A passive residual heat removal system plays an important role in cooling the reactor core under accident conditions. The computational fluid dynamics (CFD) software package ANSYS Fluent is used to analyze the influence of malfunction of any 2 of 12 tubes of a passive residual heat removal heat exchanger (PRHR HX) on its performance. Then the computation was validated using the published experimental data. Five different scenarios and a normal condition are computed to analyze the influence of locations of the malfunctioning tubes on the heat transfer performance of the PRHR HX. The results show that the tube defect reduces the amount of heat transferred by the PRHR HX. However, it is correlated with the size of the surface area of the deficient tubes instead of their locations. In other words, analysis suggests that defect tubes with the same surface area should result in similar damage regardless of the location.