High Temperature Thermometry at Canel

Thermocouples made at CANEL have been operated for long periods at temperatures between 2000F and 2500F. Data are presented on extended use in nuclear reactors and in non-nuclear environments. Thermocouples have been operated in inert gas and in liquid alkali metal. The thermocouples discussed are compacted-ceramic insulated, metal sheathed, and hermetically sealed. Detailed discussion is presented on Cb-1Zr sheathed, alumina insulated, chromel/alumel thermocouples. These have been tested and widely used at temperatures of 2000F to 2200F for 10,000 hours in liquid metal, in a reactor flux of 1013 nvt. Fabrication procedures and material specifications are presented in detail. Other thermocouple systems discussed are W-5Re/W-26Re and Mo/Cb. Transmutation effects are evaluated and explained with reference to resonance cross-sections. Failure mechanisms are discussed.