METHOD OF CLOSING A PRESSURE VESSEL

摘要

A pressure vessel having a removable closure head in a high radiation environment is closed by placing the closure head having a flange over and spaced from the flange of a pressure vessel body containing fissile material. The closure studs are installed in closure stud holes of the pressure vessel body flange. Transition nut members of hydraulic nut assemblies are threaded onto the closure studs. Hydraulic hoses are connected between the hydraulic nut assemblies and a pressure source. The pressure source simultaneously pressurizes the hydraulic nut assemblies to simultaneously apply a uniform 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. The hydraulic nut assemblies are locked in place over the closure head flange while the force is applied to the closure studs and the closure studs are elongated. The hydraulic pressure on the hydraulic nut assemblies is released while the hydraulic nut assemblies are locked in place over the closure head flange and the closure studs are elongated. The hydraulic nut assemblies may remain connected with the hydraulic hoses after the pressure vessel has been returned to on-line operations and is generating thermal power. The hydraulic hoses connected with the hydraulic nut assemblies may be vented while generating thermal power in the pressure vessel.