Computational-experimental method of evaluating the measurement error in the fuel-element cladding temperature during the simulation of emergencies

The objective of this work is to develop a computational-experimental method of determining the systematic error in measurements of the temperature of cooled fuel-element cladding using a thermocouple secured along the generatrix of the cladding. A method of nondestructive diagnostics of the quality of the thermal contact of the working end of a thermocouple with fuel-element cladding and the conditions for its heat exchange with the coolant and their effect on the measurement error in the temperature of the cooled cladding is examined. The method is based on thermal probing of a thermocouple by passing a current through the thermal electrodes and recording and processing the responses in the presence and absence of the coolant. A relation is derived for the systematic error with stationary and linearly growing cladding temperature. The experimental and computational results for the systematic errors are presented.