Utilization of eddy current flow meter for sodium flow measurement in FBRs

Liquid metal cooled Fast Breeder Reactors form the second stage of Indian nuclear programme. Prototype Fast Breeder Reactor (PFBR) is 500MWe pool type reactor, which is under construction at Kalpakkam, India. Measurement of sodium flow in the reactor system is essential from both operational and safety point of view. Primary sodium pump discharge, secondary sodium circuit, safety grade decay heat removal circuit and auxiliary sodium circuits are the critical locations in an FBR, where sodium flow measurement is of importance. Apart from this, sodium flow measurement in subassemblies in the core facilitates the detection of flow blockage in the subassemblies. ent magnet flow meter is widely used for pipe flow measurement in sodium systems, however, it cannot be considered for applications like subassembly and pump discharge flow measurements. From the safety point of view, flow through the core should be ensured under all operating conditions in a FBR. Development of suitable flow sensors meeting the dimensional constraints and having accessibility for maintenance is a challenge. An eddy current flow meter was designed and developed for sodium flow measurement in PFBR and the developed probe was tested for its performance in a sodium test rig. The developed ECFM was also used for core flow measurements in Fast Breeder Test Reactor (FBTR), India and in Phenix reactor, France, during its end of life test before decommissioning. This paper discusses the activities related to the development, calibration, testing of ECFM probe for PFBR and results of its utilization for flow measurement in FBTR and in Phenix reactor, France.