Abstract: The heat exchanger tube bundle fluid entry area is a region where particular problems can occur because pieces of metallic debris can collect and focus their mass at this low elevation. The metallic debris collected at the bottom of the annular downcomer passage can be swept into the tube bundle, wherein they will impact upon the tube bundle and can cause repture or large amounts of wear to the heat transfer tubes. To prevent this adverse condition, a circumferential row of cylindrical members are positioned peripherally about the entry portion of the tube bundle. These members will have an outside diameter, pitch, and geometric array corresponding to that of the heat tranfer tubes, so as to minimize pressure drop, due to flow across them.