a technique is provided for engaging and disengaging burnable poison rods from the spider in a fuel assembly . the cap on the end of each of the burnable poison rods is provided with a shank that is received in the respective bore formed in the spider . in one illustrative embodiment , the shank is deformed to firmly secure the rod and attached shank in the spider bore . pressing the shank in the direction of the bore axis overcomes the deformation to release the particular rod from the spider .