Steam generator nozzle dam

Abstract

A nozzle dam assembly for closing off a nozzle of a steam generator and a process for remotely positioning such nozzle dam are disclosed. The nozzle dam includes a mounting ring mounted on an inner surface of the steam generator about a periphery of an inner opening of the nozzle, at least one substantially planar central section and two substantially planar side sections together forming a substantially planar surface, the surface being of a greater diameter than the inner opening of the nozzle. Securing devices are also provided for securing each of the sections to the mounting ring after all the sections are positioned over the inner opening of the nozzle. Also provided is a sealing gasket which is secured to the central section with the sealing gasket having a diameter substantially equal to a diameter of the substantially planar surface formed by the sections for forming a fluid tight seal between a periphery of the substantially planar surface and the inner surface of the steam generator about the periphery of the inner opening of the nozzle. Each of the sections are initially passed through the manway of the steam generator. Once inside the channel head of the nuclear steam generator, the central section of the nozzle dam is retrieved by a robotic arm and positioned over a central portion of the nozzle opening. The robotic arm then positions the remaining side sections over the opening. Once each of the sections are aligned and positioned on the mounting ring, a bolt torque mechanism is then attached to the robotic arm and integral hold down bolts of the sections are sequentially tightened.