Five iron–carbon (Fe–C) eutectic fixed-point cells have been constructed between NPL and LNE-Cnam to investigate the robustness and to measure the agreement of their melting temperatures. Each cell was constructed with a different selection of materials sourced by NPL and LNE-Cnam. The measured emfs at the Fe–C fixed-point temperature (∼1153 °C), compared between cells, agree within around 1.98 µV (∼90 mK), where the most important contribution to the uncertainty of each measurement is the inhomogeneity associated with the measuring Pt/Pd thermocouple. This demonstrates that these cells are suitable for use as secondary fixed-point cells in contact thermometry but the robustness of the presented cells is not found to be sufficient for maintaining their integrity during repeated cycling procedures.
Articles you may be interested inHigh-temperature fiber-optic Fabry-Perot interferometric sensors Rev. Sci. Instrum. 86, 055001 (2015); 10.1063/1.4919409 Fiber optic sensors for nuclear power plant applications AIP Conf. Thermally compensated temperature sensor capable of highly accurate measurements on surfaces Rev. Sci. Instrum. 78, 094901 (2007);Abstract. The European metrology research programme (EMRP) allows funding for metrology-oriented projects in the frame of targeted calls aimed at improving metrology for important contemporary and future needs in different fields such as energy, environment and industry. A joint research project (JRP), called "MetroFission", was selected for funding in the "Energy" call of 2010. This JRP, led by NPL (UK), aims to anticipate and to start addressing the metrological needs of the next generation of nuclear power plants. The need for improving the accuracy and reliability of temperature measurements at temperatures higher than those currently measured in nuclear power plants is dealt with in the first workpackage of the project. This project started in September 2010 and will last for three years. This paper summarizes the activities of the first half of the project and the expected final achievements, which will be essentially oriented towards new temperature references and new devices, adapted to the high temperature range as well as the particularly harsh working conditions.
Raman distributed temperature sensing (DTS) technologies are currently under evaluation by the nuclear and hydraulic industries as it may bring promising alternatives to classical measurement techniques. The reliability of the DTS measurements, as well as the traceability to the temperature standards, must be ensured throughout the entire period of monitoring (typically over a few tens of years). In order to achieve this goal, one key task consists in the verification of the performances claimed by the DTS devices manufacturers. Thus, the metrological performances and characteristics of the DTS devices, such as their limitations and accuracies, as well as the practical aspects of systems implemented on site should be evaluated step by step. This paper describes the dedicated facilities which have been developed at LNE in order to evaluate and to qualify DTS devices for very demanding applications. A first case study performed on one specific DTS device is detailed. A systematic bias has been observed among others on the spatial resolution. The DTS response to a temperature variation step over 1 m (spatial resolution typically claimed by the manufacturers) of sensing optical fibre corresponds indeed to only 90% of the temperature step magnitude, whereas the full DTS response is obtained in fact for 10 m (the practical spatial resolution) of sensing optical fibre solicited by this temperature step variation.
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