Patent ID: 6763570
Filing Date: 2004-07-20
Classification: B23P,F16B,G21C,Y02E,Y10T

Abstract:
A method of closing a pressure vessel, comprising the steps of:placing a closure head having a flange over and spaced from a flange of a pressure vessel body containing a plurality of radioactive fuel assemblies; installing closure studs in closure stud holes of the pressure vessel body flange; attaching hydraulic nut assemblies to the closure studs; connecting hydraulic hoses between the hydraulic nut assemblies and a pressure source; simultaneously pressurizing the hydraulic nut assemblies from the pressure source to simultaneously apply a force to the closure studs sufficient to seat the spaced apart closure head flange on the pressure vessel body flange and to elongate the closure studs; locking the hydraulic nut assemblies in place over the closure head flange while the force is applied to the closure studs and the closure studs are elongated; releasing the hydraulic pressure on the hydraulic nut assemblies while the hydraulic nut assemblies are locked in place over the closure head flange and the closure studs are elongated; and then returning the pressure vessel to on-line operations with the hydraulic nut assemblies attached to the closure studs and with the closure head flange extending outwardly of the hydraulic nut assemblies.