Initial Results from Investigations to Enhance the Performance of High Temperature Irradiation-Resistant Thermocouples

概要

論文の詳細を見る
Several options have been identified that could further enhance the lifetime and reliability of thermocouples developed by the Idaho National Laboratory (INL) for in-pile testing, allowing their use in higher temperatures applications (up to at least 1700 °C). A joint project between the INL and the University of Idaho (UI) is underway to investigate these options and, ultimately, provide recommendations for an enhanced thermocouple design. This paper presents preliminary results from this UI/INL effort. Tests show that unalloyed, but doped, molybdenum wires (ODS-Momolybdenum doped with lanthanum oxide and KW-Mo-molybdenum doped with silicon, tungsten and potassium) better retain ductility at higher temperatures than evaluated candidate undoped developmental alloys (Mo-1.6%Nb and Mo-3%Nb). Thermocouples that contain unalloyed molybdenum were also observed to have better high temperature resolution. Candidate niobium alloys (Nb-1%Zr, Nb-4%Mo, Nb-6%Mo, and Nb-8%Mo) became brittle at lower heating temperatures and shorter durations than any of the wires primarily containing molybdenum. Hence, results indicate that a combination of either ODS-Mo or KW-Mo with Nb-1%Zr appear to be the most favorable configuration. Initial results also show that thermocouple stability can also be improved by using larger diameter wires.