Transmutation of thermocouples in thermal and fast nuclear reactors

Scervini, M.; Rae, C.M.F.; Lindley, Ben

doi:10.1109/animma.2013.6727900

Cited by 13 publications

(12 citation statements)

References 2 publications

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“…However, the output signal from a thermocouple is weak, has low resolution, and is highly sensitive to common mode noises, which compromises their accuracy. Additionally, the sensor performance is affected by oxidation and the temperature readings drift significantly under long-duration exposure to high temperature and radiation [ 6 , 7 ]. This often necessitates sensor recalibration due to transmutation from absorption of neutrons [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

Chalcogenide Glass-Capped Fiber-Optic Sensor for Real-Time Temperature Monitoring in Extreme Environments

Badamchi

Simon

Mitkova

et al. 2021

Sensors

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We demonstrate a novel chalcogenide glass (ChG)-capped optical fiber temperature sensor capable of operating within harsh environment. The sensor architecture utilizes the heat-induced phase change (amorphous-to-crystalline) property of ChGs, which rapidly (80–100 ns) changes the optical properties of the material. The sensor response to temperature variation around the phase change of the ChG cap at the tip of the fiber provides abrupt changes in the reflected power intensity. This temperature is indicative of the temperature at the sensing node. We present the sensing performance of six different compositions of ChGs and a method to interpret the temperature profile between 440 ∘C and 600 ∘C in real-time using an array structure. The unique radiation-hardness property of ChGs makes the devices compatible with high-temperature and high-radiation environments, such as monitoring the cladding temperature of Light Water (LWR) or Sodium-cooled Fast (SFR) reactors.

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Section: Introductionmentioning

confidence: 99%

Chalcogenide Glass-Capped Fiber-Optic Sensor for Real-Time Temperature Monitoring in Extreme Environments

Badamchi

Simon

Mitkova

et al. 2021

Sensors

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“…These thermocouples types, which are used routinely for high-temperature measurements outside of the reactors, are only used in very special circumstances for reactor experiments. Type K and Type N thermocouples are affected to only a limited extent [4,5] by neutron irradiation.…”

Section: Introductionmentioning

confidence: 99%

Performance of Custom-Made Very High Temperature Thermocouples in the Advanced Gas Reactor Experiment AGR-5/6/7 during Irradiation in the Advanced Test Reactor

et al. 2020

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The Advanced Gas Reactor-5/6/7 (AGR-5/6/7) experiment is the fourth and final experiment in the AGR experiment series and will serve as the formal fuel qualification test for the TRISO fuels under development by the U.S. Department of Energy. Certain locations in this experiment reach temperatures higher than any of the previous AGR tests, up to 1500°C. Such extreme temperatures create unique challenges for thermocouple-based temperature measurements. High-temperature platinum-rhodium thermocouples (Types S, R, and B)and tungsten-rhenium thermocouples (Type C) suffer rapiddecalibration due to transmutation of the thermoelements fromneutron absorption. For lower temperature applications, previousexperience with Type K thermocouples in nuclear reactors haveshown that they are affected by neutron irradiation only to alimited extent. Similarly, Type N thermocouples, which are morestable than Type K at high temperatures, are only slightly affectedby neutron fluence. Until recently, the use of these nickel-basedthermocouples was limited when the temperature exceeds 1050°Cdue to drift related to phenomena other than nuclear irradiation.Recognizing the limitations of existing thermometery to measuresuch high temperatures, the sponsor of the AGR-5/6/7 experimentsupported a development and testing program for thermocouplescapable of low drift operation at temperatures above 1100°C. High Temperature Irradiation Resistant Thermocouples (HTIR-TCs)based on molybdenum/niobium thermoelements have been underdevelopment at Idaho National Laboratory (INL) since circa 2004. A step change in accuracy and long-term stability of thisthermocouple type has been achieved as part of the AGR-5/6/7thermometry development program. Additionally, long-termtesting (9000+ hrs) at 1250°C of the Type N thermocouplesutilizing a customized sheath developed at the University ofCambridge has been completed with low drift results. Both theimproved HTIR and the Cambridge Type N thermocouple typeshave been incorporated into the AGR-5/6/7 test, which beganirradiation in February 2018 in INL’s Advanced

