Abstract
Thermocouple located near the coolant outlet of the fuel assembly head may indicate a temperature biased by radiation heating and subsequently affect accuracy of incore measurements. The analysis splits into two parts; coupled neutronphoton Monte Carlo transport to determine radiation heating that serves as the input to heat transfer calculation resulting in temperature bias evaluation. Various nuclear reactions contribute to radiation heating in the active volume of the thermocouple steel. Monte Carlo transport calculation of radiation heating for average fuel assembly in one of latest Dukovany NPP cycles was performed with MCNP code. Heating power was compared to values published previously for Paks and Kola NPPs. Heat transfer calculations were performed with TEPLO code developed in SǨODA JS. Radiation heating can be considered as negligible if the axial shift between thermocouple active part and thermocouple socket is below 15 mm.
© 2020 by Walter de Gruyter Berlin/Boston
