Abstract: The similarity and difference of LBB and BP piping design were analyzed from the aspect of their design philosophy, as well as the material quality requirement, fabrication requirement, application scope, leak detection, crack analysis, local effect and global effect. The research results show that BP’s “defense in depth” system encompasses the main content of LBB. Requirements of BP pipe are more complicated than that of LBB. Local effect and global effect of primary coolant pipes between application of LBB concept and that of BP concept are almost the same.