The Method of Construction of a Dual Johnson-Noise-Power and Resistance Thermometer for1375 K (1100° C) Service in a Vacuum Environment
- Oak Ridge National Laboratory (ORNL) -- Retired
- Oak Ridge National Laboratory (ORNL)
The design and methods of fabrication are described for resistance thermometers that will operate at 1375 K (1100{degrees}C), unattended in a vacuum for a 10-year service life, with high reliability. The expected dc calibration drift of the thermometers is corrected by concurrent measurements of the Johnson noise temperature of the thermometers. These thermometers were to be used on the SP-100 space reactor, which requires a diverse temperature measuring system to complement the high-temperature thermocouple. A major problem was that the thermometer`s long-term durability might be compromised by chemical reactions between the thermometer components. To avoid this problem, thermometers were constructed by using ultrahighpurity, crushable ceramic insulation and metallic components which were cleaned and handled so they would retain their purity during the construction of the thermometer. A unique method of fabrication in an inert atmosphere was developed. Two prototype thermometers were constructed and successfully operated at 1375 K in bench tests. By eliminating moisture adsorption in the ceramic insulation, the thermometer showed high enough resistivity at operating temperatures to avoid electrical shunting errors. Although the SP-100 program has been canceled, the techniques developed in the construction of these thermometers can be applied to other high-temperature thermometers.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 10200226
- Report Number(s):
- ORNL/TM-12696
- Resource Relation:
- Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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