead to an underestimation of the mass flow due to the effect of the laminar layer close to the wall whose contribution to the total mass flow will be enhanced. The investigations reported here contribute to the improvement of the accuracy of the method.