Thermocouple Signal Sensitivity to the Sheath Thickness of Thermal-Hydraulic Test Facility Indirectly Heated Electric Fuel Pin Simulators

摘要

Analysis of data in large loss-of-coolant accident experminental facilities often requires extensive use of signals recorded from thermocouples embedded in indirectly heated electric fuel pin simulators(EFPS). These signals, converted to temperature, are used in the numerical determination of EFPS experimental conditions, including transient surface temperature distribution. Important points that arise in using the recorded thermocouple signals as a basis for subsequent analysis include (1) the effect of the distance that the thermocouple bead is located from the EFPS surface on the ability of the thermocouple to resolve rapidly changing boundary phenomena and (2) the extent that this depth influences the time response associated with the thermocouple. Several numerically solved EFPS transients (where boundary conditions were specified, and surface temperature, surface heat flux, and internal redial temperature histories were subsequently calculated) are presented in an effort to establish these two relationships and to form a foundation for recommending designs which will minimize the adverse effects of these relationships by specifying optimal thermocouple radial positions in uture EFPSs.