Method of repairing a nuclear assembly

Abstract

A method of repairing a nuclear power facility metal component assembly with a "Class A" fastening between hard metal parts (12,14) includes several steps they are: providing aligned openings (20,22) in a plurality of hard metal parts (12,14) to be assembled; EDM machining a non-cylindrically shaped cavity (16) which is analogous to a counterbore having a cavity opening (24) smaller than the cavity base (18); inserting a locking collar (10) with a central aperture (32) and surrounding flange (3) to receive a bolt head (42) and with weakened zones of deformation (34) through the cavity opening (24); inserting a headed and threaded bolt (40) through the central aperture (32) of the locking collar (10) and into the aligned bores (20,22); providing threads (46a) in another of the hard metal parts to mate the bolt threads (46); torquing the bolt (40) in the provided mating threads (46a) to draw the bolt head (42) toward the cavity base (18) and deforming the locking collar at its weakened zones of deformation (34) to cause it to expand to an overall dimension which prevents its passage out of the cavity opening (24); and, deforming the flange (30) to interfere with rotation of the bolt by engaging depressions (50) in the bolt head (42).

Dependencies are inferred from the claim text.