EPJ Web Conf.
Volume 253, 2021ANIMMA 2021 – Advancements in Nuclear Instrumentation Measurement Methods and their Applications
|Number of page(s)||4|
|Section||Severe Accident Monitoring|
|Published online||19 November 2021|
Optimized High-Temperature Irradiation-Resistant Thermocouple for Fast-Response Measurements
Idaho National Laboratory, USA
2 Analysis and Measurement Services, USA
Published online: 19 November 2021
The high-temperature irradiation-resistant thermocouple is the only temperature probe proven to withstand the high-temperature (>1290°C), high-radiation (a fluence of up to ∼1 × 1021 n/cm2) environments of nuclear reactor fuel design testing and/or over-temperature accident conditions. This report describes the improved performance of a molybdenum and niobium thermocouple by utilizing a coaxial design (i.e., a single wire grounded to the outer sheath). This optimized high-temperature irradiation-resistant thermocouple features a simplified design yet allows for more robust individual components. The niobium and molybdenum thermoelements can be used interchangeably in either the sheath or wire, depending on the intended application. Via a plunge test in flowing water, the response time of the coaxial build of the high-temperature irradiation-resistant thermocouple was determined to be 30x faster than that of the comparable ungrounded type-K thermocouples, and 10x faster than the grounded type-K thermocouples and traditional ungrounded high-temperature irradiation-resistant thermocouples (i.e., two-wire configurations). Furthermore, by capitalizing on the coaxial design, a multi-core high-temperature irradiation-resistant probe with multiple “single-pole” wires along the length of the sheath was proven feasible. This multi-core, thermocouple design was dubbed a “demicouple.” The high-temperature irradiation-resistant demicouple is primarily applied during fuel experiments to record multiple fuel-pin centerline temperature measurements using a single compact sensor. Furthermore, the shared “common” leg between demicouple junctions reduces error propagation in secondary measurements such as temperature differentials.
Key words: Thermocouple / Irradiation-Resistant / In-pile / Sensor
© The Authors, published by EDP Sciences, 2021
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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