STRUCTURAL DESIGN FOR AN INTERMEDIATE HEA T-EXCHANGER OF THE HTTR

The Intermediate Heat Exchanger (IHX) of the High Temperature Engineer ing Test Reactor (HTTR) is a helium-helium type heat exchanger with th e heat capacity of 10 MW. The internal structures such as heat transfe r tubes made of Hastelloy XR are used normally at about 930 degrees C because the IHX can supply the secondary helium gas with the maximum t emperature of 905 degrees C transferred from the primary helium gas of 950 degrees C. They compose the primary boundary and their creep stra in and creep damage evaluated conservatively based on the elastic anal ysis cannot meet the required criteria with enough margin. The design method based on the complete creep analysis was used for the primary c oolant boundary components. This report describes an evaluation proced ure based on the creep analysis and its results. The results show that the creep strain and creep damage increased rapidly during a few init ial cycles, however, increased far less after that. The results can me et the design limit for 10(5)h of the HTTR life time.