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[en] Experience with Type C thermocouples operating for long periods in the 1400 to 1600 C temperature range indicate that significant decalibration occurs, often leading to expensive downtime and material waste. As part of an effort to understand the mechanisms causing drift in these thermocouples, the Idaho National Laboratory conducted a long duration test at 1500 C containing eight Type C thermocouples. As report in this document, results from this long duration test were adversely affected due to oxygen ingress. Nevertheless, results provide key insights about the impact of precipitate formation on thermoelectric response. Post-test examinations indicate that thermocouple signal was not adversely impacted by the precipitates detected after 1,000 hours of heating at 1,500 C and suggest that the signal would not have been adversely impacted by these precipitates for longer durations (if oxygen ingress had not occurred in this test)
[en] TROI experiments on the interaction of molten corium and water are performed to quantify the risk of a potential steam explosion in a nuclear reactor. In the experiments, a cold crucible technique was used to generate the molten corium. The temperature of a molten corium is one of key parameters which have a strong effect on the behavior of the molten corium and water interaction. As the molten corium has a very high temperature of 2830-3200K, its temperature measurement is very difficult. Generally thermocouples are only used up to 2600K. So an optical pyrometry should be applied to measure the temperature of the molten corium. In the TROI experiment, optical two-color pyrometers are used to measure the corium temperatures. One of the pyrometer is to measure the melt temperature during the melt delivery to the water pool. The melt temperature by the pyrometer has uncertainties due to a spectral transmittance of the view port, and a transient response of the two-color pyrometer. In this paper, uncertainty factors of the optical pyrometry in the TROI experiment, such as a spectral transmittance of a view port, and a time response were discussed
[en] The contact thermocouples introduce method errors into the thermal test results. The influence of the parameters, like the density of the incident thermal flux, the inaccuracy of the thermocouple position in the investigated construction element groove, and thermal characteristics of the groove materials, on the method error is given. The obtained results allow the increase of the precision of temperature measurement at the construction unit thermal tests.
[en] Operation of the Neutral Beam Test Stand(NB-TS) at Korea Atomic Energy Research Institute(KAERI) now reaches to 80 kV-20A for about 10 seconds. Experiments with this kind of enormous power and energy necessarily entail many temperature measurements at various locations of the system, and most of the beam line components require to be monitored of their temperatures. We have been implementing temperature measurement utilizing K-Type and T-Type thermocouples(TCs) and a Pt-100 resistance temperature detector for the instrumentation and control and for establishing calorimetry during the operation of the NB-TS facility
[en] The TOPRE systems uses core exit thermocouples (T/C) and self powered neutron detector (SPND) strings together with connecting cable (background) extensively for continuous 3D-power distribution monitoring. T/C and SPND reliability, repeatability and accuracy have been very satisfactory. However it is important to detect any T/C and SPND malfunctions during operation, since a signal change caused by an undetected malfunction can lead to serious errors in the power-distribution developed by TOPRE. Some new procedures have been developed which are capable to qualify T/C and SPND signals based ion time behaviour of signal collection divided to some groups. Time behaviour is periodically archived from TOPRE database to TOPRE periodical archive during nonstationary operation processes (start-up, rod movement, shutdown,...). Graphical representation of each fresh SPND connecting cable current (background) time dependence shows temporary signal malfunction, which disappears after ca 50 effective days. Correlation between time dependence of given SPND signal and mean signal of arbitrary chosen signal collection during nonstationary operation process is also good measure of qualification. From archived signals a database for validation of in-core measurement signals is created. (author)
[en] A module which provides power to Heat Junction Thermocouple(HJTC) is called Hear Power Supply Module(HPSM). The main roles of HJTC are as below. 1. Measuring reactor coolant level (providing loss of coolant information) 2. Measuring temperature in reactor head area (Calculating subcooled margin in reactor head area) HPSM supplies power to such HJTC and it is equipped in a QIAS-P Cabinet
[en] This paper presents a new design of a very low cost two-channel type K thermocouple interface circuit for micro-controllers. This interface circuit targets accurate temperature measurements for nuclear research instrumentation from 0 up to 250 degree Celsius with 1 degree resolution. The usage of the computational capabilities of a micro-controller is proposed to make an adaptive self calibration for the designed interface circuit. Also, these computational capabilities are used to solve the two major problems associated with thermocouples, namely the thermocouple non-linearity problems and the offset errors resulting from the thermocouple reference junctions
[en] Traditional methods for measuring temperature in-pile degrade at temperatures above 1080 degrees C. Hence, a project has been initiated to explore the use of specialized thermocouples that are composed of materials that are able to withstand higher temperature, in-pile test conditions. Results from efforts to develop, fabricate and evaluate the performance of these specialized thermocouples are reported in this paper. Candidate materials were evaluated for their ability to withstand irradiation, to resist material interactions and to remain ductile at high temperatures. In addition, candidate thermocouples were evaluated based on their resolution over the temperature ranges of interest. Results from these evaluations are reported, and additional on-going development activities are summarized
[en] A small coated conductor coil (central field 1 T at 200 A) was constructed and tested in order to evaluate the benefit and the possible disadvantages of non insulated, double pancake construction, in particular regarding quench protection. The insert coil consists of three double pancakes without turn to turn insulation, and it was impregnated with beeswax. The coil was equipped with voltage taps on each pancake, thermocouples and a quench heater. Quench tests were carried out because quench protection is one of the main issues in developing coil technology for coated conductors. Quenches were induced either by a heater or by exceeding the coil critical current; in all cases the quench protection system was able to detect the quench.
[en] A contamination-free Langmuir probe of novel design is described. Surface contaminants, which lead to erroneous evaluation of plasma parameters by distortion of the probe's current-voltage characteristic, are removed by the indirect heating of the probe tip with separate heating elements running parallel to the probe wire in multibore alumina tubing. This configuration minimizes magnetic field perturbations, while maintaining the compact profile and construction ease of an unheated probe. The design and operating characteristics of such a probe are reported. Temperatures at the probe tip, as measured by a subminiature thermocouple, can exceed 500 degree C. Experiments determining the effect of probe temperature, Tprobe, on the characteristic have been performed in a Q-machine plasma (Ti∼Te∼0.2 eV). We find that for Tprobe<250 degree C, the measured electron temperature is up to several times too large, indicating the presence of a contamination layer. This contamination layer is removed for Tprobe ≥300 degree C, and accurate electron temperatures are recovered