A New Thermometry for Liquid Sodium

A new thermometry for liquid sodium, which stands on the low resistivity and the moderate thermo-emf of liquid sodium, has been developed upon the demand on the individual subassembly outlet instrumentation in the sodium-cooled fast-breeder reactor, which requires "the more reliable and precise informations with the higher sensitivity at the less sacrifice and cost". Unusual thermo-electric combinations of " chromel-sodium-alumel" and "chromel-sodium-chromel" are studied to obtain more informations through the same number of sensors and lead-wires. Also a unique combination of "stainless steel-sodium-stainless steel" is tried as the fast-response temperature fluctuation detector, which would make the detection of a few overheated pins in one subassembly possible. These feasibilities are preliminarily analized. The transient responses are graphically solved by a newly developed method. Some interesting presuppositions are obtained. Experiments are proceeded on the existing sodium loops, on the simple sodium pot, and on some melting solder baths. No definite objection raises. The new thermometry is considered to be feasible and useful, not only as the individual subassembly instrumentation, but also as the surface temperature detector, as the temperature fluctuation detectors for the transit-time and Karman vortex flowmeters, and as some experimental means for liquid sodium.