Influence of radiation field from a nuclear reactor on melting and solidification of HgI2

The effect of radiation from a nuclear reactor on the performance of a mercury iodide temperature sensor in which the melting transition provides a single temperature reference point (approx.2560C) is investigated. Earlier studies have indicated the importance of the use of boron-free glass in the construction of the bulb containing the HgI2 charge. The results presented confirm this finding. for boron-free glass sensors tested in a reactor, the apparent transition temperature is roughly a linear function of reactor operating power. The maximum change in the temperature point is less than +- 1.50C for typical irradiation conditions. The hysteresis in the melting-solidification cycle was found to decrease with increasing reactor power, mainly as a result of an increase in the solidification temperature. (author)