Velocity and Flow Rate Measurement in a Natural Circulation Helium Loop

In nuclear energy power plants, operational safety is of utmost importance. A high- pressure natural circulation loop filled with helium enables the cooling of the residual heat from the reactor. Several operational parameters shall be measured, including measurement of the helium flow velocity and mass flow rate by Pitot tubes. The paper discusses the operational conditions of such measurement, and a suitable design and summarizes uncertainty sources. It also provides a comparison of measured and simulated discharge velocities, which are in a good match, and suitable for intended purposes. Moreover, the measurement results proved the significant impact of the flow type on measured velocities (thus also mass flow), where even the partial inhomogeneities in the helium flow generate the undesired influence on the Pitot tube accuracy. These results are of a preliminary nature and need to be further précised.