METHODS OF MEASURING TEMPERATURE IN NUCLEAR REACTORS
The safe operation of high-power nuclear reactors depends upon the accurate measurement of temperatures of their components. Temperature measurement devices are affected by nuclear radiation, heat flux, and other conditions which exist in nuclear reactors. Thermocouples are used in reactors more than other methods because of their small size, remote output and relative insensitivity to radiation. Theoretical considerations suggest that the effects of radiation other than transmutation on thermocouples should not be large and this is borne out by experiment. Changes in composition of thermocouples by transmutation alter their calibration. Chromel-Alumel is affected to only a small degree; alloys containing iridium, rhodium, tungsten, or rhenium may be affected grossly. Applications of thermocouples to special problems in reactors are discussed. Other methods of temperature measurement are reviewed. Resistance thermometers are large and affected by radiation and by heat flux. Radiation pyrometers are affected by internal gamma heat or by radiation damage to optical components. Thermistors are seriously damaged. The substitution for temperature by the concept integral kd theta is discussed for fuel element interiors. Temperature measurement by differential expansion, sound velocity, diffusion, and by pneumatic probes is reviewed. Insulation materials are damaged by nuclear radiation. Ceramic or binder-free silica glass fiber insulation performs well in reactors. It is concluded that most requirements for measuring reactor temperatures can be met by selected thermocouples and insulators. Other methods are of interest for special applications. (auth)
- Research Organization:
- Oak Ridge National Lab., Tenn.
- NSA Number:
- NSA-17-040308
- OSTI ID:
- 4648046
- Journal Information:
- Progr. Nucl. Energy, Ser. IV, Journal Name: Progr. Nucl. Energy, Ser. IV Vol. Vol: 5
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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DIFFUSION
FIBERS
FUEL ELEMENTS
GAMMA RADIATION
GLASS
HEATING
IRIDIUM ALLOYS
MEASURED VALUES
OPERATION
PNEUMATICS
PYROMETERS
RADIATION EFFECTS
RADIATIONS
REACTOR TECHNOLOGY
REACTORS
RESISTORS
RHENIUM ALLOYS
RHODIUM ALLOYS
SEMICONDUCTORS
SENSITIVITY
SOUND
STANDARDS
TEMPERATURE
THERMAL INSULATION
THERMAL STRESSES
THERMISTORS
THERMOCOUPLES
THERMOMETERS
TUNGSTEN ALLOYS
VARIATIONS
VELOCITY