Nuclear Radiation Dose Rate Influence on Thermocouple Calibration

The instantaneous effects of nuclear radiation on thermocouple calibration were measured using Chromel-Alumel and iron-Constantan thermocouples. Electromotive force shifts of 2 to 4°C were found at radiation levels of 10¹⁶ n/(cm² sec) (fast and thermal) and 10¹⁰ R/h. These changes were attributed to local gamma heating of the thermocouple bead rather than to a change in the thermoelectric power of the thermocouple materials. In separate experiments, no transient changes were noted in thermocouple calibration (± 1.0°C) following a change in radiation level of ≤ 7 × 10¹² n/(cm² sec) (thermal and fast) and 7 × 10⁶ R/h.