| 摘要 |
<p>Known nuclear fuel assemblies having vertically extending fuel elements and guide tubes that extend through spacer grid assemblies. Each assembly has intersecting slotted grid plates forming a plurality of cells through which the guide tubes extend. In this invention, each guide tube is formed integrally with a plurality of spaced protuberancies such that each tube has a cross-section at each protuberancy greater than the distance between the plates forming the cell, the protuberancies being longitudinally aligned with and spaced relative to the plates to engage the plates and restrain longitudinal movement of the spacer grid assembly relative to the guide tube beyond the longitudinal spacing and to permit the guide tube including the protuberancies to be inserted through a cell. The use of integrally-formed protuberancies has the advantage of avoiding the addition of material to the fuel assembly which is capable of parasitically absorbing neutrons.</p> |
