Development of Level Sensor for Lead – Lithium Loop System

Lead-Lithium (Pb-Li) eutectic alloy is considered as the coolant in Indian Lead-Lithium ceramic breeder blanket. This liquid metal alloy is circulated through the blanket modules of fusion reactors at operating temperatures around 450°C. The Lead- Lithium system which supplies the alloy to the blanket module is operating at high temperature and needs redundant level measuring sensors along with other diagnostic devices. The high operating temperature, high chemically active nature of Pb-Li alloy and its reaction with air make its instrumentation difficult over conventional instrumentation. Since Lead Lithium is a good conductor of electricity, mutual inductance type continuous level sensors is the best choice. Design and development of the level sensor has been taken up based on the experience of mutual inductance level sensor used in sodium systems. This paper provides a brief discussion about conceptual design, specifications, modeling and simulation using Finite Element Method Magnetics (FEMM), study on skin depth and temperature compensation of sensor output for the mutual induction type continuous level sensor designed for Pb-Li loop system. It also includes the experimental validation of the level probe using solid aluminum blocks in place of Lead-Lithium alloy.