Interface reaction between fuel and cladding after Pb bonding

Full text follows: Blanket fuel assembly contains a bundle of 331 pins arrayed in triangular pitch which has hexagonal bundle structure. Either alloy type TRU-Zr fuel or dispersion type (TRU-10wt.%Zr)-Zr fuel is considered as a blanket fuel for HYPER(Hybrid Powder Extraction Reactor). In case of dispersion type fuel, the particles of TRU-10wt.%Zr alloy are dispersed in Zr matrix. Blanket rod is made of sealed tubing containing fertile material in columns. In alloy type TRU-Zr fuel, the blanket fuel slug is immersed in lead for thermal bonding with the cladding. The blanket fuel cladding material is ferritic-martensitic steel HT9. In this study, interface reaction between fuel and cladding after Pb bonding will be investigated systematically. U-55wt%Zr alloy fuel was fabricated instead of the actual TRU-Zr fuel and HT9 is used for the cladding material. In order to clarify reaction and diffusion characteristics of Pb bonding between fuel and cladding, a series of experiment has been executed with fuel and cladding in Pb melt at 650 C for 200, 500, 1000 hrs. After Pb bonding at 1000 hrs, diffusion reaction experiment is executed with fuel-cladding materials couples at 650, 700, 750 C for 100 hrs. The composition of diffusion layers and reaction products, and the diffusion depth were analyzed by using SEM/EDS. (authors)