Abstract: In a nuclear fuel assembly having a coolant conducting or water tube which also retains the spacers in axial position, the fuel rods experience greater axial growth with exposure than the water tube creating a risk that the water tube might become disengaged from the supporting tie plates. An arrangement for preventing such disengagement is described including lengthened end plug shanks for the water tube, a protective boss surrounding the lower end plug shank to protect it from flow induced vibration, a conical seat for the lower end plug and an arrangement for limiting upward movement of the water tube.

Abstract: A fuel assembly for a nuclear reactor including a plurality of fuel rods held in spaced, parallel position between upper and lower tie plates and retained in lateral position by intermediate spacers and having a water tube in lieu of a fuel element in one or more of the rod positions, the water tubes having an outside diameter greater than that of the fuel rods and the spacer springs in the spacer cells of the water tubes being modified to accommodate the larger diameter of the water tubes.