Bolt fixing device of jet pump beam

摘要

A jet pump (18) is provided with a riser (20) as a coolant supply tube, an inlet mixer (22) forming a turn-around path for the coolant, a diffuser (23) and a jet pump beam (27) provided with a bolt fixing device (35). The bolt fixing device (35) includes: a head bolt (30) of a jet pump beam (27) for pushing and supporting the inlet mixer (22) from an upper side of the riser (20), the head bolt (30) being provided with a polygonal head portion (32); a lock cap (36) provided on the polygonal head portion (32) of the head bolt (30) to be slidable in an axial direction thereof and integrally rotatable; a body housing (37) disposed on an upper surface of the jet pump beam (27) and adapted to accommodate the lock cap (36); a plurality of tapered external teeth (44) formed on an outer peripheral side surface of the lock cap (36); and a plurality of internal tooth-shaped grooves (45) formed to the body housing (37) so as to be selectively engaged with the external teeth (44) of the lock cap (36) so as to fix the head bolt (30) of the jet pump beam (27).