Nuclear reactor coolant pump impeller/shaft assembly

A pump is described comprising: (a) a casing having an inlet and an outlet in fluid communication for circulating fluid coolant through the pump; (b) a shaft positioned in the casing; (c) an impeller nut connected to the shaft; (d) a lockbolt fixedly connecting the impeller nut relative to the shaft; (e) passageway means with first and second ends for directing fluid from the lockbolt to the shaft; (f) first conduit means formed in the impeller nut in fluid communication with the first end of the passageway means and the inlet of the casing; and (g) second conduit means formed in the impeller nut in fluid communication with the second end of the passageway means and the outlet of the casing. A portion of the fluid coolant circulating through the inlet of the casing is pumped through the first conduit means, through the passageway means, out the second conduit means and into the outlet of the casing