[en] The potential errors in temperature measurements employing small diameter (0.5 mm) metal sheathed thermocouples were analyzed for the Core Flow Test Loop experiments at ORNL. The sources of error considered were extension lead wires, reference junctions, the data acquisition system, calibration and decalibration of the sensors, thermal shunting, electrical shunting, electrical leakage, and electrical noise

[en] The TMI-2 accident indicated that a direct indication of the liquid level in the reactor vessel would have told the operators that the core was being uncovered. This state-of-the-cost survey covered the following methods: heated thermocouple, differential pressure, ultrasonic, capacitance, microwave, time-domain reflectometry, and externally mounted radiation detectors

[en] Two threshold Cherenkov counters that have been fabricated for use with the 20 GeV/c spectrometer are described. The counters were fabricated primarily for use in electron identification in a psi meson experiment but, of course, can be used in the detection of other particles. The counters have now been used in a physics experiment, and have been found to work closely as predicted

[en] This patent describes the method of producing a superconducting product. It comprises providing a pressed-powder preform selected from the group consisting essentially of YBa₂CU₃O_7-x where 0.0 < x < 0.5 and rare earth analogs thereof, preheating the preform to elevated temperature, providing a grain bed and embedding the heated preform in the bed

[en] Tests were conducted to determine the operating limits of fuel cladding thermocouples installed inside the fuel rods for the loss-of-fluid test (LOFT) F2 fuel bundle test. This investigation was conducted to determine (a) the range of time and temperature exposure over which reliable performance can be expected for the dual diameter, 0.040/0.020-in.-diam, Inconel-clad, MgO-insulated, type K thermocouples installed in the LOFT F2 fuel bundle, and (b) the effect of reactor fuel preconditioning at various reactor power levels. Grounded, ungrounded, and unjunctioned thermocouples were tested in temperature profiles estimated for reactor power levels of 8, 10, 12, and 14 kW/ft. The estimated peak temperature was 2160⁰F for the highest power level. The effects of fuel preconditioning for eight hours at peak temperatures of 1950⁰F were measured. The results showed that (a) in expected LOFT F2 temperature profiles, thermocouple read-out errors remained less than 1% up to a peak temperature of 1900 to 1950⁰F; (b) thermocouple read-out errors from virtual junction effects increase rapidly with temperatures above 1950⁰F; (c) wire breakage in peak temperature regions did not occur in any of the tests; and (d) thermocouple performance did not measurably improve nor degrade as a result of eight hours of preconditioning at 1950⁰F. The test data taken with the estimated profiles establish an upper bound on performance errors

[en] Open circuit failures (up to 100%) in small-diameter thermocouples used in electrically heated nuclear fuel rod simulator prototypes during thermal cycling tests were investigated to determine the cause(s) of the failures. The experiments conducted to determine the relative effects of differential thermal expansion, wire size, grain size, and manufacturing technology are described. It was concluded that the large grain size and embrittlement which result from certain common manufacturing annealing and drawing procedures were a major contributing factor in the breakage of the thermocouple wires

[en] This report summarizes the research and development on 0.5-mm-diameter, compacted, metal sheathed thermocouples. The objectives of this research effort have been: to identify and analyze the sources of temperature measurement errors in the use of 0.5-mm-diameter sheathed thermocouples to measure the surface temperature of the cladding of fuel-rod simulators in the Core Flow Test Loop (CFTL) at ORNL; to devise methods for reducing or correcting for these temperature measurement errors; to estimate the overall temperature measurement uncertainties; and to recommend modifications in the manufacture, installation, or materials used to minimize temperature measurement uncertainties in the CFTL experiments

No abstract available

[en] Factors limiting the accuracy of temperature measurements with type K and type S sheathed thermocouple assemblies are discussed. The effect of short-range ordering in Chromel is shown to limit the accuracy of temperature measurements made with type K thermocouple to about 1%. Errors of as much as 150% have been observed in type K thermocouples in magnetic fields at temperatures below the Curie temperature of Alumel. Both positive and negative errors were observed when the orientations of the applied magnetic field, the temperature gradient and the axis of the Alumel wire were such as to produce an emf along the thermocouple wire due to the Nernst--Ettingshausen effect

No abstract available