Dashpot construction for a nuclear reactor rod guide thimble

摘要

A dashpot in a control rod guide thimble for a nuclear fuel assembly includes a lower tubular portion of an elongated main tube of the guide thimble, an auxiliary hollow tube inserted in the lower portion of the main tube, and an end plug attached to a lower end portion of the auxiliary tube. The auxiliary tube has an outside diameter slightly less than an inside diameter of the main tube to permit a close fitting relationship between an exterior surface of the auxiliary tube and an interior surface of the main tube lower portion. The auxiliary tube also has an upper end portion with an inside surface portion in axial cross-section flaring upwardly and outwardly to provide a tapered transition extending between and connecting an interior surface of the auxiliary tube with the exterior surface thereof.