Double lock joint for attaching top nozzle to guide thimbles of nuclear fuel assembly.

摘要

The invention relates in particular to a double lock joint structure for attaching and releasably locking the adapter plate of the top nozzle of a fuel assembly to an upper end portion of a guide thimble which is inserted in a passageway through the adapter plate and is elastically compressible to permit withdrawal therefrom. The guide-thimble upper end portion (36) extends through the passageway (36) and above the adapter plate (34), and it has thereon upper and lower retaining means (bulges 50, 52) located directly above and below, respectively, the adapter plate to capture it therebetween. The double lock joint structure includes also a locking tube (58) removably inserted in the guide thimble end portion (38) and having upper and lower protrusions (60, 62) which form interference fits with the retaining means on guide thimble end portion.