Articles techniques et présentations

Liquid Metal Fast Breeder Reactor (LMFBR) employs molten sodium as coolant due to its suitable neutronic and thermal properties. Measurement of coolant flow rate is a very important factor both from operational and safety aspects of a fast reactor. Good electrical conductivity of liquid sodium is often exploited to deploy different electromagnetic devices for instrumentation purposes. For measurement of sodium flow rate, Eddy Current Flow Meter (ECFM) is also used in some applications. The output of such ECFM depends on a number of factors. An accurate assessment of the output requires solution of both Maxwells’s and Navier Stokes Equations, which is computationally a very challenging task. The ECFM consists of three coils- one primary and two identical secondary coils. The primary winding is excited by alternating current supply which creates a magnetic field which in turn induces voltages in the two secondaries. Under static condition both the secondaries give equal voltages whereas, when liquid metal is under motion, difference of the two secondary voltages is proportional to the flow rate of liquid metal around the sensor. The output of the flow meter depends on a number of design factors. The output also gets affected by mechanical position and tilt of the sensor. To analyze the impact of these factors, a three-dimensional numerical modeling of the ECFM was carried out using multi-physics based COMSOL software. This paper describes the details of the 3-D numerical model of ECFM. Effect of position and tilt of the sensor on the output is also presented.