| 摘要 |
A fastener locking device for attaching the lower end of a guide thimble to the upper adapter plate of a fuel assembly bottom nozzle includes a connecting fastener and an annular locking sleeve. The fastener has an elongated body portion and an enlarged head portion, and is insertable from the bottom through a passageway of the bottom nozzle. The fastener body portion is externally-threaded for forming a threaded connection with an internally-threaded plug on the lower end of the guide thimble. Also, the fastener head portion has a cross-sectional size larger than that of the fastener body portion and of a small diameter upper passageway portion but smaller than that of a large diameter lower passageway portion for defining an annular gap therebetween and bottoming against an annular ledge which divides the upper and lower passageway portions. The fastener head portion also has a annular outwardly-opening groove defined therein. The annular locking sleeve has opposite upper and lower end segments. The sleeve upper end segment is insertable into the annular gap, and has a smaller cross-sectional size than that of the fastener head portion and an annular inwardly-extending lip thereon which fits into the annular groove when the sleeve is inserted into the gap. Also, the sleeve upper end segment contains a plurality of circumferentially spaced axially-extending slots which facilitates resilient circumferential expansion of the cross-sectional size thereof for fitting it snugly about and past the fastener head portion and into frictional engagement with a knurled exterior surface on the fastener head portion and for fitting the lip on the sleeve past the fastener head portion and into the groove. The other sleeve end segment has projections which mate with recesses defined in the lower passageway portion when the sleeve is inserted into the gap.
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