Nuclear fuel assembly bottom nozzle attachment system allowing reconstitution

摘要

A nuclear reactor fuel assembly bottom nozzle to guide thimble attachment system and method allowing bottom nozzle removal and replacement without inverting the fuel assembly. At manufacture, a bottom-insertable, two-headed bolt secures the bottom nozzle adaptor plate to the guide thimble bottom end plug. The two-headed bolt is unthreadable in the guide thimble from the top of the upright fuel assembly. At reconstitution, a top-insertable bolt fastener secures the replacement or original bottom nozzle adaptor plate to the guide thimble bottom end plug. The bolt fastener is inserted in the guide thimble from the top of the upright fuel assembly. The bolt fastener is unthreadable in the guide thimble from the top of the upright fuel assembly for a second reconstitution. Less preferably, the bolt fastener also can be used for original manufacture (in place of the two-headed bolts previously discussed).