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“…On the contrary Ni based thermocouples are less affected by transmutation [3,4] and quite stable in nuclear environments [3,4,7]: type K thermocouples irradiated between 200 and 1000°C in several different reactors experienced drift always within about ±5°C [7]. As a result, Nickel based thermocouples are considered a suitable candidate for nuclear applications and they are often used in Mineral Insulated Metal Sheathed (MIMS) configuration (Fig.1).…”

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confidence: 98%

“…Pt based thermocouples and W based thermocouples are T significantly affected by transmutation [3,4], leading to very significant drift. Pt based thermocouples experienced a drift as high as -30°C at about 1030°C, when irradiated with a fluence of 4.2·10 20 neutrons/cm 2 [5].…”

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confidence: 99%

Low drift type N thermocouples in out-of-pile advanced gas reactor mock-up test: Metallurgical analysis

Scervini

Palmer

Haggard

et al. 2015

2015 4th International Conference on Advancements in Nuclear Instrumentation Measurement Methods and Their Applications (ANIMMA

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Thermocouples are the most commonly used sensors for temperature measurement in nuclear reactors. They are crucial for the control of current nuclear reactors and for the development of GEN IV reactors. In nuclear applications thermocouples are strongly affected by intense neutron fluxes. As a result of the interaction with neutrons, the thermoelements of the thermocouples undergo transmutation, which produces a time dependent change in composition and, as a consequence, a time dependent drift of the thermocouple signal. Thermocouple drift can be very significant for in-pile temperature measurements and may render the temperature sensors unreliable after exposure to nuclear radiation for relatively short times compared to the life required for temperature sensors in nuclear applications. Previous experiences with type K thermocouples in nuclear reactors have shown that they are affected by neutron irradiation only to a limited extent. Similarly type N thermocouples are expected to be only slightly affected by neutron fluxes. Currently the use of Nickel based thermocouples is limited to temperatures lower than 1000°C due to drift related to phenomena other than nuclear irradiation. As part of a collaboration between Idaho National Laboratory (INL) and the University of Cambridge a variety of Type N thermocouples have been exposed at INL in an Advanced Gas Reactor mock-up test at 1150°C for 2000 h, 1200°C for 2000 h, 1250°C for 200 h and 1300°C for 200 h, and later analysed metallurgically at the University of Cambridge.The use of electron microscopy allows to identify the metallurgical changes occurring in the thermocouples during high temperature exposure and correlate the time dependent thermocouple drift with the microscopic changes experienced by the thermoelements of different thermocouple designs.In this paper conventional Inconel 600 sheathed type N thermocouples and a type N using a customized sheath developed at the University of Cambridge have been investigated. The rationale for the superior performance of the type N using a customized sheath developed at the University of Cambridge is explained in comparison with the behavior of conventional type N Inconel600 sheathed thermocouples. I. THERMOCOUPLES FOR NUCLEAR APPLICATIONSHERMOCOUPLES at high temperatures experience drift, a time dependent departure of the thermocouple signal from the real temperature of the environment. Thermocouple drift introduces a time dependent error in the temperature reading of the sensor.Metallurgical modifications occurring along the length of the thermocouple are responsible for drift. In nuclear applications thermocouples experience not only high temperatures, responsible for temperature activated microstructural or compositional changes, but also neutron irradiation, which produces:Atomic displacements generate dislocation loops and voids into the irradiated materials.With sustained irradiation the dislocation loops density increases. Macroscopically the effects are equivalent to cold work: increased hardening, reduced te...

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Transmutation of thermocouples in thermal and fast nuclear reactors

Cited by 13 publications

References 2 publications

Chalcogenide Glass-Capped Fiber-Optic Sensor for Real-Time Temperature Monitoring in Extreme Environments

Chalcogenide Glass-Capped Fiber-Optic Sensor for Real-Time Temperature Monitoring in Extreme Environments

Performance of Custom-Made Very High Temperature Thermocouples in the Advanced Gas Reactor Experiment AGR-5/6/7 during Irradiation in the Advanced Test Reactor

Low drift type N thermocouples in out-of-pile advanced gas reactor mock-up test: Metallurgical analysis

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