Assessment of fuel thermocouple decalibration during in-pile service

Behavior of tungsten under irradiation and plasma interaction

“…The compositional variation induced a decrease in the thermoelectromotive force; this means that the temperature was lower than the actual temperature. Vintanza et al corrected the actual data of the reactor irradiated TC and proposed a recalibration correlation as a function of thermal neutron fluence[526]. In the 1990s, the effects of neutron irradiation on mechanical properties of W and other refractory metals continued to be studied.…”

Improving High-Temperature Measurements in Nuclear Reactors with Mo/Nb Thermocouples

“…Such a response demonstrates that different Fig. 2 Evolution of the signal measured by different thermocouples during the endurance test at 1100 • C, and indication of the expected in-pile drift of a Type C thermocouple under a constant thermal neutron flux of 4 × 10 18 n · m −2 · s −1 (this last calculation is based on literature values from in-pile measurements reported in [3] and [9]). A picture of the specific high-temperature bench test is presented under the graph and successive phenomena occurred in this thermocouple during its operation.…”

“…As an indication, Fig. 2 includes a representation of the expected in-pile drift of a Type C thermocouple when exposed to a thermal neutron flux of 4 × 10 18 n · m −2 · s −1 , which is typical of a MTR core environment (this calculation is based on literature values from in-pile measurements reported in [3] and [9]). …”

Assessment of High-Temperature Measurements for Use in the Gas Test Loop

“…A second report [27] by Halden scientists analyzed the results of several empirical tests and cited some of the same studies examined by Walter [2]. The Halden authors divided the various empirical results into two groups, one averaging -5.0 percent decalibration and the other -11.0 percent decalibration for a thermal neutron fluence of 1E+21 n/cm 2 .…”