Abstract
The endplate in feedwater heater at TPC NPP#3 had found broken and thinned when NPP#3 repair it at 2000. NPP#3 provide several method to solve this problem. Including water level increase and endplate thickness increase. In this thesis, we will discuss the effect of water level increase by the heat exchanger model of feedwater heater.Feedwater heater is the machine which use steam to heated the feedwater, to increase the efficiency for all nuclear power plant. In this thesis, we establish heat exchanger model to calculate the efficiency for feedwater heater which varied by the change of water level in the condensing zone. We expect to find the heat exchanger model which can conform with the test data from the NPP#3. In this model, it shows the trends in shell-and-tube end temperature difference vs. water levels are in good agreements with plant test data. But the data is larger than the test data from the plant, we do a sensitive test for it. The approach is more good for the exchanger model.We can find that the end temperature difference will suddenly rise when the operation water level too lower. We called the phenomenon “break point”. If the operation level increase can decrease the endplate broken and thinned in the feedwater heater. We suggest that increase the operation level, because the affect of efficiency is not varied very large. It is extend the usage time of the feedwater heater, and to avoid some unexpected problem with the thinned and broken endplate.