Patent Number: 043137920
Section: abstract

A gamma thermometer for use with a nuclear reactor is provided with two thermocouple junctions which are connected so as to output the difference voltage. The two thermocouple junctions are spaced closely enough so that, considering the scale of the nuclear reactor, they experience the same gamma-ray flux. However, the thermal paths to a common heat sink for the two thermocouple junctions are different, so that the junctions exhibit a temperature difference which depends on, and therefore measures, the heating produced by the gamma-ray flux and, thereby, the gamma-ray flux itself. The gamma thermometer is built on a miniature scale, so that it can be traversed through a small, often dry, bore extending through the core of a nuclear reactor. The temperature difference mentioned above will be affected to some extent by the temperature of the common heat sink. Therefore, to increase accurate repeatability of computed measurement, a thermocouple junction is used to measure the temperature of the common heat sink and, further, a thermal heat bridge may be used to thermally link the common heat sink to the bore.