Double wall tube (DWT) steam generators, which will eliminate the intermediate heat transport system (IHTS) of FBRs, have been studied to enhance the reliability of FBR plants. They are expected to prevent sodium-water reaction, since a steam generator would be brought to shutdown when a water side leak or a sodium side leak is detected. A wire mesh filled DWT, which is one type of a porous metal filled DWT, has been developed to improve leak detection characteristics without significantly decreasing thermal performance. Wire mesh filled DWTs for straight once through type steam generator were trially manufactured to evaluate their characteristics. A Mod. 9Cr-1Mo steel wire mesh was placed between the inner and outer tubes to decrease the flow resistance at the gap interface. Their leak gas flow characteristics, thermal performance, and mechanical properties were compared with those for the conventional mechanically bonded tube. The test results showed that the wire mesh filled DWT had very good leak detection characteristics compared with the mechanically bonded DWT. It has been confirmed that the wire mesh filled DWT has the potential to be used in double wall steam generators.
