A Thermo-Mechanical Analysis for a Nozzle Header of a Once-Through Steam Generator Designed for an Integral Reactor

摘要

Thermo-mechanical behavior of the nozzle header of a steam generator developed for an integral reactor was investigated using experimental and finite element methods. The nozzle feedwater header suffers from severe thermal transient loadings during the operation of the nuclear reactor. The nozzle header is exposed to the low temperature inlet feedwater and the high temperature outlet superheated steam. The other side of the nozzle header is in contacts with the high temperature primary coolant. This temperature gradient results in high thermal stresses in the nozzle header structure. The thermal transient loading has been simulated in the test loop. The thermo-hydraulic parameters of the primary and the secondary system were controlled according to the operation mode programmed in the computer. Strain gauges and thermocouples attached at the highly stressed region monitored the thermo-mechanical behavior of the nozzle header. In parallel to the experimental study, the transient behavior of the nozzle header was simulated utilizing a commercial finite element code. The fluid temperature and the pressure obtained from the test loop were used for the input of the finite element analysis. As a result of this investigation, the thermo-mechanical load carrying capacity of the developed steam generator nozzle header was proved numerically and experimentally.